Pozosta ELECRAFT-K2 User Manual

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BAND

RCL

BAND

STORE

EDIT

DISPLAY

RF/ALC

ANT 1/2

TUNE

LEVEL

E L E C R A F T

5 9 +20 40

RF 3 5 7 10

KEYER

AF GAIN

ALC

POWER

RF GAIN

K 2

NB ANT2 PRE ATT A B RIT XIT

T R A N S C E I V E R

RATE

LOCK

MODE

VOX

PRE/ATT

SPOT

RIT XIT

PF1

-1

A=BA/B

456

AGC

PF2

SPLITREV

XFIL

AFILCW RV

MSG

REC

OFF

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E L E C R A F T

K 2

160-10 Meter

S S B/CW

T r a n s c e i v e r

Owner’s Manual

Revision E, February 16, 2003

Elecraft • www.elecraft.com P.O. Box 69 • Aptos, CA 95001-0069 (831) 662-8345 • Fax: (831) 662-0830

 2003 Elecraft, LLC

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2 ELECRAFT

Table of Contents

1. INTRODUCTION.................................................................................................................................................................................... 3

2. SPECIFICATIONS ................................................................................................................................................................................ 5

3. PREPARATION FOR ASSEMBLY.................................................................................................................................................... 7

4. CONTROL BOARD............................................................................................................................................................................ 13

5. FRONT PANEL BOARD.................................................................................................................................................................... 21

6. RF BOARD.......................................................................................................................................................................................... 32

7. FINAL ASSEMBLY............................................................................................................................................................................. 75

8. OPERATION........................................................................................................................................................................................ 78

9. CIRCUIT DETAILS ............................................................................................................................................................................ 1

10. OPTIONS............................................................................................................................................................................................ 110

PARTS LIST.............................................................................................................................................................................APPENDIX A

SCHEMATIC .............................................................................................................................................................................APPENDIX B

BLOCK DIAGRAM..................................................................................................................................................................APPENDIX C

PHOTOGRAPHS.....................................................................................................................................................................APPENDIX D

TROUBLESHOOTING............................................................................................................................................................APPENDIX E

PARTS PLACEMENT DRAWINGS....................................................................................................................................... APPENDIX F

100-WATT STAGE AND RS232 I/O (K2/100) .......................................................APPENDIX G (SUPPLIED WITH KPA100 OPTION)

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ELECRAFT 3

1. Introduction

The Elecraft K2 is a high-performance, synthesized, CW/SSB transceiver that covers all HF bands. It is a true dual-purpose transceiver, combining the operating features you’d expect in a home-station rig with the small size and weight of a rugged, go-anywhere portable.

The basic K2 operates on 80-10 meter CW, and provides over 10 watts of RF output. If you prefer a full-power station, you can complete your K2 as a K2/100 at any time by adding the internal 100-watt final stage (KPA100 option). Assembly of the KPA100 is covered in Appendix G, a separate manual supplied with the KPA100 kit.

You can customize your K2 by choosing from a wide range of additional options:

 SSB adapter with optimized 7-pole crystal filter  Automatic antenna tuner (20 W internal or 150 W external)  160-m adapter with receive antenna switch  60-m adapter with low-level transverter interface  Computer control interface (RS232)  Noise blanker  Low-noise audio filter and real-time clock  Internal 2.9-Ah rechargeable battery

For a complete description of available options, see page 110. In addition to the options, a companion enclosure the same size and style as the K2 is available for those who wish to build their own matching station accessories (model EC2).

The K2 is an intermediate-level kit, yet you’ll be pleasantly surprised at how uncomplicated it is to build. All of the RF (radio-frequency) circuitry is contained on a single board, while two plug-in modules provide front panel and control functions. Wiring is minimal, unlike traditional kits which depend on complex wiring harnesses.

A unique feature of the K2 is that it provides its own built-in test equipment, including a digital voltmeter, ammeter, wattmeter, complete RF probe, and frequency counter. These circuits are completed early in assembly, so they're ready to be used when you begin construction and alignment of the RF board. We also provide complete troubleshooting and signal-tracing information.

In addition to this owner’s manual, you’ll find extensive support for the K2 on our website, www.elecraft.com. Among the available

materials are manual updates, application notes, photographs, and information on new products. There’s also an e-mail forum; sign-up is available from the web page. It’s a great way to seek advice from the K2’s designers and your fellow builders, or to tell us about your first QSO using the K2.

We’d like to thank you for choosing the K2 transceiver, and hope it meets your expectations for operation both at home and in the field.

Wayne Burdick, N6KR Eric Swartz, WA6HHQ

Pre-Wound Toroids Available

You can obtain a set of pre-wound toroids for the K2 if you prefer not to wind them yourself. Refer to our web site for details.

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4 ELECRAFT

Customer Service Information

Technical Assistance

If you have difficulty with kit construction, operation, or troubleshooting, we’re here to help. You may be able to save time by first consulting our web site, www.elecraft.com, or by posting

your question on our e-mail forum, elecraft@mailman.qth.net.

Telephone assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays) at 831-662-8345. Via e-mail, use

support@elecraft.com for support and parts@elecraft.com

request replacement parts. Please use e-mail when possible; this

gives us a written record of the details of your problem.

Repair Service

If necessary, you may return your completed kit to us for repair. Contact Elecraft before mailing your kit to obtain current information on repair fees. (Kits that have been soldered using acid core solder, water-soluble flux solder, or other corrosive or conductive fluxes or solvents cannot be accepted for repair.)

The following information should be provided to expedite repair: your name, address, and phone number; your e-mail address (if applicable); and a complete description of the problem.

Shipping: First, seal the unit in a plastic bag to protect the finish from dust and abrasion. Use a sturdy packing carton with 3" or more of foam or shredded paper on all sides. Seal the package with reinforced tape. (Neither Elecraft nor the carrier will accept liability for damage due to improper packaging.) Cover the "to" address label with clear tape so it will be weatherproof. Finally, call or send e-mail to obtain the proper shipping address.

Elecraft’s 1-Year Limited Warranty

This warranty is effective as of the date of first consumer purchase. Before requesting warranty service, you should complete the assembly, carefully following all instructions in the manual.

What is covered: During the first year after date of purchase, Elecraft will replace defective parts free of charge (post-paid). We will also correct any malfunction caused by defective parts and materials. You must send the unit at your expense to Elecraft, but we will pay return shipping.

What is not covered: This warranty does not cover correction of assembly errors or misalignment; repair of damage caused by misuse, negligence, or builder modifications; or any performance malfunctions involving non-Elecraft accessory equipment. The use of

acid-core solder, water-soluble flux solder, or any corrosive or conductive flux or solvent will void this warranty in its entirety. Also

not covered is reimbursement for loss of use, inconvenience, customer assembly or alignment time, or cost of unauthorized service.

Limitation of incidental or consequential damages: This warranty does not extend to non-Elecraft equipment or components used in conjunction with our products. Any such repair or

replacement is the responsibility of the customer. Elecraft will not be liable for any special, indirect, incidental or consequential damages, including but not limited to any loss of business or profits.

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ELECRAFT 5

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2. Specifications

All measurements were made using a 14.0 V supply and 50-ohm load unless otherwise indicated. Values are typical; your results will be somewhat different. Specifications are subject to change without notice. (See option manuals for additional specifications.)

General

Frequency ranges,2 MHz

Basic kit 3.5-4.0, 7.0-7.3,

10.0-10.2, 14.0-14.5, 18.0-18.2,

21.0-21.6, 24.8-25.0, 28.0-28.8 160 m (opt.) 1.8-2.0 60 m (opt.) 5.0-5.5

Size

Cabinet 3.0" H x 7.9" W x 8.3" D

(7.5 x 20 x 21 cm)

Overall 3.4" H x 7.9" W x 9.9" D

(8.5 x 20 x 25 cm)

Weight 3.3 lbs. (1.5 kg), excluding options

Supply voltage 9 to 15 VDC;

reverse-polarity protection; internal self-resetting fuse

Current drain,

Receive 120-150 mA in minimum-current

configuration; 180-250 mA typical

Transmit

Frequency control PLL synthesizer w/single VCO

Current varies with band, supply voltage, configuration, and load

impedance. We recommend a minimum 3.5-amp power supply.

2.0 A typical at 10 watts; programmable current limiting

covering 6.7-24 MHz in 10 bands; fine steps via DAC-tuned reference

VFO

Stability < 100 Hz total drift typ. from

cold start at 25° C

Accuracy

Resolution 10 Hz

Tuning steps 10 Hz, 50 Hz, and 1000 Hz nominal

Memories 20 (10 assigned to 160-10 m

RIT/XIT range +/- 0.6 to +/- 4.8 kHz (selectable);

The K2 can receive well outside the indicated bands, but this extended range is not specified or guaranteed Transmit ranges may be limited for export to some countries. The K2/100 (KPA100 option) limits transmit from 25-27.999 MHz to 10 watts or less.

See Frequency Calibration Techniques (page ).

+/- 30 Hz over a 500 kHz range (typ) when calibrated

(other step sizes available via menu)

Bands; 10 general-purpose)

10-40 Hz steps depending on range. Fine RIT mode steps 2-3 Hz typ.

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Transmitter

Power output range <0.5 W to >10 W (typ.);

Min. supply voltage 9.0 V min for 2 watts out recommended

Duty cycle 5 W, 100%; 10 W, 50%

Spurious products -40 dB or better @ 10 W (-50 typ)

Harmonic content -45 dB or better @ 10 W (-55 typ)

Load tolerance 2:1 or better SWR recommended;

T-R delay approx. 10 ms-2.5 sec, adjustable

External keying 70 WPM max.

Receiver

Preamp On Preamp Off

Sensitivity (MDS) -135 dBm -130 dBm

power setting resolution 0.1 W, accuracy 10% @ 5 W

9.5 V min for 5 watts out

10.0 V min for 7 watts out

-order intercept 0 to +7.5

-order intercept +70 +70

Dynamic range,

Blocking 125 dB 133 dB Two-tone 96 97

10.5 V min for 10 watts out I.F. 4.915 MHz (single conversion)

Selectivity,

CW 7-pole variable-bandwidth crystal

filter, approx. 200-2000 Hz 7-pole fixed-bandwidth crystal

SSB

filter, 2.2 kHz typ.

will survive operation

Audio output 1 watt max. into 4-ohm load

into high SWR

Speaker internal: 4 ohm, 3 W;

Rear-panel jack for external speaker

Headphones 4 - 32 ohms, stereo or mono

+10

CW sidetone 400-800 Hz in 10 Hz steps

Keyer

Keying modes Iambic A and B; adjustable weight

Speed range 9 - 50 WPM

Message memory 9 buffers of 250 bytes each; 1-level

For reference only; not guaranteed. If higher power than shown here is to be

used for a given supply voltage, monitor transmitter output signal.

chaining; auto-repeat (0 - 255 s)

Varies with band.

With optional SSB adapter. Other CW and SSB fixed crystal filter options

may be available

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ELECRAFT 7

3. Preparation for Assembly

Overview of the Kit

The K2 uses modular construction, both physically and electrically. This concept extends to the chassis (Figure 3-1). Any chassis element can be removed during assembly or troubleshooting. (Also see photos in Appendix D.) If the KPA100 is installed, it takes the place of the original top cover.

Side

Panel

Top Cover

Heat

Sink

Front Panel

Bottom

Cover

(Right side panel

not shown)

As shown in Figure 3-2, there are three printed circuit boards (PCBs) in the basic K2 kit: the Front Panel board, Control Board, and RF board. Option modules plug into the RF or Control board, but are not shown here.

Control

Front Panel

Figure 3-2

Figure 3-1

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8 ELECRAFT

Board-to-board Connectors

The circuit boards in the K2 are interconnected using board-to-board connectors, which eliminates nearly all hand wiring. Gold-plated contacts are used on these connectors for reliability and corrosion resistance.

Figure 3-3 shows a side view of the PC boards and board-to-board connectors. As can be seen in the drawing, the Front Panel board has a connector J1 which mates with right-angle connector P1 on the RF board. Similarly, right-angle connector P1 on the Control Board mates with J6 on the RF board. (Not shown in this drawing are two additional right-angle connectors on the Control board, P2 and P3, which mate with J7 and J8 on the RF board.)

These multi-pin connectors are very difficult to remove once soldered in place. Refer to Figure 3-3 during assembly to make sure you have each connector placed correctly before soldering.

ront Panel

Control Board

F Board

Figure 3-3

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ELECRAFT 9

There are six steps in the K2 assembly process:

1. Control Board assembly

2. Front Panel Board assembly

3. RF Board assembly and test, part I (control circuits)

4. RF Board assembly and test, part II (receiver and synthesizer)

5. RF Board assembly and test, part III (transmitter)

6. Final assembly

This assembly sequence is important because later steps build on the previous ones. For example, in step 3 you’ll put the modules together for the first time, allowing you to try out the K2’s built-in frequency counter. The counter will then be used in step 4 to align and test the receiver and synthesizer on 40 meters. In step 5 all the pieces will come together when you complete the transmitter and filters, then align the K2 on all bands. The last few details—speaker, tilt stand, etc.—will be wrapped up in step 6.

Unpacking and Inventory

When you open the kit you should find the following items:

 six chassis pieces (Figure 3-1)  three printed circuit boards (Figure 3-2)  FRONT PANEL board components bag  CONTROL board components bag  RF board components in two bags  MISCELLANEOUS components bag (includes hardware)  WIRE bag  4-ohm Speaker, 5 small knobs, and large tuning knob  plastic tube containing the latching relays  an envelope containing the LCD bezel, green LED bargraph

filter, serial number label, thermal insulators, and other items

Inventory

We strongly recommend that you do an inventory of parts before beginning to assemble the kit. It is not necessary to inventory the resistors, which are supplied attached to tape in assembly order.

Even if you don’t do an inventory, it is helpful to familiarize yourself with the parts list, Appendix A. Additional information on identifying capacitor, chokes, and resistors is provided below.

Identifying Capacitors

Small-value fixed capacitors are usually marked with one, two, or three digits and no decimal point. If one or two digits are used, that is always the value in picofarads (pF). If there are three digits, the third digit is a multiplier. For example, a capacitor marked "151" would be 150 pF (15 with a multiplier of 10 would be 33 pF, and "102" would be 1000 pF (or .001 µF). In rare

cases a capacitor manufacturer may use "0" as a decimal placeholder. For example, "820" might mean 820 pF rather than

the usual 82 pF. Such exceptions are usually covered in the parts lists. To be safe, measure the values of all capacitors below 1000 pF (most DMMs include capacitance measurement capability).

Fixed capacitors with values of 1000 pF or higher generally use a decimal point in the value, such as .001 or .02. This is the value in microfarads (µF). Capacitors also may have a suffix after the value, such as ".001J." In some cases the suffixes or other supplemental markings may be useful in identifying capacitors.

Hard-to-identify capacitor values:

3.3 pF: These capacitors may have pillow-shaped, dark-green

bodies about 1/8" (3 mm) square, with a black mark on the top. The "3.3" label may be difficult to read without a magnifying glass.

). Similarly, "330"

150 pF: These are correctly marked "151" on one side, but the other side may be marked #21 ASD, where "#21" looks like "821."

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Resistors, Chokes, and the Color Code

All resistor and RF choke color bands are provided in the text along with their values. However, it is helpful to familiarize yourself with the color code to allow you to identify these components without having to refer to the text or parts list each time.

The color-code chart, Figure 3-4, shows how to read the four color bands on 5% resistors. 1% resistors are similar, except that they use five bands (three significant digits, multiplier, and tolerance). For example, a 1,500 ohm (1.5 k) 5% resistor has color bands BROWN, GREEN, and RED. A 1.5 k, 1% resistor has color bands BROWN, GREEN, BLACK, BROWN. The multiplier value is 1 rather than 2 in the 1% case because of the third significant digit.

Because 1% resistors have color bands that are sometimes hard to distinguish clearly, you should always check their resistance using an ohmmeter.

The markings on RF chokes reflect their value in microhenries (µH). Like 5% resistors, chokes use two significant digits and a multiplier. Example: an RF choke with color bands RED, VIOLET, BLACK would have a value of 27 µH.

Tools

The following specialized tools are supplied with the K2:

 .050" (1.3 mm) Allen Wrench, short handle  5/64" (2 mm) Allen Wrench, long handle  Double-ended plastic inductor alignment tool

Color Code

Tolerance (gold = 5%, silver = 10%)

Multiplier

Second Digit

First Digit

Color MultiplierDigit

Black 0 x 1 Brown 1 x 10 Red 2 Orange x 1K

Yellow 4 x 10K Green 5 x 100K Blue 6 x 1M Violet 7 Gray 8 White 9

Silver -- x .01 Gold -- x 0.1

Figure 3-4

x 100

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ELECRAFT 11

In addition to the tools supplied, you will need these standard tools:

 Fine-tip soldering iron, 20-40 watt (temperature-controlled

preferred, with 700 or 800°F tip [370-430°C]

 IC-grade, small-diameter (.031") solder (DO NOT use acid-

core solder, water-soluble flux solder, additional flux, or solvents of any kind, which will void your warranty)

 Desoldering tools (wick, solder-sucker, etc.)  Needle-nose pliers  Small-point diagonal cutters, preferably flush-cutting  Small Phillips screwdriver  Jeweler’s flat-blade screwdriver

While not required, the following items are recommended:

 DMM (digital multimeter) for doing resistance and voltage

checks. A DMM with capacitance measurement capability is strongly recommended (see Identifying Capacitors).

 Magnifying glass  Conductive wrist strap

Assembly Notes

This symbol is used to alert you to important information

about assembly, alignment, or operation of the K2.

In some steps you will actually be installing multiple components of a particular type. In this case the instructions will be followed by a table listing all of the components to be installed, so you won’t need to refer to the parts list during assembly. The order that the components are installed corresponds to their PCB locations.

Do not skip any assembly steps; you may find that you’ve installed one component that hinders the installation of another.

Forming component leads: In a few cases you’ll find that the

space provided for a component on the PC board is larger than the distance between the leads on the part itself. In such cases, you’ll need to carefully bend the leads out and then down to fit the given space. Always use needle-nose pliers to accomplish this task, and bend the leads–don’t tug on them. This is especially important with capacitor leads, which are fragile.

Bottom-Mounted Components

A number of components in the K2 are mounted on the bottom of the PC boards to improve component spacing or for electrical reasons. Component outline symbols are provided on both sides of each board, so it will always be clear which side a particular component goes on. You’ll be able to tell the top of the board from the bottom easily: the top side has far more parts. Bottommounted parts are identified on the schematic by this symbol:

Photographs

You should review the photographs in Appendix D to get an idea of what the completed PC board assemblies look like.

Step-by-Step Assembly

Each step in the assembly process is accompanied by a check-box:

Top/bottom interference: In a few cases, top-mounted parts may interfere with the trimming and soldering of a bottom-mounted part. In this case, pre-trim the leads of the bottom-mounted part before final placement, and solder it on the bottom rather than on the top. (Since all holes are plated-through, you can solder on either side.)

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12 ELECRAFT

Integrated Circuits and ESD

The K2 transceiver uses integrated circuits and transistors that can be damaged by electrostatic discharge (ESD). Problems caused by ESD can often be difficult to troubleshoot because components may only be degraded, at first, rather than fail completely.

To avoid such problems, simply touch an unpainted, grounded metal surface before handling any components, and occasionally as you build. We also recommend that you take the following antistatic precautions (in order of importance):

 Leave ESD-sensitive parts in their anti-static packaging until

you install them

 Ground yourself using a wrist strap with a series 1 megohm

resistor (do NOT ground yourself directly, as this poses a shock hazard)

 Make sure your soldering iron has a grounded tip  Use an anti-static mat on your work bench

IC Sockets

Sockets are used for only the largest ICs. You should not use sockets for the other ICs because they tend to be unreliable and can cause problems due to added lead length. Since sockets are not used in most cases, you must double-check the part number and orientation of each IC before soldering.

Soldering, Desoldering, and Plated-Through Holes

CAUTION: Solder contains lead, and its residue can be toxic. Always wash your hands after handling solder.

The printed circuit boards used in the K2 have circuitry on both sides ("double-sided"). Boards of this type require plated-through holes to complete electrical connections between the two sides.

When you solder components on these boards, the solder fills the plated holes, making excellent contact. This means that you do not need to leave a large "fillet" or build-up of solder on top of the pads themselves. A small amount of solder will do for all connections.

Unfortunately, removing components from double-sided PC boards can be difficult, since you must get all of the solder back out of the hole before a lead can be removed. To do this, you'll need solder wick and a vacuum desoldering tool (see techniques below).

The best strategy for avoiding de-soldering is to place all components properly the first time. Double-check values and orientations, and avoid damaging parts via ESD.

When removing components:

 Don't pull a lead or pin out of a hole unless the solder has been

removed, or you are applying heat. Otherwise, you can literally pull out the plating on the plated-through hole.

 Limit soldering iron contact to a few seconds at a time.  Use small-size solder-wick, about 0.1" or 2.5 mm wide. Use the

wick on both the top and bottom pads when possible. This helps get all of the solder out of the hole.

 Buy and learn how to use a large hand-operated vacuum

desoldering tool, such as the "Soldapullt," model DS017LS. Small solder suckers are not effective.

 With ICs and connectors, clip all of the pins at the body first,

then remove all of the pins slowly, one at a time. You may damage pads and traces by trying to remove a component intact, possibly leaving a PC board very difficult to repair.

 Invest in a PC board vice with a heavy base if possible. This

makes parts removal easier because it frees up both hands.

 If in doubt about a particular repair, ask for advice from

Elecraft or from a someone else with PCB repair experience. Our e-mail reflector is also an excellent source for help.

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ELECRAFT 13

4. Control Board

The Control board is the "brain" of the K2. It monitors all signals during receive and transmit, and handles display and control functions via the Front Panel board. The microcontroller, analog and digital control circuits, automatic gain control (AGC), and audio amplifier are located on this board.

Components

Review the precautions described in the previous section before handling any IC’s or transistors. These components can be damaged by static discharge, and the resulting problems are often difficult to troubleshoot.

There are five sizes of 4-40 machine screws provided with the kit. The relative sizes of the screws are shown below for identification purposes (not to scale). All of the screws are black anodized except for the 7/16" (11 mm) screws. The 3/16" (4.8 mm) pan-head screws are the most numerous, and will be referred to as chassis screws throughout the manual. There is only one flathead, 3/16" screw.

Flat-head, 3/16” (4.8 mm)

Open the bag of components labeled CONTROL and sort the parts into groups (resistors, diodes, capacitors, etc.). If any of the components are unfamiliar, identify them using the illustrations in the parts list, Appendix A.

Locate the Control board. It is the smallest of the three K2 PC boards, labeled "K2 CONTROL" on the front side, in the lower right-hand corner. The lower left-hand corner is notched.

Open the bag labeled MISCELLANEOUS and empty the contents into a shallow box or pan. This will prevent loss of any of the small hardware while allowing you to locate items as needed.

The Allen wrenches are located in a small bag with the MISCELLANEOUS items. These wrenches may have been oiled during manufacturing. Remove the wrenches and wipe off the oil, if any, then discard the bag.

Pan-head, 3/16” (4.8 mm)

(chassis screws)

Pan-head, 3/8” (9.5 mm)

Pan-head, 7/16” (11 mm)

Pan-head, 1/2” (12.7 mm)

Identify all of the 4-40 screws and sort them into groups.

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14 ELECRAFT

Assembly

The side of the Control board with most of the components is the top side. With the top side of the Control board facing you and the notch at the lower left, locate the position of resistor R5, near the left edge. The label "R5" appears just below the resistor’s outline.

Install a 33-k resistor (orange-orange-orange) at R5, with the orange bands at the top and the gold band (indicating 5% tolerance) at the bottom. Make sure it is seated flush with the board, then bend the leads on the bottom to hold it in place. Do not solder this resistor until the remaining fixed resistors have been installed in the next step.

Install the remaining fixed resistors, which are listed below in left-to-right PC board order. The resistors should all be oriented with their first significant-digit band toward the left or top. This will make the color codes easier to read if you need to re-check the values after installation. Check 1% resistors with an ohmmeter.

Note: When multiple items appear on one line in a component list such as the one below, complete all items on one line before moving on to the next, as indicated by the small arrow. (In other words, install R5 first, then R2, then go to the second line.)

__ R5, 33 k (ORG-ORG-ORG) ⇒ __ R2, 3.3 M (ORG-ORG-GRN) __ R3, 10 k (BRN-BLK-ORG) __ R4, 5.6 k (GRN-BLU-RED) __ R6, 100 (BRN-BLK-BRN)

__ R7, 1.78 k, 1% (BRN-VIO-GRY-BRN) __ R8, 100, 1% (BRN-BLK-BLK-BLK) __ R9, 806 k, 1% (GRY-BLK-BLU-ORG) __ R10, 196 k, 1% (BRN-WHT-BLU-ORG)

__ R16, 10 (BRN-BLK-BLK) ⇒ __ R17, 3.3 M (ORG-ORG-GRN) __ R21, 10 k (BRN-BLK-ORG) __ R20, 2.7 ohms (RED-VIO-GLD)

Solder all of the resistors, then trim the leads as close as

possible to the solder joints. Some builders prefer to trim the

leads before soldering. Either method can be used.

Locate RP6, a 5.1 k, 10-pin resistor network. ("RP" means "resistor pack," another name for resistor networks.) RP6 is usually labeled "770103512." Check the parts list for alternative resistor network labels if necessary. Pin 1 of RP6 is indicated by a dot.

Locate the component outline for RP6 at the left end of the PC board. Install the resistor network so that the end with the dot is lined up with the "1" label.

Make sure the resistor network is seated firmly on the board, then bend the leads at the far ends in opposite directions to hold it in place. (Do not trim the leads.) Do not solder RP6 yet.

Components with many leads are difficult to remove once

soldered. Double-check the part numbers and orientation.

below. Do not solder them until the next step.

__ RP1, 3.9 k, 10 pins (770103392) __ RP7, 33 k, 8 pins (8A3.333G) __ RP2, 82 k, 8 pins (77083823) __ RP3, 47 k, 10 pins (10A3.473G) __ RP5, 470, 10 pins (10A3.471G) __ RP4, 82 k, 8 pins (77083823)

board. R1 will sit above the board due to the shoulders on its pins. Hold it in place (flat, not tilted) while soldering.

component outline. Make sure the L1 is pressed down onto the PC board as far as it can go, then bend the leads slightly to hold it in place while soldering.

Install the remaining resistor networks in the order listed

Solder all of the resistor networks.

Install potentiometer R1 (50 k), located at the left side of the

Install the 82 mH shielded inductor (L1) as shown by its

Page 16

ELECRAFT 15

Install the diodes listed below, beginning with D1, which is in the upper left-hand corner of the PC board. (Refer to the parts list if necessary to identify the different types of diodes.) If a diode has only one band, the end with the band (the cathode) should be oriented toward the banded end of the corresponding PC board outline. If a diode has multiple bands, the widest band indicates the cathode end.

__ D1, 1N4148 __ D2, 1N4148 __ D3, 1N5817

Double-check the orientation of the diodes, then solder.

Install the small fixed capacitors listed below, beginning with C2 in the upper left-hand corner of the board. (This list includes all of the fixed capacitors on the Control board except the tall, cylindrical electrolytic types, which will be installed later.) The list shows both the value and the capacitor labels, using notation explained in the previous section. After installing each capacitor, bend the leads outward to hold it in place, but do not solder.

Note: Remember to complete all items in each line before moving on to the next. (Install C2, C3, and C4, then C7, etc.)

__ C2, .001 (102) ⇒ __ C3, .01 (103) ⇒ __ C4, 0.47 (474) __ C7, 330 (331) __ C6, .047 (473) __ C8, 39 (39) __ C9, .01 (103) __ C10, .01 (103) __ C12, .0027 (272) __ C5, .01 (103) __ C14, .047 (473) __ C17, .01 (103) __ C42, 0.1 (104) __ C16, .047 (473) __ C11, .01 (103) __ C19, .047 (473) __ C21, 33 (33)

Install and solder the electrolytic capacitors listed below, which are polarized. Be sure that the (+) lead is installed in the hole marked with a "+" symbol. The (+) lead is usually longer than the (–) lead, and the (–) lead is identified by a black stripe (Figure 4-1).

Figure 4-1

__ C1, 2.2 µF ⇒ __ C13, 22 µF ⇒ __ C15, 100 µF __ C28, 220 µF __ C29, 220 µF __ C33, 2.2 µF __ C32, 22 µF

Install and solder ceramic trimmer capacitor C22. Orient the flat side of this trimmer as shown on its PC board outline.

Using a small flat-blade screwdriver, set C22 so that its

screwdriver slot is parallel to the outline of nearby crystal X2.

Locate Q12 (type PN2222A), which is a small, black TO-92 package transistor. Q12 and other TO-92 transistors may have either of the two shapes shown in Figure 4-2. The large flat side

of the device must be aligned with the flat side of the component outline. The part number may be found on either

side.

__ C23, .01 (103) __ C20, .001 (102) __ C18, .01 (103) __ C43, .001 (102) __ C27, .022 (223) __ C25, 0.1 (104) __ C26, 0.1 (104) __ C24, .0027 (272) __ C31, .047 (473) __ C34, .001 (102) __ C30, .047 (473) __ C40, .01 (103) __ C35, .01 (103) __ C36, .0027 (272) __ C39, .01 (103) __ C41, .01 (103) __ C37, .01 (103) __ C38, 680 (681)

Solder all of the small fixed capacitors.

Figure 4-2

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16 ELECRAFT

Install Q12 near the upper left-hand corner of the PC board. Align the large flat side of Q12 with its PC board outline as in Figure 4-2. The body of the transistor should be about 1/8" (3 mm) above the board; don’t force it down too far or you may break the leads. Bend the leads of the transistor outward slightly on the bottom to hold it in place. Solder Q12.

Install the remaining TO-92 package transistors in the order listed below.

__ Q11, PN2222A ⇒ __ Q1, 2N3906 ⇒ __ Q2, 2N3906 __ Q3, 2N7000 __ Q4, 2N7000 __ Q5, 2N7000 __ Q6, J310 __ Q7, J310 __ Q8, PN2222A __ Q9, MPS5179 __ Q10, MPS5179

Solder and trim the leads of these transistors.

Install crystals X1 and X2 so that they are flat against the board. X1 is 5.068 MHz and is located near the notch in the lower left-hand corner. X2 is 4.000 MHz, and is located near the center of the board.

Solder the crystals.

Prepare two 3/4" (19 mm) jumpers wires from discarded component leads. These short jumpers will be used to ground the crystal cans in the next step.

Figure 4-3

The voltage regulators, U4 and U5, will be installed in the

following steps. These regulators have different voltages and must not be interchanged. Check the labels before soldering.

Install U4 (LM2930T-8) and U5 (78M05, 7805T, L7805, etc.), forming the leads as indicated (Figure 4-4). Fold the pins over the shaft of a small screwdriver to create smooth bends. After inserting the leads into the proper holes, secure each IC with a 4-40 x 3/8" (9.5 mm) machine screw, #4 lock washer, and 4-40 nut. (These regulators may have either plastic or metal mounting tabs.)

Use smooth bend, not sharp

Grounding the crystal cans in the following step is required

to ensure proper crystal oscillator performance.

Referring to Figure 4-3, insert the jumper wires into the grounding holes provided near X1 and X2. Fold each wire over the top of the crystal and solder it to the top of the can. (Only a small amount of solder is required.) Then solder and trim the wire on the bottom of the board.

Figure 4-4

Solder the voltage regulator ICs.

Trim the IC leads as close to the PC board as possible.

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ELECRAFT 17

Install a 40-pin IC socket at U6. (The microcontroller will be inserted into the socket in a later step.) Orient the notched end of the socket to the left as shown on the PC board outline. Bend two of the socket’s diagonal corner leads slightly to hold the socket in place, then solder only these two pins. If the socket does not appear to be seated flat on the PC board, reheat the solder joints one at a time while pressing on the socket.

Solder the remaining pins of the 40-pin socket.

The connectors used in the following steps have plastic

bodies that can may melt if too much heat is applied during soldering, causing the pins to be mis-positioned. Limit soldering time for each pin to 3 seconds maximum (1 to 2 seconds should be adequate).

Figure 4-5, the polarizing tab on each connector should be closest to the top edge of the board. P5, the voltmeter input connector, can be found near the upper left-hand corner of the board. P6 is used for frequency counter input, which is in the upper right-hand corner.

Install the 2-pin male connectors, P5 and P6. As shown in

Locking

Tab

op side of

C Board

Install the 10-pin, dual-row connector, P4. It is located to the

left of P5. It must be seated flat on the board before soldering.

Install P7, a 3-pin male connector, to the right of P5. The

short ends of the 3 pins are inserted into the board.

Install a shorting jumper onto the two right-hand pins of P7.

At the upper left and right corners of the board are short

jumpers, labeled with ground symbols ( component leads to make 3/4" (19 mm) U-shaped wires for each

jumper (Figure 4-6). Solder the jumpers on the bottom of the board, with the top of the U-shape approx. 1/4" (6 mm) above the board.

Figure 4-6

Locate the outlines for resistors R18 and R19 on the bottom

side of the Control board.

The pads used for R18 and R19 are shared with connectors

J1 and J2, which are labeled on the top side of the board. These connectors are provided with the KAF2 audio filter option. You should not install J1 and J2 or the KAF2 option until after K2 assembly and checkout have been completed.

from discarded component leads as you did above, but keep them flat against the board. Solder the jumpers on the top side.

Install short wire jumpers at R18 and R19. Make the jumpers

). Use discarded

Figure 4-5

Install the following resistors on the bottom side of the board:

__ R12, 820 (GRY-RED-BRN) __ R11, 47 k (YEL-VIO-ORG)

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18 ELECRAFT

op side of C Board

The connectors along the bottom edge of the board (P1,

P2 and P3) will be installed next. It is very difficult to remove them

once they are soldered. Follow all instructions carefully.

Hold the Control board vertically as shown in the side view below (Figure 4-7). The top side of the board--the side with most of the components--should be to the right.

Turn to page 8 and review Figure 3-3, which shows how the Control board plugs into the RF board. P1, P2, and P3 will all be

installed on the top side of the Control board as shown.

Position 6-pin right-angle connector P1 as shown in the side view below (Figure 4-7). Do not solder P1 until the next step. The plastic part of the connector must be seated flat against the PC board, and the pins must be parallel to the board. Do not bend or trim the pins on the bottom of the board.

Top side of PC Board

Figure 4-7

Solder just the two end pins of P1, then examine the placement of the connector. If P1 is not flat against the board, re-heat the solder on the end pins one at a time while pressing firmly on the connector. Once it is in the right position, solder all pins. Do not trim the leads.

Figure 4-8

Install P3, the 20-pin, dual-row right-angle connector (Figure 4-8). Use the same method you used for P1. Do not solder P3 until you are sure that it is seated properly.

Install P2, the 36-pin, dual-row, right-angle connector. Use the same method you used for P1 and P3.

When you install ICs in the following steps, always straighten the leads of each IC first as shown in Figure 4-9. The two rows of pins must be straight and parallel to each other to establish the proper pin spacing for insertion into the PC board or socket.

To straighten the pins, rest one entire row of pins against a hard, flat surface. Press down gently on the other row of pins and rock the IC forward to bend the pins into position as shown below.

Flared

Straight

Figure 4-9

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ELECRAFT 19

Bend two of U2’s corner pins out slightly on the bottom of

Before handling any IC, touch an unpainted,

grounded metal surface or put on a conductive wrist-strap.

Locate U2, an 8-pin IC, part number LM833. (LM833 is the basic part number. There may be an additional prefix or suffix or other markings.) This and all remaining ICs on the Control board are Dual-Inline Packages, or DIPs. Referring to Figure 4-10, identify the notched or dimpled end of the IC. IC pins are counted starting from pin 1 (as shown below) and going counter-clockwise.

the board to hold the IC firmly in place, flat against the top of the board. Find pin 1 and verify that its pad is either round or oval. Once U2 is properly seated, solder all eight pins, using a minimum of solder.

Install the ICs listed below. Bend the pins to hold each IC in place as you did with U2, but do not solder until the next step. The notched or dimpled end of each IC must be aligned with the notched end of its PC board outline.

Note: For U1, the IC type supplied may be either NE602 or SA602.

Notch Pin 1

imple

Pin 1

Figure 4-10

Straighten the leads of U2 (see Figure 4-9).

Install U2 in the orientation shown by its PC board outline, near the upper left-hand corner of the PC board, but do not solder it yet. Make sure the notched or dimpled end is lined up with the notched end of the PC board outline. Even though the outline is covered when the IC is installed, you can still verify that the IC is installed correctly by looking at pin 1. The PC board pad corresponding to pin 1 will be either oval or round.

You may overheat the IC pins or PC pads if you take an excessive length of time to solder. After a few tries, you should be able to solder an IC pin in about 1 or 2 seconds.

__ U1, NE602 __ U3, LM6482 __ U7, 25LC320 __ U8, MAX534 __ U9, LM380 __ U10, LMC660

Check the orientation of pin 1 on each IC by looking at the

associated PC board pads, as before. Then solder all of the ICs.

Locate the microcontroller, U6.

Straighten the pins of U6 (see Figure 4-9). With a large IC such as this, you can hold the IC body at both ends as you re-form each row of pins.

When the microcontroller is pressed in its socket, you must be careful to avoid jamming its pins. Make sure that all pins are lined up with the associated holes in the socket before pressing down on the IC. Watch the pins on both rows as you press down, re-aligning them with the socket holes individually if necessary.

pin 1 on the IC itself is lined up with the pin 1 label near the lower left-hand corner of the PCB outline. Note: The revision label on the IC (usually white) may not be oriented the same direction as the text printed on the IC. Do not use the label as a guide--use the notch or dimple to identify pin 1.

Insert the microcontroller, U6, into its socket. Make sure that

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20 ELECRAFT

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Option Components

All component locations on the Control board should now be filled except for the following:

• C44 (top side of the board near the microcontroller, U6). This

capacitor will not be used.

• J1 and J2 (bottom side). These two connectors are provided for

an audio filter option (KAF2). This option should be installed only after the basic K2 kit has been completed and tested.

Visual Inspection

Nearly all problems with kits are due to incorrectly installed components or poor solder joints. You can avoid these problems by doing a simple visual inspection. A few minutes spent here may save you hours of troubleshooting time.

Make sure there are no components installed backwards. Check all diodes, resistor networks, electrolytic capacitors, and ICs. (The parts placement drawings in Appendix F will be helpful when checking diode orientation.)

Examine the bottom of the PC board carefully for the following (use a magnifying glass if available):

 cold solder joints  solder bridges  unsoldered pins

Resistance Checks

In the table below, "<" means "less than," and ">" means "greater than." When measuring resistances that show a minimum value in the table (such as > 100 k), your resistance reading may be much higher or even infinite. This is typical when using a DMM (digital multimeter). If you use an analog meter you may find that some or all resistance measurements are too low.

Perform the resistance checks listed below to ensure that there are no shorts in the most critical control circuits. (The Control board will be fully tested in a later section.)

Test Point Signal Name Res.

P2 pin 1 12V > 10 k U5, OUT ("5V" pin) 5A > 2 k U4, OUT ("8V" pin) 8A 3 - 7 k

Q1 collector 8 T > 1 M Q2 collector 8R > 1 M

U3 pin 8 12V IN > 10 k

U6 pin 13 OSC1 > 100 k U6 pin 14 OSC2 > 100 k U6 pin 29 DASH 70 - 90 k U6 pin 30 DOT/PTT 70 - 90 k

U8 pin 2 VPWR > 100 k

U8 pin 15 VBIAS-XFIL > 100 k U8 pin 16 VBFO > 100 k

to GND

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ELECRAFT 21

5. Front Panel Board

The Front Panel board includes all of the control and display devices that you’ll use when operating the K2, including the liquidcrystal display (LCD), LED bargraph, push-button switches, and potentiometers. See Appendix D for photos of the completed front panel assembly.

Components

Open the bag labeled FRONT PANEL and sort the parts into groups (resistors, diodes, capacitors, etc.). Observe anti-static precautions when handling ICs and transistors.

Locate the front panel PC board, which is just a bit larger than the Control board. It is labeled "K2 FP" on the top side, in the lower right-hand corner.

SWITCH SPACING TOOL

Figure 5-1

Position pushbutton switches S1 and S2 as shown in Figure 5-2, using the switch spacing tool to set the switch height. Make sure all four legs of each switch are centered in their holes, then gently push each switch until it is resting flush against the switch-spacing tool. (Caution: switch pins are fragile.) Do not solder yet.

Assembly

Your K2’s appearance and operation will be adversely affected if the controls or display are not mounted correctly, and in the indicated sequence. There are also special instructions for installing components on the bottom of the board.

Locate the Spacer Set PC board (Figure 5-1). Using long-nose pliers, carefully break out the pushbutton switch spacing tool and the four backlight LED spacers. Break the material only at the four indicated points. Note: The switch spacing tool doubles as the PC board for the RF probe, which will be assembled later.

S1 S2

Figure 5-2

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22 ELECRAFT

Top of

board

1/16”

Figure 5-3

Figure 5-3 shows a side view of a switch that is properly mounted (spacing tool not shown). The leads of the switches will just be visible on the bottom of the board. Proper switch height is

important for maintaining an even appearance.

Once you’re satisfied that S1 and S2 are seated correctly, solder the leads (on the bottom side of the board). Leave the spacing tool in place until you’ve finished soldering both switches.

Install the remaining switches, S3-S16, using the same technique. When you get to S8 through S16, you may install three switches at a time using the spacing tool.

Install the following 1/4-watt fixed resistors, which are listed in left-to-right PC board order. Solder the resistors after all have been installed. (R13 and a few other parts are part of the SSB adapter option, and are not included in the basic K2 kit. A checklist of these components is provided at the end of this section.)

__ R12, 120 (BRN-RED-BRN) ⇒ __ R10, 33 (ORG-ORG-BLK) __ R9, 220 (RED-RED-BRN) __ R11, 470 (YEL-VIO-BRN) __ R6, 4.7 k (YEL-VIO-RED) __ R7, 4.7 k (YEL-VIO-RED) __ R14, 100 k (BRN-BLK-YEL)

Install the following resistors on the bottom of the board. Solder them on the bottom side. Keep your iron tip away from the bodies of the resistors.

__ R16, 15 k (BRN-GRN-ORG) __ R15, 10 k (BRN-BLK-ORG)

When you install the resistor networks in the next step, you must align the dotted end of the network with the pin 1 label on the PC board outline.

Install the resistor networks listed below (top side of the

board). Double-check pin 1 orientation and values before soldering.

__ RP2, 120, 10 pins (770101121) (dotted end should be near "RP2" label) __ RP1, 100 k, 10 pins (10A1.104G) (dotted end near "RP1" label)

Install and solder the diodes listed below, observing proper

orientation as described in the previous section.

__ D4, 1N5817 __ D5, 1N5817 __ D6, 1N5817

Install and solder the following capacitors. C9 is located on the

bottom of the board and must be soldered on the top side.

__ C1, .047 (473) __ C2, .01 (103) __ C3, .047 (473)

__ C9, .01 (103), on bottom

Install PN2222A transistors at Q1 and Q2, near the middle of the board, and solder. These transistors must be mounted so the lead length above the PC board is less than 1/8" (3 mm) to prevent them from hitting the front panel.

There are two ground jumpers on the Front Panel board, one

at the far left and the other at the lower right, labeled with a symbol. Use discarded component leads to make 3/4" (19 mm) U-

shaped wires for each jumper. Solder them on the bottom side.

Install a 40-pin IC socket at U1, on the bottom of the board. (The IC will be inserted into this socket later.) Orient the notched end of the socket to the left as shown on the PC board outline.

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ELECRAFT 23

The ICs to be installed in the next step are very sensitive to static discharge. Touch a grounded surface before handling each IC. Also note that U4's label will read upside-down (pin 1 at the right) when properly installed.

are oriented correctly (pin 1 associated with a round or oval pad).

__ U4, A6B595KA or TPIC6B595 __ U3, A6B595KA or TPIC6B595 __ U2, 74HC165

steps. This component must be seated flat on the PC board or it will interfere with final front panel assembly. Also, any misalignment will be visible from the front of the K2.

corner or edge that indicates pin 1. Install DS2 as shown by its PC board outline, just to the left of the LCD. Bend two opposite corner pins slightly to hold it to the board, then solder only these two pins.

Install the following ICs. Before soldering, verify that the ICs

The bargraph LED will be installed in the following two

Locate the bargraph LED, DS2. The bargraph has a beveled

Polarizing

nub

Figure 5-4

Install two 3/16" (4.8 mm) diameter x 1/4" (6.4 mm) long round standoffs on the top of the board, adjacent to the microphone jack (Figure 5-5). Use two #4 lock washers between each standoff and the PC board as shown. Secure the standoffs from the bottom side with chassis screws. Recall that "chassis screw" is short-hand for 3/16" (4.8 mm) long pan-head machine screws.

If the bargraph is not perfectly flat against the PC board, reheat the solder on the corner pins alternately while pressing it down. Once it is in the correct position, solder the remaining pins.

Remove any hardware supplied with the microphone jack, J2. The nut and washer will not be used.

Install the microphone jack (J2) in the lower left-hand corner of the board, with its polarizing nub at the top (Figure 5-4). Press the jack down until it is completely flat against the PC board. Recheck the orientation of the polarizing nub before soldering.

Figure 5-5

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24 ELECRAFT

Install another 3/16" (4.8 mm) diameter x 1/4" (6.4 mm) long round standoff on the top of the PC board, on the left side of the large square hole in the middle of the board. The standoff mounting hole is below C2. Use the same hardware as indicated in Figure 5-5, including two #4 lock washers and one chassis screw.

Install two 1/4" (6.4 mm) diameter x 1/2" (12.7 mm) long hex standoffs on the bottom of the board (Figure 5-6). The holes for these standoffs are indicated by large pads on the top and bottom of the board. Use one lock washer and a chassis screw for each standoff. Insert the lock washer between the standoff and PC board.

Bottom of

PCB

Figure 5-6

Install the audio-taper potentiometer, R3, in the lower lefthand corner. (The PCB is labeled "AUDIO" at R3.) Push only on the frame, not the shaft. Make sure that the potentiometer body is parallel to the PC board and is pressed against the board as far as it will go before soldering.

Install the four 5-k linear-taper potentiometers at R1, R2, R4, and R5. (The PC board is labeled "LINEAR" at each pot.) Verify correct positioning as you did in the previous step.

Before installing J1 in the following step, review

Figure 3-3 (page 8) to be sure you have J1 on the correct side of the board.

The front panel attaches to the RF board via J1, a 20-pin single-row female connector. Install J1 on the bottom side of the board (Figure 5-7). Solder just two pins, one at either end.

Bottom side of PC Board

Identify the two different types of panel-mount potentiometers. Four of them are 5-kohm linear-taper types, labeled "B5K". The fifth is an audio-taper type, labeled "A5K". They may be physically identical or have slightly different shafts, body colors, etc.

When you install the panel-mount potentiometers

in the next two steps, do not push on the shafts, which may damage the part. Push only on the metal frame.

Figure 5-7

Re-heat the two end pins and press the connector down until J1

is seated flat against the board, then solder the remaining pins.

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ELECRAFT 25

Install rectangular gray key caps on S1 and S3 so the key caps are parallel to the long axis of the PC board (Figure 5-8). The caps are installed simply by pressing them onto the switch plungers.

Gray keycaps

LED

Square Keycap

Figure 5-8

Install a square black key cap on S7 as shown above.

Install rectangular black key caps on the remaining switches.

Before handling U1, touch an unpainted, grounded

metal surface or put on a conductive wrist-strap.

Straighten the pins of U1, the LCD driver (PCF8566), as you did with the microcontroller on the Control board.

Insert U1 into its socket on the bottom of the board. (This must be done before continuing with LCD installation, since the LCD’s presence will make pressing U1 into its socket much more difficult.) Be sure that U1 is completely seated with no bent pins.

Locate the LCD backlight assembly, which is about 3" (7.5 cm) long. It includes the diffuser and two small LEDs, one at each end.

Do not remove the backing from either side of the diffuser.

diffuser

spacers (2)

Figure 5-9

Position the backlight assembly between the mounting holes labeled D2 and D3 as shown in Figure 5-10. The diffuser must be parallel to and 1/8" (3 mm) above the PC board. To hold the LED spacers and backlight assembly in place, use a rubber band or bend the LED leads out slightly on either end.

spacers (2)

diffuser

2D3

Make sure the LEDs in the LCD backlight assembly are pressed

into the diffuser and are not mis-aligned or loose.

Place two 3/4" (19 mm) long spacers over the leads of each

backlight LED as shown in Figure 5-9.

Figure 5-10

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26 ELECRAFT

Examine the backlight assembly closely to ensure that it is parallel to the Front Panel board and seated as far down on the board as it will go (exactly 1/8" [3 mm] above the board).

Solder D2 and D3. If the backlight assembly is not flat against the PC board, re-heat the LED pins one at a time and press it into place.

Caution: The LCD and its pins are fragile—handle carefully. Do not remove the protective plastic film from the front surface of the LCD until later in this section when the front panel assembly is completed.

to bend the pins.

light. If you see a few very faint lines running across the back, it indicates that a piece of protective film is in place. Remove this piece of film very carefully. (Note: There is also protective film on the front surface, but do not remove it at this time.)

and 24 pins along the upper edge. Place the LCD in its proper position on the board but do not solder yet.

Remove the LCD from its packing materials, being careful not

Look closely at the back surface of the LCD under a bright

The LCD has six pins along its lower edge (three on each side),

The LCD must be seated flat against the diffuser as shown in the edge view (Figure 5-11). If the LCD does not appear to be seated correctly, it may be because the backlight LEDs or spacers are mis-aligned. When the entire assembly is installed correctly, the LCD’s pins will all protrude the same distance from the bottom of the board. (Some units may be supplied with shorter pins that do not protrude at all.)

Solder the four corner pins of the LCD, then re-check the alignment of the LCD assembly. If everything looks correct, solder the remaining pins. LCD pins can be soldered on the top of the board if they do not protrude from the bottom.

Attach two thin, 1/4" (6.4 mm) self-adhesive rubber pads to the bottom side of the Front Panel board in the positions indicated in Figure 5-12. The pads should be placed as close as possible to the corners, but should not hang over on either edge. These pads establish the correct spacing for the Front Panel board and provide some vibration resistance.

Pad

Top Edge

(Bottom of PC Board)

Figure 5-11

Figure 5-12

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ELECRAFT 27

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)

Uninstalled Components

Check off each of the components in the list below, verifying

that they are not yet installed.

__ C4, .01 (103) __ C5, .01 (103) __ C6, .01 (103) __ C7, .01 (103) __ C8, .01 (103) __ R13, 68 k, 1%

__ RP3, 10 k resistor network __ Q3, 2N3906 __ P1 (Mic. Configuration connector, on the bottom of the board)

The unfilled locations (above) are for parts that are provided with the SSB adapter (model KSB2). If you have the SSB adapter kit, you should install them now. Follow the third and fourth assembly steps under Front Panel Board Components in the KSB2 manual (page 16).

Visual Inspection

Make sure there are no components installed backwards. Check all diodes, resistor networks, electrolytic capacitors, and ICs. The parts placement drawings in Appendix F will be helpful in verifying the orientation of diodes.

Examine the bottom of the PC board for solder bridges, cold solder joints, or unsoldered components.

Resistance Checks

Set all potentiometers to their mid-points (approx.).

Perform the resistance checks (to ground) listed below. U1 is

on the back of the board.

Test Point Signal Name Res.

U1 pin 1 IDAT 25 - 35 k U1 pin 2 ICLK 25 - 35 k U1 pin 3 /SYNC 40 - 60 k U1 pin 4 CLK > 50 k U1 pin 5 5A 15 - 40 k

U1 pin 6 - 11 Ground 0

U1 pin 12 2V 9 - 11 k

U1 pin 13 - 40 LCD segments > 50 k

J1 pin 1 AF gain 1 > 1 M J1 pin 2 AF gain 2 > 1 M J1 pin 3 AF gain 3 > 1 M J1 pin 4 DOT/PTT > 1 M J1 pin 5 MIC AF > 1 M J1 pin 6 ENC B > 50 k J1 pin 7 AUXBUS > 1 M J1 pin 8 Ground 0

J1 pin 9 SR DOUT > 50 k J1 pin 10 SR DIN > 50 k J1 pin 11 SR WRT > 50 k J1 pin 12 SR CK > 50 k J1 pin 13 ENC A > 50 k J1 pin 14 SR RD > 50 k J1 pin 15 VPOTS 10 - 60 k J1 pin 16 ICLK 25 - 35 k J1 pin 17 IDAT 25 - 35 k J1 pin 18 5A 15 - 40 k J1 pin 19 RF gain 1.5 - 3.5 k J1 pin 20 Ground 0

to GND

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28 ELECRAFT

Front Panel Final Assembly

Locate the front panel chassis piece. Place it on a soft cloth

to protect the finish and labeling.

In the following step, the paint masking material will be removed from the inside of the front panel. The masking material is usually green, but may appear gray because of paint overspray. DO NOT remove the masking material from the other chassis pieces at this time.

surface during painting. If masking tape (usually green in color) is still present, you'll need to remove it. The holes that are masked are in the four corners, along the top and bottom edges.

Masking tape should be removed as follows:

 Using a blunt instrument such as a ball-point pen, push on the

 Peel the tape completely off, using a sharp tool if necessary. Be

Some holes in the front panel were masked on the inside

tape through a hole until the tape begins to lift away from the surface.

careful not to nick or scratch the outer surface of the panel.

Locate the green plastic bargraph filter and two pieces of

double-backed tape. These items will be found in a small bag.

Caution: The adhesive on the double-backed tape is very strong. Once you position the tape on the green filter, you will not be able to remove it. Be very careful to align the tape with the long edges of the filter as explained below.

of tape. Attach the tape to the long edges of the green filter (Figure 5-13). Be careful not to get any adhesive on the center portion of the filter, since it might be visible after installation.

Remove the white paper backing from one side of each piece

align edge of tape with filter

After removing any masking tape, place the front panel chassis piece face-down, with the large, round microphone jack hole on the right.

Figure 5-13

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ELECRAFT 29

Remove the brown paper backing from the other side of each piece of tape, then turn the filter/tape assembly adhesive-side down. Carefully center the green plastic filter over the inside of the bargraph LED hole (Figure 5-14).

reen Film

ape

Figure 5-14

Turn the front panel face up.

Position the clear plastic LCD bezel over the LCD and bargraph holes as shown in Figure 5-15. The bezel goes on the outside of the panel.

Secure the bezel with four 2-56 screws (stainless steel) as shown in Figure 5-15. Tighten the 2-56 screws only the

amount needed to hold the bezel to the front panel. Overtightening may crack the bezel or strip the threaded holes in the panel.

LECRAF T K2 TR AN SCEIVE R

2-56 Scr ew (4) LCD Bezel

Figure 5-15

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30 ELECRAFT

Remove the insulation from four 1.5" (38 mm) lengths of

green hookup wire.

Install the bare wires on the bottom of the front panel PC board, using the four pads below the large rectangular hole (Figure 5-16).

Solder and trim the wires on the top side of the board. The wires will be connected to the optical encoder, Z1, in a later step.

Figure 5-16

Insert the front panel PC board assembly into the front panel. The pushbutton switch caps on both sides of the LCD should protrude slightly as shown in the side view, Figure 5-17a.

Note: the board/panel assembly will not be rigidly held in place until it is mated with the RF and Control boards in a later section.

(a)

Figure 5-17

(b)

Remove the protective plastic film from the face of the LCD.

Be careful not to scratch the glass. Caution: Do not peel off the

LCD glass, just the thin protective film. The LCD will not be usable if you lift the glass itself.

A 1/4" (6.4 mm) standoff on the PC board should now be visible through the hole just to the left of the encoder mounting hole. Secure the panel to this standoff using the 4-40 x 3/16" (4.8 mm) flat-head screw as shown in Figure 5-17b.

Remove the hardware from the shaft of the encoder, Z1, and discard the lock washer, which will not be used. Insert the encoder through the hole in the Front Panel board (Figure 5-18a).

Cut 1/8" (3 mm) off the end of each of the encoder's four connector pins.

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ELECRAFT 31

Attach the encoder to the inside of the front panel using the nut and flat washer only. Figure 5-18 shows the side view (a) and front view (b) with encoder properly installed. The encoder has a small metal tab near the shaft that will only allow it to be installed one way. Do not over-tighten the nut. (Note: the green encoder bushing is metal, not plastic.)

(a)

Figure 5-18

Attach the four encoder wires you installed earlier to the matching pins on the back of the encoder. Each wire should be wrapped securely around the base of its matching pin, with no slack in the wire. Trim and solder the wires, making sure they aren't shorting to each other or to the encoder body, which is conductive.

(b)

Attach small knobs to the potentiometer shafts, starting with the KEYER and POWER controls. Each knob's two set screws can be tightened using the small Allen wrench (.050", 1.3 mm). The knobs should be mounted as close as possible to the panel without touching it. Align the pointers per panel labeling.

Locate the 1" (25 mm) dia. by 1/16" (1.6 mm) thick felt washer, and place it over the encoder nut (Figure 5-19). The washer should be seated on the front panel, with the nut inside it.

Figure 5-19

Place the large knob on the encoder shaft. Push the knob on until it just touches the felt washer. If the knob does not spin freely, move it out slightly. If the knob is not contacting the felt washer at all, it may "drift" slightly once it stops spinning.

Set all potentiometers to midway in their rotation.

In the next step, a small knob may fit too tightly onto its potentiometer shaft. If so, rotate the shaft until it bumps up against one of its stops, place the knob at the top of the shaft, and rotate it slowly in the same direction while gently pressing it down.

Using the larger Allen wrench (5/64", 2 mm), tighten the two

set screws alternately, in small increments.

At this point, the pushbutton switches may not all protrude an equal distance. The switch height will become equalized once the front panel assembly is mated to the RF board in a later step.

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32 ELECRAFT

6. RF Board

Most of the K2’s receiver and transmitter circuits are located on the RF board, including filters, oscillators, and RF amplifiers. The front panel and Control boards plug into the RF board, and the chassis pieces are designed to form a tight enclosure around it (see photos in Appendix D). In addition, many option boards plug directly into the RF board to minimize wiring.

Assembly and testing of the RF board is broken into three parts:

Part I: The DC and control circuits are installed so that the front panel and Control boards can be plugged in and tested. The I/O controller (U1 on the RF board) is also installed and tested at this time. Once this phase of assembly is completed, you’ll have the K2’s built-in test equipment available for testing and aligning the remaining circuits.

Part II: Synthesizer and receiver components are installed and tested. By the end of Part II you’ll have the K2 receiving on 40 meters.

Part III. Transmitter components and all remaining filter components are installed. The K2 is then aligned on all bands.

Components

Review anti-static precautions before handling transistors

or ICs.

Open the bags labeled RF and sort the components into related groups. In later steps you’ll sort some of the components according to value to reduce the likelihood of assembly errors.

Locate the RF board and place it in front of you with the component side up (the side with most of the parts), and the front edge facing you (the edge with the irregular cutouts). Throughout this section we’ll refer to the different areas of the board in terms of their proximity to you. For example, "front-left" means the corner closest to you on the left.

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ELECRAFT 33

Take a moment to familiarize yourself with the RF board using Figure 6-1 to identify the major sections. If you flip the board over you’ll see that there are a few components on the bottom of the board, primarily in the transmitter section.

T-R Switch

Band-Pass XMTR Low-pass

Filters Filters

U1 (I/O Controller)

Synthesizer RCVR

Figure 6-1

Turn the board over and install 2-D fasteners at five locations on the bottom of the RF board as shown in Figure 6-3. Secure each fastener from the top side of the board using two chassis screws (black, 3/16" [4.7 mm]) and two #4 lock washers.

Holes offset from center

Figure 6-2

(Bottom of board)

2-D Fasteners

(5)

Assembly, Part I

Locate a 2-D fastener and hold it vertically as shown in Figure 6-2. Looking at a side with two holes, note that the holes are offset from the center. When you install the fasteners in the following step, be sure to position them so that the holes in the fastener are shifted in the same direction as the holes in the PC board outlines on the bottom of the board.

1/4"

Standoffs

Figure 6-3

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34 ELECRAFT

Make sure that the 2-D fasteners on the edges line up with the edge of the PC board and do not hang over. If they hang over or do not match their component outlines, they are installed backwards.

Install two 3/16" (4.8 mm) diameter by 1/4" (6.4 mm) long round standoffs on the bottom of the board at the locations identified in Figure 6-3. Secure these standoffs from the top side with chassis screws and #4 lock washers. Do not put lock washers between the bottom of the board and the standoffs.

Turn the board back over to the top side. Install the 28-pin IC socket at U1, near the middle of the board (Figure 6-1). The notched end of the socket should be at the left. Make sure the socket is flat against the PC board before soldering. (U1 itself will be installed in a later step.)

In the following steps you will install the latching relays (K1-K17). Relay pins must not be bent or trimmed, even after placement on the PC board, as this may cause unreliable mechanical operation. Since the pins cannot be bent to hold the relays on the board, an alternative assembly technique using a flat surface must be used. For this technique to work, the relays must be installed before any of the taller components.

Place relays K1-K17 on the top side of the RF board. One end of each relay has a heavy line printed across the top to indicate the pin 1 end. This end must be matched with the same end of the relay’s PC board outline. Do not solder the relays yet.

When all of the relays have been placed on the board, lay a flat object such as a book or piece of cardboard on top of the relays to keep them in place, then flip the board over.

Solder only two pins (at opposite corners) on each relay. Do

not bend or trim relay leads.

Install R1 and R2 (220 ohms, RED-RED-BRN), near the back

left corner of the board.

To avoid stray signal coupling, all capacitors on the RF board must be mounted as close to the PC board as possible (without damaging the leads or their epoxy coating).

Install C1 and C2 (.001 µF, "102"), which are on the left edge.

Install electrolytic capacitors C105 and C106 (2.2 µF), located

near the front-left corner.

Install R35 and R36 (82, GRY-RED-BLK) just to the right of

C105.

Install R115 (.05 ohms, 3 watts) at the front right corner of

the board. Form the leads as indicated by the component outline.

Install the following components to the left of R115.

__ C111, 2.2 µF electrolytic ("+" lead goes into the square pad) __ R113, 82 (GRY-RED-BLK)

Install the internal speaker connector, P5, which is a 2-pin connector like that shown in Figure 4-5. P5 is mounted near the on-off switch (S1). Position the connector as shown by its component outline, with the vertical locking ramp toward S1.

Install high-current diodes D10 and D12 (large black body), located near the right edge of the board:

__ D10, 95SQ015 __ D12, SB530 (a 1N5821 may be substituted for D12)

Install the following components near D10:

Turn the board back over and verify that all of the relays are

in the correct orientation and are seated flat on the board.

Solder all of the remaining relay pins.

__ C77, .001 (102) __ C196, .047 (473) __ R69, 100 k (BRN-BLK-YEL) __ R66, 2.7 k (RED-VIO-RED)

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ELECRAFT 35

Install the self-resetting fuse, F1, near D10. F1 is yellow and

looks like a square-bodied capacitor. One side is labeled "G300".

Install the key jack, J1, at the back-left corner of the board. Before soldering, make sure that the jack is aligned with its PC board outline.

Install the headphone jack, J2, on the small board extension near the front left corner. The pins on J2 are not very long, so they will be nearly flush with the bottom of the board. Solder the pin closest to the front edge first (ground), then verify that the jack is seated flat on its plastic nubs before soldering the remaining pins.

Install the power switch, S1, at the right front corner. (S1's key cap will be installed later.)

Install the DC input jack, J3, at the back right corner. The 3 leads on the jack must be lined up with the slot-shaped holes in the component outline. If the holes are a tight fit, press firmly until the connector snaps into position.

Install the antenna jack, J4 (BNC), just to the left of J3.

Install the following components near U1 (at the middle of the board). You may need to confirm the part number of U2 (78L06), since it is easy to confuse it with U8 (78L05). Use a magnifying glass if necessary.

__ U2 (78L06) __ C139, 0.1 (104) __ C140, .001 (102) __ R64, 100 (BRN-BLK-BRN)

Install the ceramic resonator, Z5, near U1. (The ceramic resonator looks like a capacitor with three pins.)

Install D8 and D18 (1N4148), on the bottom of the board, toward the right edge. Make sure the banded end of each diode is aligned with the band on its component outline.

In the steps that follow you’ll install the connectors that mate with the control and Front Panel boards. These connectors must be installed properly to ensure reliable mechanical connection. They are very difficult to remove once installed, so follow all instructions carefully. Review Figure 3-3 (page 8) for correct

placement.

Install the 6-pin, single-row female connector, J6, which is just left of the power switch. It must be seated vertically on the board and must not be tilted (Figure 6-4). Solder just one pin near the center of J6.

Figure 6-4

If J6 does not appear to be completely flush with the board, re-heat the soldered pin and press down. Once it is installed correctly, solder the remaining pins.

Install the 20-pin, dual-row female connector, J8, near the front left corner of the board. Use the same technique you used for J6. This connector must be seated flush with the board before soldering.

Install R65 (10 k, BRN-BLK-ORG) on the bottom of the

board, near U1.

Install 36-pin dual-row female connector J7 in the same manner as J6 and J8.

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36 ELECRAFT

(

)

Position 20-pin male right-angle connector P1 on the bottom of the board (Figure 6-5), but do not solder P1 yet. Review Figure 3-3 (page 8) for correct placement. The short ends of the bent pins are inserted into the holes, and the long ends must be parallel with the board.

Top of board

Front edge

Before handling U1, touch an unpainted, grounded

metal surface or put on a conductive wrist-strap.

Install the I/O controller, U1 (PIC16C72 or 16F872), in its socket (near the middle of the board). Be sure to align the notched or dimpled end of U1 with the notched end of the socked (to the left). Make sure U1 is seated as far down in the socket as it will go and that none of its pins are bent. Note: The revision label may not be oriented in the same direction as the text printed on the IC. Use the notch or dimple to identify the pin 1 end.

Visual Inspection

Figure 6-5

Solder just the two end pins of P1.

Look closely at P1 to make sure that its plastic support is pressed down as far as it will go, and that the pins are parallel to the board. If not, re-heat the soldered ends while pressing it into place. Once it is seated properly, solder the remaining pins.

To the left and right of the I/O controller, U1, you’ll find two short jumpers labeled "

3/4" (19 mm) U-shaped ground jumpers at these locations as you did on the control and Front Panel boards. Use discarded component leads.

On the bottom of the board you’ll find two additional ground jumpers, one near the middle and the other near the back edge. Install U-shaped ground jumpers in these two locations.

" (on the top side of the board). Install

Examine the RF board carefully for unsoldered pins, solder

bridges, or cold solder joints.

Set switch S1 on the RF board to the "OFF" position. (Plunger

OUT is OFF, plunger IN is ON.)

Resistance Checks

Perform the following resistance checks.

Test Point Signal Name Res.

R115, right end (near S1

U1 pin 1 6V > 500 ohms U1 pin 4 K13 control > 20 k

U1 pin 9 OSC1 > 20 k U1 pin 10 OSC2 > 20 k U1 pin 28 AUXBUS > 20 k

R1 (end near R2) DOT/PTT > 1 M R2 (end near R1) DASH > 1 M

12V IN > 500 ohms

to GND

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ELECRAFT 37

When working with the side panels in the following steps,

place a soft cloth on your work surface to protect the paint.

Locate the two side panels. Remove any masking tape from the panels using the same technique described in the Front Panel section, taking care not to scratch the outer surfaces.

Arrange the two panels as shown in Figure 6-6, and verify that they are mirror images of each other. The 2-D fasteners to be attached in the next step go on the inside surface, which has bare aluminum areas that were masked during painting. (Note: the actual size and shape of masked areas may vary.)

Left Side Panel (inside surface)

Right Side Panel

(inside surface)

Holes offset away from

anel

Figure 6-7

Install two 2-D fasteners on each side panel at the locations indicated by small rectangles in Figure 6-6. Use one chassis screw to hold each fastener to the side panel (see Figure 6-7). The two unused holes on each fastener must be offset away from the side panel.

Figure 6-6

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38 ELECRAFT

Locate the tilt stand, which can be found in the

Since the K2 chassis is made up of a number of individual panels and fasteners, you may need to loosen the fasteners and readjust them once or twice during assembly.

Attach the side panels to the RF board using two chassis screws per side panel. The side panels are attached to the 2-D fasteners that are already in place on the RF board. Figure 6-8 shows the approximate location of the two screws used to secure the right side panel.

MISCELLANEOUS component bag. It has three parts: two oval feet and a tilt bail (Figure 6-9). Note: the screws that will be used to hold the tilt bail in place are not the black anodized type. They are standard steel/zinc plated screws, 7/16" (11 mm) long, so you won’t confuse them with the 3/8" (9.5 mm) or 1/2" (12 mm) black screws.

Remove any masking tape from the bottom cover chassis

piece.

Each oval foot has a notch into which the bail will be inserted. Install one of the oval feet on the bottom cover using two 7/16" (11 mm) 4-40 screws, #4 lock washers, and 4-40 nuts. The notch in the foot should be facing inwards (toward the other foot). The nuts and lock washers go on the inside of the bottom cover.

Install the tilt bail, then the second oval foot. The bail should be compressed firmly between the two feet. You may need to adjust the positions of the feet slightly before tightening the hardware.

Make sure the two feet are at exactly the same distance from the front edge of the bottom cover. If they are not equally spaced, the tilt stand may "rock" when in use.

Figure 6-8

Figure 6-9

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ELECRAFT 39

Turn the RF board/side panel assembly upside down. Check for

any untrimmed component leads on the bottom of the board.

Position the bottom cover as shown in Figure 6-10, then secure it using six chassis screws. (The heat sink and rear feet will not be installed until Part III when the transmitter is assembled.)

With the entire assembly still upside down or resting on one side panel, plug the front panel assembly into the RF board (Figure 6-10). Align the two assemblies so that connector J1 on the bottom of the front panel PC board mates with P1 on the bottom of the RF board. The arrow in Figure 6-10 shows the approximate location of P1 on the RF board.

Once the front panel assembly is in place, the headphone jack (on the RF board) should be just flush with the front panel. The small rubber pads in the upper corners of the Front Panel board should be just touching the 2-D fasteners on the RF board. If this is not the case, the front panel must be pushed farther in.

Secure the front panel to the side panels and RF board using 4 chassis screws. (Refer to the photos in Appendix D.) You may need to make slight adjustments to the 2-D fasteners at the top edge.

Figure 6-10

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40 ELECRAFT

Plug the Control board assembly into the RF board, with the component side of the Control board facing backwards. (Refer to the photos in Appendix D.) All three connectors on the Control board must be lined up with the three connectors on the RF board at all pins.

Make sure the Control board is pushed as far down as it will go; it should be flat against the RF board along its entire edge, with all three connectors properly mated.

If the Control board does not plug in easily, you may have

one or more connectors installed incorrectly.

The long-handled Allen wrench can be used to extract the Control board (Figure 6-11). To the left of J7 on the RF board you’ll find the label "LIFT" near a hole at the base of the Control board. Insert the Allen wrench into this hole, then rest the knee of the wrench on the nearby screw head. Pry the board up with the wrench while guiding the board out at the top.

Once you have tried the Control board extraction technique described above, plug the Control board back in for the tests that follow.

Secure the front panel and Control boards together using two chassis screws (Figure 6-12). The upper left and right corners of the Control board may be touching the 2-D fasteners, or there may be a small gap.

Long-handled

allen wrench

Figure 6-11

Figure 6-12

Push the black keycap onto S1’s plunger until it snaps into place. Test S1’s action (push on, push-off). Leave the switch in the OFF position (out).

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ELECRAFT 41

Alignment and Test, Part 1

In this section you’ll test most of the circuits on the Control board and front panel. Along the way you’ll become familiar with basic operation of the K2, including use of the front panel switches, display, and menu.

Before proceeding with initial test, turn to the first page of the Operation section of the manual to familiarize yourself with the K2’s front panel layout. Do not turn on power to the K2 at this

time.

The Tap/Hold Rule

Each of the push-button switches on the front panel has two functions, one activated by a TAP (short press) and the other activated by a HOLD (long press, about 1/2 second). The upper label on each switch shows the TAP function (white lettering), and the lower label shows the HOLD function (yellow lettering). To highlight this in the text, we use two different typographical styles to identify switches:

Initial Test

If any test or alignment step fails, refer to the

Troubleshooting section (Appendix E).

Set the controls on the front panel as follows:

AF GAIN: midway (12 o’clock) RF GAIN: maximum (clockwise) KEYER: midway POWER: minimum (counter-clockwise) OFFSET: midway

T A P and H O L D .

Locate P7 on the Control board. A shorting jumper should be

installed onto the two pins of P7 nearest the "P7" label.

For the remaining test and alignment steps, you’ll need a wellregulated 12-14 V power supply or a battery. A power supply rated at 300 mA or more of output current will suffice for the tests in Parts I and II, but higher currents (3-3.5 A) will be needed for transmitter tests in Part III.

If your power supply or battery does not already have a plug that mates with the power jack (J3), use the supplied mating plug and prepare a suitable power cable. The center lead of the plug is positive (+).

Make sure the K2 is turned OFF (power switch S1 out). Plug your power supply or battery into J3 on the rear panel.

Fold the tilt stand out to improve the viewing angle if desired.

If you see or smell smoke when you turn the K2 on for the

first time, turn off power and disconnect the power supply immediately. Normally, you should hear the relays being reset by

the I/O controller. Next, nonvolatile configuration memory (EEPROM) will be initialized. This process takes approximately 10 seconds. During this period, you should see I N F O 2 0 1 on the LCD. Displays of this kind are referred to as "INFO messages," and are used to alert you to possible problems. In this case, the info message is just a reminder that EEPROM has been initialized.

Turn on the K2 using S1. After about 10 seconds, you should see the default K2 frequency display for 40 meters: 7 1 0 0 . 0 0 c . The letter C indicates CW mode. The annunciator for VFO A will also be turned on. (If you see any other INFO messages or the display does not come on, refer to Troubleshooting.)

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42 ELECRAFT

Turn the K2 off and wait for a few seconds, then turn it back

on. The display should now show E L E C R A F T for about two seconds, followed by the frequency display. Now that the EEPROM is initialized, this is the display you should always see on power-up. The "R" and "T" in "ELECRAFT" appear in lower-case letters due to the limitations of the seven-segment LCD characters.

Tap the D I S P L A Y switch once to select voltage/current

display. The display should now show something similar to this:

E 1 2 . 0 i 0 . 0 6

This would indicate that the power supply voltage (E) is about 12.0 V, and the supply current (I) is about 60-80 mA.

Optical Encoder Test

Tap the D I S P L A Y switch to return to the frequency display.

Turn the VFO knob in both directions and verify that the

displayed frequency changes accordingly.

Tap the

tuning rate, and repeat the VFO test at each rate.

R A T E switch to the right of the knob to change the

Relay Test

Tap the P R E / A T T N switch three times. You should hear relays

switch each time.

RF Probe Assembly

The Switch Spacing Tool used during Front Panel can now be used as the PC board for the RF probe. All parts for the probe, including a ground alligator clip, 2 feet of RG174 coax, and banana plugs for a DMM, are supplied with the kit. You can assemble the probe at any time, using the instructions on page 9 of Appendix E.

Voltmeter Probe Assembly

If you do not have a DMM (digital multimeter), you can use the simple DC voltage probe shown below in conjunction with the builtin voltmeter. The crimp pin and 2-pin housing can be found in the MISCELLANEOUS components bag.

Assemble the voltage probe as shown in Figure 6-13 using green-insulated hookup wire. No ground connection is needed since you will be measuring voltages inside the K2.

Hookup wire,

12” (0.3m)

Housing

Tap the B A N D + switch. You should see the band change to the

next higher band. At the same time, you’ll hear one or more relays.

Tap the B A N D + switch 7 more times to verify that you hear

relays being switched with each band change. Note: The 1.8 MHz (160 m) and 5 MHz (60 m) bands will not appear in the band list unless the associated options are installed. This can be done only after assembly and alignment have been completed.

The supply voltage reading will reflect a small drop across D10, the reversepolarity protection diode, typically 0.1 V on receive. Accuracy of both current and voltage readings is about +/- 5%.

Tinned lead,

Crimp pin

0.5” (13mm)

Figure 6-13

Plug the voltage probe assembly into P5 on the Control board. The probe should be oriented so that the hookup wire is connected to the (+) side of P5.

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ELECRAFT 43

Tap

Move the voltage select jumper (Control board, P7) toward

P5. Select voltage/current display mode using the

D I S P L A Y switch.

The voltage reading on the LCD should go to 0 0 . 0 .

To test the voltage probe, touch the tinned end of the hookup wire to pin 1 of the I/O controller, U1 (RF board). The voltage displayed on the LCD should be approximately 6 V.

Return the voltage select jumper to the "12 V" position.

M E N U again to bring up the menu. Turn the VFO knob now,

and you’ll see the other menu entries and their parameters scroll by. (You can also tap the

B A N D + or B A N D - switches to scroll

through menu entries.) Scroll the menu until you see

I N P H A N D

This menu entry is used to select the keying device. H A N D means that the key jack is configured for a hand key or external keyer.

Note: Always disconnect the voltage probe when it is not in use. It may cause shorts or noise pickup if left inside the K2 during normal operation

Menu Tutorial

We’ll present a brief tutorial on using the menu here. A complete list of menu functions can be found in the Operation section.

Tap the

This is the sidetone level menu entry. 0 4 0 is the associated

parameter, in this case the sidetone volume setting. The row of annunciators under S T L serves as an underline, indicating that

turning the VFO knob will change the menu entries.

Tap the voltage/current display, depending on what display mode was

selected when you entered the menu.

M E N U switch on the K2. The first entry will be displayed:

S T L 0 4 0

M E N U switch again and you’ll return to the frequency or

Press and hold the

E D I T switch for 1/2 second to activate the EDIT

function. (Remember the TAP/HOLD rule: when you HOLD a switch in, you activate the function indicated by the lower label on the switch.) The display should now show:

I N P H A N D

Notice that the underline has moved to the parameter (H A N D ). This tells you that you’re in EDIT mode, and that turning the VFO knob will now change the parameter for the current menu entry. You can also change the parameter using

B A N D + and B A N D - .

Turn the VFO knob now to see the various keying input selections. P D L n and P D L r configure the key jack for a keyer paddle, wired for either normal (tip = dot) or reverse (tip = dash) operation.

Tap the

M E N U switch again to exit EDIT mode. The underline

should return to the menu entry.

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44 ELECRAFT

Using the Calibration Functions

Scroll the menu until you see C A L O F F . This is the entry point into the calibration sub-menu, which you’ll be using during alignment.

Enter EDIT mode by holding to the O F F parameter. Then turn the VFO knob to see the various

C A L functions, including F C T R (frequency counter), C U R (transmit current limiting) S H I / S L O (S-meter calibration), F I L (crystal filter configuration), and P L L (VFO calibration).

Once you select a C A L function, holding function. The selected C A L function remains active until you tap

M E N U again, which returns you to the menu. Another tap of M E N U

returns you to the normal K2 display.

In the following section you’ll activate the C A L F C T R (frequency counter) function. For now, just tap

twice to return to the normal display.

E D I T as before, moving the underline

E D I T again activates the

M E N U once or

Frequency Counter Probe Assembly

In the bag labeled MISCELLANEOUS you’ll find the components for the frequency counter probe (Figure 6-14). These components include a 10 pF axial-lead capacitor, two crimp pins, a 2-pin housing, and a 1-pin male connector (probe tip).

Separate the braid from the center conductor at both ends. Remove 1/4" (6 mm) of insulation from each center conductor. At one end, cut the braid off completely right at the coax jacket (a ground connection will not be needed for frequency measurements). The braid should be twisted into a fine bundle at the other end.

Solder crimp pins onto the center conductor and shield at the housing end of the cable. Solder quickly, so that the heat from soldering does not melt the center insulator of the coax and cause a shield-to-center short.

Insert the pins into the crimp housing as shown in Figure 6-14. They should snap into place. Each crimp pin has a small tab on the back that latches into a hole in the housing.

Trim the leads of the 10 pF axial-lead capacitor down to 1/4" (6 mm). Solder one end to the center conductor of the coax cable.

Probe

tip

10pF

eat-shrink tubing (2 layers)

RG-174 Coax,

7” (18cm)

Crimp housing

Cut a 7" (18 cm) length of RG-174 cable and carefully remove 1/2" (13 mm) of the coax jacket from each end. Be careful not to nick the braid.

Figure 6-14

Solder the probe tip to the other end of the 10 pF capacitor.

Slip a 1" (2.5 cm) length of the larger size heatshrink tubing onto the probe tip components. Shrink the tubing using a heat gun. (You can also use a soldering iron, but avoid melting the tubing.)

Add a second, identical length of heatshrink tubing on top of the first, then shrink it. This strengthens the assembly.

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ELECRAFT 45

Plug the frequency counter probe assembly into P6, which is at the far left end of the Control board (as viewed from the front of the transceiver). The connector can only be plugged in one way.

Turn on the K2 and tap M E N U to bring up the menu, then scroll to the C A L menu entry. Hold

parameter until the display shows C A L F C T R . Hold

E D I T , then scroll the C A L

E D I T again

to activate the frequency counter function of the C A L sub-menu. The LCD should show 0 0 0 0 . 0 0 . (The frequency counter circuitry is sensitive, so it may pick up a stray signal and show it on the display.)

To test the counter, you can read the frequency of the 4 MHz oscillator on the Control board. Touch the counter probe tip to the left side of trimmer capacitor C22, which is just below the 18C452 microcontroller. The LCD should now read very close to 4 0 0 0 . 0 0 .

Remove the frequency counter probe.

Audio Amplifier and Tone Generator Test

Plug in a pair of low-impedance (4 to 32 ohm) headphones, stereo or mono.

Tap M E N U and scroll to the sidetone level menu entry (S T L ). Hold

clean 600-Hz audio tone. Turning the VFO knob should vary the volume.

E D I T to activate the sidetone. You should now hear a

Tap M E N U to turn off the sidetone, then scroll up to the

sidetone pitch menu entry (ST P) using the VFO knob or by tapping the

B A N D + switch. The display will show

S T P 0 . 6 0

This indicates that the sidetone pitch is set for 0 . 6 0 kHz (600 Hz). Hold

E D I T to turn on the sidetone, then vary the VFO knob. The

pitch of the sidetone should change to match the display.

Keyer

In the following steps you’ll test the keyer (audio tone generation only). This tests the keyer jack, speed control, and potentiometer read circuits, including the A-to-D converter on the microcontroller.

Tap M O D E until C is displayed at the right end of the LCD,

indicating CW mode.

Plug a keyer paddle into the key jack. The plug must be stereo (2 circuit). A mono plug will key the transmitter continuously. (A mating stereo plug for the keyer jack is supplied with the kit.)

Using the menu’s I N P entry, set up the keyer input for either P D L n or P D L r as described previously.

Adjust the KEYER control. As soon as you turn it, the display should show the keying speed (approx. 9-50 WPM).

Notice that turning the AF GAIN control does not affect the sidetone volume. The sidetone is injected into the AF amplifier after the volume control, so AF GAIN affects only the receiver volume.

This is not a valid indication of how well the 4 MHz oscillator is calibrated, since this oscillator is used as the reference for the frequency counter itself. The 4 MHz counter will be calibrated in a later step.

While listening with headphones, test the keyer paddle to

verify that both dot and dash are working.

Note: No sidetone will be generated when LSB or USB mode is selected (L or U).

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46 ELECRAFT

Setting the AGC Threshold

Make sure the RF GAIN control is rotated fully clockwise.

Locate potentiometer R1 on the Control board (right side, as

viewed from the front of the K2).

Set your DMM for DC volts. Connect the (-) lead of the

DMM to one of the ground jumpers or to the K2 chassis ground.

Touch the (+) lead to pin 5 of U2 on the Control board. (U2 is

located just above trimmer R1. Pin 5 is the pin nearest diode D1.)

Adjust R1 for a reading of 3.80 volts on the DMM. This is the

suggested setting, but it can be adjusted later to suite the operator.

The S-meter must be realigned anytime the AGC

threshold setting is changed. S-meter alignment is covered in the following steps.

S-Meter Alignment

Using the menu, select the C A L S L O function (S-meter

zero). Hold

Turn the VFO knob until you see only the left-most segment of the LED bargraph lit. Then turn the knob a bit more clockwise until this LED just turns off.

E D I T a second time to activate it.

Turn the RF GAIN control back to its full clockwise position.

Exit the C A L S H I function by tapping M E N U .

Bargraph Current Test

In the following steps, you’ll test the current measurement circuit by using the bargraph LEDs to establish a known current drain.

Enter the menu and verify that G R P H (LED bargraph mode)

is set to D O T , not to B A R or O F F .

Set the RF GAIN control for minimum gain. Segment 10 of the LED bargraph should now be on if you have done the S-meter adjustment as described above.

Using the menu, select the L C D menu entry. Change the parameter from N I T E to D A Y . At this point you’ll see the LCD backlight turn off, and segment 10 of the LED bargraph will become much brighter.

Exit the menu and tap D I S P L A Y to switch to voltage/current mode. Write down the voltage and current readings.

Use the menu to change the G R P H mode to B A R . All 10 segments of the LED should now be on.

Exit the menu and check the current. It should now be about

0.16 to 0.18 amps higher.

Exit the C A L S L O function by tapping M E N U . Enter the

menu again and select C A L S H I (S-meter full-scale sensitivity).

Turn the RF GAIN fully counter-clockwise (minimum gain). Adjust the VFO knob until you see segment 9 of the bar graph lit, then turn it a bit more counter-clockwise until segment 10 just turns on (right-most segment).

Use the menu to change G R P H to D O T , and L C D to N I T E .

The combination of L C D D A Y and G R P H B A R can

result in high peak current drain on receive. When operating from a battery, D O T or O F F should be used to conserve power. More information about conserving power is provided in the Advanced Operating Features section.

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ELECRAFT 47

Assembly, Part II

In this section you’ll install the components for the synthesizer and receiver circuits. Most of the components to be installed are on the front half of the board (see Figure 6-1). After all of the parts are installed, individual stages will be aligned and tested. Detailed troubleshooting procedures are provided in the Troubleshooting section should you need them (Appendix E). The supplied RF probe will be very useful if you need to do signal tracing. RF probe assembly instructions start on page 9 of Appendix E.

In some steps a large number of components will be installed, then soldered as a group. Check for unsoldered leads after completing each group. A final complete check will be done later.

Remove the screws holding the Control board to the Front Panel board, then unplug the Control board. To avoid damaging any Control board components, use the long-handled Allen wrench as described in Part I.

Remove the bottom cover (six screws).

Remove the screws from the front panel assembly and unplug it from the RF board. Pull it straight out from the bottom edge, near the middle of the panel. This may be easier to do with the transceiver sitting on its right side so that you can steady it with one hand and pull with the other.

__ R9, 100 k (BRN-BLK-YEL) ⇒ __ R16, 100 k (BRN-BLK-YEL) __ R10, 470 (YEL-VIO-BRN) __ R31, 10 k (BRN-BLK-ORG) __ R32, 10 k (BRN-BLK-ORG) __ R33, 15 k (BRN-GRN-ORG) __ R30, 120 (BRN-RED-BRN) __ R28, 27 k (RED-VIO-ORG) __ R20, 270 (RED-VIO-BRN) __ R21, 100 k (BRN-BLK-YEL) __ R22, 3.3 M (ORG-ORG-GRN)

__ R25, 2.7 k (RED-VIO-RED) __ R24, 2.7 k (RED-VIO-RED) __ R15, 33 (ORG-ORG-BLK) __ R14, 10 k (BRN-BLK-ORG) __ R13, 10 k (BRN-BLK-ORG) __ R12, 560 (GRN-BLU-BRN) __ R17, 100 k (BRN-BLK-YEL) __ R11, 560 (GRN-BLU-BRN) __ R5, 2.7 k (RED-VIO-RED) __ R78, 22 (RED-RED-BLK) __ R6, 100 (BRN-BLK-BRN) __ R7, 68 (BLU-GRY-BLK) __ R8, 100 (BRN-BLK-BRN)

__ R92, 33 (ORG-ORG-BLK) __ R91, 820 (GRY-RED-BRN) __ R93, 820 (GRY-RED-BRN) __ R72, 470 (YEL-VIO-BRN) __ R95, 2.7 k (RED-VIO-RED) __ R96, 2.7 k (RED-VIO-RED) __ R74, 47 (YEL-VIO-BLK) __ R73, 2.7 k (RED-VIO-RED) __ R97, 33 (ORG-ORG-BLK)

__ R80, 680 (BLU-GRY-BRN) __ R81, 1.8 k (BRN-GRY-RED) __ R79, 1.8 k (BRN-GRY-RED) __ R82, 18 (BRN-GRY-BLK) __ R101, 10 k (BRN-BLK-ORG) __ R107,100 k (BRN-BLK-YEL) __ R111 5.6 k (GRN-BLU-RED) __ R112, 22 (RED-RED-BLK) __ R90, 470 (YEL-VIO-BRN) __ R89, 100 (BRN-BLK-BRN) __ R88, 470 (YEL-VIO-BRN) __ R84, 18 (BRN-GRY-BLK) __ R85, 150 (BRN-GRN-BRN) __ R83, 4.7 ohms (YEL-VIO-GLD)

Remove the side panels by taking out the two screws along the bottom edge of each panel.

Install the following 1/4-watt resistors, orienting them so that the first band is at the left or toward the back of the board. The resistors are listed in the order they appear on the RF board, starting with R9 (near the left edge, about halfway back).

Note: Remember to complete each line of resistors before proceeding to the next line (i.e., install R9, then R16, then R10).

Install the resistor networks. Start with RP2, which is in the front left-hand corner. Align the pin 1 mark on each resistor network with the pin 1 end of its component outline.

__ RP2, 10 k, 8 pins (8A3.103G) __ RP3, 10 k, 8 pins (8A3.103G) __ RP6, 100 k, 8 pins (8A3.104G) __ RP4, 100 k, 6 pins (6A3.104G) __ RP5, 100 k, 6 pins (6A3.104G)

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48 ELECRAFT

Locate all of the small glass-bodied diodes. You should have a number of 1N4148 diodes, and one 1N5711, which will be similar in size but should have different markings. Use a piece of masking tape to identify the 1N5711 as "D9, 1N5711."

Install the following diodes, located near the outline for toroidal transformer T5, in the synthesizer area. Be sure to orient the diodes according to their outlines.

__ D11, 1N4148 __ D13, 1N4148 __ D6, 1N4007 __ D7, 1N4007

Varactor diodes have a small plastic package, like a TO-92 transistor, but with only two leads. Sort the varactor diodes into groups: type MV209 and type 1SV149. (1SV149 diodes are labeled "V149" and may have a center lead that has been cut flush with the body of the device.) The K2 will not function correctly if the

varactor diode types are interchanged.

Install the MV209 diodes listed below. The flat side of each diode must match the flat side of its PC board outline. These diodes must be pushed all the way down on the board to prevent stray signal coupling. Bend the leads slightly to hold them in place. D16 and D23-D26 are in the front-left corner. D39 is to the right of J7 (Control board).

Install the remaining 1SV149 diodes listed below, keeping them flat against the PC board, with no excess lead length. D17, D21 and D22 are in the front-left corner. D29 through D34 are on the right side near the crystal filter.

__ D17 __ D21 __ D22 __ D29 __ D30 __ D31 __ D32 __ D33 __ D34

Install the TO-92 package transistors listed below. Start with Q17, near the middle-left edge.

__ Q17, 2N7000 __ Q16, PN2222A __ Q18, J310 __ Q19, J310 __ Q20, 2N7000 __ Q24, J310 __ Q25, PN2222A

Install Q21 (2N5109), which is located near U1 in the middle of the board. Align the small tab on the transistor’s case with the tab on its component outline. Bend the leads on the bottom to hold Q21 in place, then solder.

Install Q22 (2N5109), which is to the right of the "ELECRAFT" label. Make sure Q22 is flat against the board before soldering.

__ D16 __ D23 __ D24 __ D25 __ D26 __ D39

Note: Do not install D19 and D20. These are supplied with the planned K60XV option, which should not be installed until the K2 has been aligned and tested.

Install type 1SV149 diodes at D37 and D38, near the SSB option connector. Keep them flat against the PC board, with no excess lead length.

Carefully press a 3/4" (19 mm) dia. by 0.25" (6.4 mm) high star heat sink onto Q22. The heat sink should be pressed down as far as it will go, and should not touch the components around the transistor. The heat sink is fragile. If you need to spread it

slightly, use a blunted wooden pencil or a plastic wire nut.

Install Q12 (2N7000), which is to the right of Q22.

Install Q23 (2N7000), near the right-front edge of the board.

Install C167 (.001 µF, "102"), which is near J11, the connector for the SSB adapter. The leads on this capacitor should be formed to match its PC board outline.

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ELECRAFT 49

Sort all of the remaining capacitors by value to reduce the possibility of assembly errors in the next step. If you are unsure of any capacitor’s value and do not have a capacitance meter, the pictures in the parts list (Appendix A) may help.

Install the following capacitors, starting with C86 in the front-

left corner. Integer values are in pF and fractional values are in µF.

__ C86, 0.1 (104) ⇒ __ C84, 120 (121) ⇒ __ C85, 120 (121) __ C100, .001 (102) __ C95, .01 (103) __ C96, 1 µF (105) __ C71, 82 (82) __ C72, 270 (271) __ C73, 47 (47) __ C74, 20 (20)

__ C82, .001 (102) __ C80, .001 (102) __ C81, .001 (102) __ C79, .001 (102) __ C59, 0.1 (104) __ C38, .001 (102) __ C55, .01 (103) __ C61, .01 (103) __ C58, .01 (103) __ C65, 0.1 (104) __ C54, .01 (103)

__ C68, 10 pF (10) __ C64, .001 (102) __ C67, 0.1 (104) __ C63, .01 (103) __ C92, .022 (223) __ C94, 0.047 (473) __ C89, .001 (102) __ C87, .01 (103) __ C175, .01 (103) __ C62, .01 (103) __ C154, 100 (101) __ C144, 100 (101)

__ C156, .047 (473) __ C158, .01 (103) __ C53, .01 (103) __ C52, .01 (103) __ C141, .01 (103) __ C57, .001 (102) __ C146, .01 (103) __ C151, 0.1 (104) __ C145, .01 (103) __ C153, 68 (68) __ C155, .01 (103) __ C172, .01 (103)

__ C177, .022 (223) __ C174, 82 (82) __ C173, 220 (221) __ C178, 0.1 (104) __ C176, 0.1 (104) __ C165, .01 (103) __ C169, 390 (391) __ C168, .01 (103) __ C160, .01 (103) __ C159, .01 (103) __ C143, .01 (103) __ C142, .01 (103)

__ C163, .01 (103) __ C162, .047 (473) __ C164, .01 (103) __ C170, .047 (473) __ C166, .047 (473) __ C179, 100 (101) __ C182, 180 (181) __ C184, .01 (103) __ C185, 0.1 (104) __ C181, .01 (103)

Install the following ICs, aligning the notched end of each IC

with the notch on its component outline. U6 is at the front-left.

__ U6, LMC662 ⇒ __ U5, LTC1451 ⇒ __ U4, MC145170 __ U3, LT1252 __ U10, NE602 __ U9, LT1252 __ U11, NE602 __ U12, MC1350

Install U8 (78L05), which has a plastic TO-92 package like a

transistor. U8 is located near the front left corner of the board.

Option-bypass jumpers W5, W2 and W3 are located on the right side of the board, near the crystal filter. Use component leads to make these jumpers, or remove the insulation from appropriate lengths of green hookup wire. These jumpers should be formed so that they lie flat on the board, and should not touch any adjacent components.

Test points TP1, TP2, and TP3 are round, yellow, single-pin female connectors. TP1 and TP3 can be found in the synthesizer area of the board. TP2 is near the SSB option connector, J11. Install and solder all three test points.

Install RF choke RFC13 (100 µH, BRN-BLK-BRN), near the middle of the board. Orient the first color band to the left.

Install the receive mixer, Z6 (TUF-1), below the "ELECRAFT" label at the middle of the board. Make sure that Z6 is lined up with its component outline and is flush with the board before soldering.

Install the electrolytic capacitors in the order listed below, starting with C60 near the far left-hand edge. Insert the (+) lead of each capacitor into the hole with the (+) symbol.

__ C60, 100 µF __ C93, 10 µF __ C103, 220 µF

Install RFC15 (100 µH subminiature RF choke) and C91 (.001 µF) as explained in the manual errata sheet.

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50 ELECRAFT

Locate the crystals used on the RF board: 12.096 MHz (1),

4.9152 MHz for BFO (2) and 4.9136 MHz for crystal filters (7).

Do not mix the BFO and filter crystals, which have different characteristics.

The bag of 7 filter crystals should have a number written on it. Record the number here: ___________. (This identifies the tested frequency of the crystals, and can be used in aligning filters.)

Install the 12.096 MHz crystal, X1, at the lower left. The crystal should be seated flat on the board before soldering (it is OK to bend the pins to hold it to the board). X2 is not used.

To the left of X1 (along the edge of the board) you’ll find a pad for grounding the crystal case. Use short lengths of bare wire to ground the crystal on at the top of the can.

Install the BFO crystals at X3 and X4 (near J7). Important: trim X3's leads, and fold them down flat against their pads, before

soldering. Then use a minimal amount of solder. This is necessary to

avoid interference between X3 and L33 in a later step.

Ground the cases of X3 and X4. The ground pads are to the left of the crystals.

Install the 4.9136 MHz filter crystals at X5 through X11.

In the following steps you’ll install several toroidal inductors. Use the number of turns indicated. Do not attempt to alter the turns to match inductances specified in the parts list.

Sort the black and dark gray toroidal cores into three groups to avoid mis-identifying them in later steps. You should have eight FT37-43 ferrite cores (3/8", 9.5 mm); four T44-10 iron powder cores (0.44", 11 mm); and one FT50-43 ferrite core (0.5", 12.7 mm). Ferrite cores are dark gray; T44-10 cores are black.

Locate a 3/8" (9.5 mm) diameter ferrite toroidal core (type FT37-43) as described above.

Find RFC14’s component outline on the RF board, near the front left-hand corner. Compare this component outline to Figure 6-15, which shows two views of a typical toroidal inductor. RFC14 will be mounted vertically as shown at the right side of the drawing, with one wire exiting at the core’s upper left, and the other at the lower right. There are pads on the PC board in these two locations.

Ground the cases of X5 and X6. The ground pads are near

where the two crystals meet.

A special grounding technique is required for X7-X11.

There are two ground pads for each of these crystals, one on either side. Use bare wires (10 total) for grounding the crystals as you did in previous steps, but do not solder the wires to the tops of the crystals. The wires must be soldered to the sides of the crystals, instead, about 1/4" (6 mm) up from the surface of the PC board.

Be very careful not to overheat the crystals. Use a temperature-controlled iron, and limit soldering time to about 3 seconds per soldering attempt.

Remove insulation

Figure 6-15

Note: Toroid illustrations such as the one above do not always show the actual number of turns used.

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ELECRAFT 51

To wind RFC14, cut a 9" (23 cm) length of #26 red enamelcoated wire, then "sew" the long end of the wire through the core exactly 10 times. Each pass through the core counts as one turn. The finished winding should look very similar to Figure 6-15, but with 10 turns rather than 14.

Verify that the turns of RFC14 are not bunched together. They should be evenly-spaced and occupy about 85% of the core’s circumference. If the turns are all bunched together, RFC14’s inductance value will not be correct. (Unless otherwise specified, about 80 to 90% of the core should always be used.)

Stripping Toroid Leads

The enamel wire supplied with the kit can be heat-stripped. One way to do this is to place a small amount of solder (a "blob") on the end of your soldering iron, then insert the wire into the hot solder for a few seconds. Another possibility is to burn the insulation off by heating it with a match or small butane lighter for a few seconds, then use fine-grain sandpaper to remove the enamel residue. Avoid scraping insulation off with a razor blade, as this may nick the wire.

Strip and tin the leads of the toroid before you mount it on the board. As shown in Figure 6-15, you should remove the enamel from the leads up to about 1/8" (3 mm) from the core. You should see only bare wire (no insulation) on the side to be soldered.

Do not use adhesives or fixatives of any kind to

secure toroids to the PC board. Toroids will be adequately held

to the board by their leads alone. (T5 is the only exception.)

RFC16 is wound on an FT37-43 core (dark gray) using 16 turns of red enamel wire (12", 30 cm). Wind this inductor in the same manner as RFC14. Install RFC16 vertically, to the right of RFC14.

RFC11 is wound on an FT37-43 core using 20 turns of red enamel wire (16", 40 cm). Wind this inductor and prepare its leads in the same manner as RFC14.

Install RFC11 horizontally, on the bottom side of the board, as shown by its component outline (near the center of the board). The pads for RFC11 are the two that just touch the outline. Pull the leads taut on the top to keep the toroid secured to the board, then solder.

T5 is a toroidal transformer, with two numbered windings. These numbers are printed next to each pad on the PC board. T5’s windings are 1–2 and 3–4

Locate the large yellow core (T50-6) for use at T5. The core

is 1/2" (12.7 mm) in diameter.

Install RFC14 vertically as shown by its component outline, near the front left-hand corner of the board, then pull the leads taut on the bottom of the board.

Solder the leads of RFC14. When soldering, make sure that the solder binds well to the leads. If the lead appears to be an "island" in a small pool of solder, chances are it is not making good contact. Measure from pad to pad (not wire to wire) using an ohmmeter to be sure the leads are making contact.

Wind the first winding, 1-2, using 16 turns of red enamel wire

(15", 38 cm). This winding must occupy 85% of the core, and will look very similar to Figure 6-15. Remember that each pass through the core counts as one turn.

Carefully strip and tin the leads of T5’s 1-2 winding.

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52 ELECRAFT

T5’s other winding, 3–4, uses 4 turns of green enamel wire (7", 18 cm). Wind the 3–4 winding on top of the 1–2 winding, interleaving the turns as shown in Figure 6-16. The turns should be

secure, not loose. Strip and tin the leads of the 3–4 winding.

Note: T5’s 3–4 winding must be wound exactly as illustrated or the VFO will not function correctly.

Green,

4 turns

Figure 6-16

Install T5 as shown by its component outline in the synthesizer area of the board. Figure 6-17 shows how the 1–2 and

3–4 windings are oriented with the numbered pads. (Also shown are the nylon washer and screw, which will be installed in the next

step.) Pull T5’s leads taut on the bottom of the board, but do not solder yet.

Figure 6-17

T7 is a toroidal transformer wound on a 3/8" (9.5 mm) diameter ferrite core (dark gray, FT37-43). T7’s orientation and windings will appear similar to Figure 6-18. Wind T7’s 3–4 winding

first, using 20 turns of red enamel wire (20", 51 cm). (The drawing shows 14 turns.)

Wind T7's 1–2 winding using 5 turns of green enamel wire (6", 15 cm). Strip and tin the leads of both windings.

Secure T5 to the board as shown in Figure 6-17 using a 3/8" (9.5 mm) diameter nylon washer, 1/2" (12.7 mm) long nylon 4-40 screw, and a #4 nylon nut. Tighten the nylon nut just enough to hold the assembly in place. Do not over-tighten as this will strip the threads. Solder T5, checking for good solder joints as before.

Figure 6-18

Install T7 as shown by its component outline near the frontright corner of the board, with the windings oriented as shown in Figure 6-18. Pull the leads taut on the bottom and solder.

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ELECRAFT 53

(

)

(

)

(

)

Transformer T6 is mounted vertically, near the middle of the board. It uses a different winding technique where the wires for the two windings are twisted together before winding ("bi-filar"). Cut two 12" (30 cm) lengths of enamel wire, one red and one green. Twist them together over their entire length. The wires should cross over each other about once every 1/2" or 12 mm.

Wind the twisted wires onto a 3/8" (9.5 mm) ferrite core (FT37-43), using exactly 10 turns. Use the same method you used when winding non-twisted wires, covering about 85% of the core. Figure 6-19 shows how the winding should look from two views (your turns count will be 10 rather than 8 as in the drawing).

(a)

GRN

RED

Clip and untwist the ends of the red/green pairs so that the leads of the transformer look like those in Figure 6-19 (b). The pin numbers shown match the component outline, with the red wires numbered 1-3 and the green wires numbered 2-4

Strip and tin all four wires. Be careful not to strip the leads so close to the core that the red/green wire pairs might short together.

Install T6 vertically, with the wires inserted as indicated in Figure 6-19 (b). Pull the leads taut on the bottom, then solder.

Sort the slug-tuned shielded inductors into two groups: 1 µH

("T1050", quantity 4) and 4.7 µH ("T1005", quantity 8).

Install 4.7 µH inductors at L30 and L34 ("T1005"). Press these inductors down as far as they’ll go before soldering.

Install the components listed below, starting with C39 in the back left corner (near the key jack).

__ C39, .001 (102) __ C4, 820 (821) __ C5, 100 (101) __ C9, .001 (102) __ C7, 100 (101)

__ C8, 820 (821) __ C108, .01 (103) __ W6 (option bypass jumper) __ D1, 1N4007 __ R38, 1 k (BRN-BLK-RED) __ D2, 1N4007

__ RFC1, 100 µH (BRN-BLK-BRN)

(b)

(GRN)

RED

Figure 6-19

__ C107, .01 (103) __ C109, .01 (103) __ C110, .01 (103) __ D3, 1N4007 __ D5, 1N4007 __ D4, 1N4007 __ R37, 100 k (BRN-BLK-YEL) __ R39, 1 k (BRN-BLK-RED)

__ C113, .01 (103) __ C114, .01 (103) __ W1 (option bypass jumper)

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54 ELECRAFT

Review Figure 4-2 before installing Q2 in the next step. Q2 is a ZVN4424A transistor, which has a slightly modified TO-92 package. It is flat on both sides, and the labeling may be on the smaller flat side. The wider flat side must be aligned with the flat side of the component outline.

Install Q2, which is near C113 (just installed). Be sure to orient Q2 as shown in Figure 4-2.

RFC3 is wound on an FT37-43 core (dark gray) using 16 turns of red enamel wire (12", 30 cm). Wind this inductor in the same manner as RFC14. Install RFC3 vertically, just to the left of W1.

Install 4.7 µH slug-tuned shielded inductors (marked "T1005") at L1 and L2, near the back-left edge of the board.

Install the 40-meter low-pass filter components, which are listed below. These components are located near Q22 (2N5109 transistor with heat sink).

__ C225, 390 (391) __ C228, 56 (56) __ C227, 330 (331) __ C226, 680 (681) __ C229, 220 (221)

__ L25, T44-2 (red), 14 turns #26 red enamel wire, 14" (35 cm) __ L26, T44-2 (red), 12 turns #26 red enamel wire, 13" (33 cm)

__ C133, 0.1 (104) (bend body down before soldering)

__ C135, .01 (103) __ C122, 56 (56) __ C119, .01 (103) __ C17, .001 (102) __ C27, .001 (102) __ C104, 68 (68) __ C29, 12 (12) __ C28, 12 (12)

__ R34, 2.7 k (RED-VIO-RED) __ RFC2, 100 µH (BRN-BLK-BRN) __ RFC7, 15 µH (BRN-GRN-BLK)

Find the "C6" label, along the back edge. The three pads near C6 are labeled "J15" on the top side (for a future option module). Install C6 (4.7 pF) into the outer two of the three pads.

Locate L31, a 10 µH shielded solenoidal inductor (black case; may not be color coded). L31 is mounted on the bottom of the board, near the right edge. When soldering L31, be careful not to damage diode D18, which is on the top side near one of L31’s leads.

Install the group of components listed below on the bottom of the board. C183 is near the front left corner.

__ C183, .01 (103) __ C186, .01 (103) __ C161, .01 (103) __ C150, 330 (331)

__ C90, .047 (473) (bend body down before soldering) __ C157, .047 (473) (bend body down before soldering)

The leads of some bottom-mounted components may need

to be pre-trimmed before mounting and soldering. See Page 11.

Install the following components on the bottom side of the board, starting with C207 at the back left. Once all components have been installed, solder them on the top side, being careful not to damage any adjacent top-mounted components.

__ C207, .001 (102) __ C216, .001 (102) __ C223, .001 (102) __ C224, .047 (473) (bend body down before soldering) __ C204, .001 (102) __ C208, .001 (102) __ C195, .001 (102)

(continued)

__ R77, 220 (RED-RED-BRN) __ R76, 10 (BRN-BLK-BLK) __ R75, 680 (BLU-GRY-BRN) __ R94, 82 (GRY-RED-BLK) __ R99, 270 (RED-VIO-BRN) __ R98, 270 (RED-VIO-BRN) __ R100, 820 (GRY-RED-BRN) __ R110, 5.6 k (GRN-BLU-RED) __ R114, 3.9k (ORG-WHT-RED) __ R18, 1 M (BRN-BLK-GRN) __ R29, 10 k (BRN-BLK-ORG)

__ R19, 2.7 k (RED-VIO-RED)

__ RFC12, 100 µH (BRN-BLK-BRN)

__ D36, 1N4007

__ RFC10, 1 mH (BRN-BLK-RED)

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ELECRAFT 55

The BFO toroid, L33, is supplied pre-wound due to

the large number of turns and very small gauge wire required. When handling L33, be very careful not to damage the leads.

Locate the rubber stem bumper. Clip off about one-half of the

tip of the stem using diagonal cutters.

L33 is located on the bottom of the board, near the front center. Place the rubber stem bumper directly on top of L33's component outline. Flush-trim the leads of all parts under or

near L33 so the stem bumper can sit flat on the PC board.

Locate the pre-wound BFO inductor, L33 (41 µH, 5%). It may be supplied in a small envelope or bag labeled "L33".

Press L33 down onto the stem bumper as far as it will go. Position L33 and the stem bumper as shown in Figure 6-20.

Locate resistor R116 (1/8th watt, 5.1 megohm, green-browngreen). Bend the leads of R116 down at 90-degree angles to match the spacing of L33's pads (Figure 6-20).

Insert R116's leads into L33's pads, then press the resistor down directly on top of L33. The resistor's body should be partially recessed into the "well" left in the center of the toroid.

R116

L33

Stem Bumper

Leads

Figure 6-20

Figure 6-21

Use the leads of R116 to hold L33 firmly to the board (Figure 6-21), bending them outward on the top side. Solder R116.

Solder L33's leads to the leads of the resistor points as shown in Figure 6-22. Keep L33's leads as short as possible, and away from any nearby component pads.

Trim off the excess portion of L33's leads. Note: Trimming fine wire may be difficult with worn or poor-quality diagonal cutters. Be careful not to stress L33's leads in the process. Use a magnifying glass if necessary.

Figure 6-22

To ensure that R116 cannot short to the bottom cover, attach a thin self-adhesive insulator to the bottom cover in the area directly beneath L33. Electrical or other types of tape may be used.

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56 ELECRAFT

(

)

Visual Inspection

Examine the bottom (solder side) of the RF board carefully for unsoldered pins, solder bridges, or cold solder joints. Since this is a large board, you should break the examination up into three parts:

__ perimeter of the board __ front half __ back half

Examine the top (component side) of the RF board for unsoldered pins, solder bridges, or cold solder joints. This step is necessary because some components are installed on the bottom of the board.

Make sure switch S1 on the RF board is in the OFF position. (Plunger OUT is OFF.)

Resistance Checks

Perform the following resistance checks:

Test Point Signal Name Res.

R115, right end (near S1

U6 pin 8 8B > 100 ohms U4 pin 16 5B > 1 k U11 pin 8 8A > 250 ohms U10 pin 8 8 T > 500 ohms U12 pin 1 8R > 500 ohms

12V IN > 500 ohms

to GND

below before attempting the alignment steps in the next section. If you don’t put the chassis together, some alignment results will not be accurate.

each.

four chassis screws.

chassis screws.

verify that all components on the bottom of the RF board have an installed height of 1/4" (6 mm) or less. Capacitors that stand above this height must be bent downward at an angle to prevent them from hitting the bottom cover.

chassis screws.

It is very important to re-assemble the chassis as described

Install the two side panels and secure with two chassis screws

Plug in the front panel assembly. Secure the front panel with

Plug in the Control board.

Secure the front panel and Control boards together using two

Before installing the bottom cover in the following step,

Install the bottom cover and secure it temporarily using six

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ELECRAFT 57

Alignment and Test, Part II

In this section you’ll test and align the PLL (phase-locked-loop) synthesizer and receiver circuits. Once this is completed you’ll be able to test the receiver using all modes on 40 meters.

Connect your power supply or battery and turn on the K2.

4 MHz Oscillator Calibration

Plug the frequency counter probe into P6 (Control board).

Connect the probe tip to the PLL reference oscillator test

point, TP3 (left-front corner of the RF board, near U4).

Using the menu, select C A L F C T R , then hold

E D I T a second time to enable the frequency counter. The counter

should show a frequency of 12090 kHz +/- 30 kHz. If it is 0000.00, changing rapidly, or out of range, you could have a problem with the counter probe or the PLL Reference Oscillator.

Use one of the following methods to adjust C22 on the

Control board (listed in order of preference):

 Connect a calibrated external frequency counter probe to TP3,

without removing the K2's internal counter probe. Adjust C22 until the K2's reading matches the external counter's reading.

 Alternatively, you can use a calibrated short-wave or ham-band

receiver. Set the receiver for LSB or USB mode. Connect a short length of wire to the receiver's antenna jack, and lay the end near the 4 MHz crystal on the K2 Control board. Find the oscillator signal on the receiver. Tune the receiver to 4.000 MHz, and adjust C22 until you hear a zero-beat (pitch = 0 Hz).

 If you don't have a counter or receiver, leave C22 set at its

mid-point for now. You can improve the calibration later using a calibrated signal generator or an on-air signal, such as WWV (at 10.000 MHz).

PLL Reference Oscillator Range Test

Set up the K2 internal counter as described for 4 MHz

Oscillator Calibration (at left, first three steps).

If you have an external frequency counter probe connected to

TP3 along with the K2's internal counter probe, disconnect it.

When you’re in frequency counter mode, the B A N D + and

B A N D - switches can be used to check the range of the PLL

reference oscillator. First, tap reading below (typically about 12100 kHz). Then tap write down this frequency reading (typically 12080-12090 kHz).

Ref. High Freq. Ref. Low Freq. Range (kHz) ____________ ____________ __________

Subtract the lower frequency reading from the higher reading. The range must be between 9.8 and 13 kHz (if not, see Troubleshooting). Tap

M E N U to exit C A L F C T R .

B A N D + and write down the frequency

B A N D - and

VCO (Voltage-Controlled Oscillator) Test

Use B A N D + or B A N D - to select the 80-meter band, and set the VFO for a frequency of about 4000.10 kHz.

Connect the frequency counter probe to the VCO test point, TP1. Activate the frequency counter using C A L F C T R as before.

You should now see a frequency counter reading in the 8 to 10 MHz range. It may or may not be stable at this time (i.e., the frequency may be changing). If the reading is 0000 kHz or is changing rapidly, you probably don’t have the counter cable connected to the VCO test point. If the reading is fairly stable but not between 8 and 10 MHz, refer to Troubleshooting.

Tap M E N U to exit C A L F C T R .

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58 ELECRAFT

VCO Alignment

In the following steps you’ll adjust the VCO inductor (L30) so that the VCO control voltage is in the proper range.

Disconnect the internal frequency counter probe and remove

it completely from the K2.

Select 80 meters, and set the VFO for about 4000 kHz.

Connect a DMM (digital multimeter) to the left end of resistor R30 (near the center of the synthesizer area of the RF board) and ground. Use a small alligator clip to ensure a good connection. (You can also use the built-in voltmeter to measure the VCO control voltage. Refer to Voltmeter Probe Assembly in Part I.)

It is possible to damage the slugs in slug-tuned inductors if you use a metal tool or if you tune the slug too far in or out. The tuning tool provided will not damage the slugs.

Using the wide end of the plastic tuning tool, adjust the slug in inductor L30 until the voltage at R30 reads 6.0 V. If the voltmeter reading does not change at all as you tune L30 through its full range, refer to Troubleshooting. If the voltage changes but you cannot get to 6.0 V, you have probably wound the VCO inductor (T5) incorrectly or have installed the wrong value at L30 or C72.

Set the VFO for approximately 3500 kHz.

Measure and write down the VCO control voltage at this frequency in Table 6-1 (using pencil).

For each remaining band, set the VFO to the low and high frequencies listed in Table 6-1 and write down the VCO control voltages. the table by selecting the 1-kHz tuning rate.)

(You can tune quickly to the approximate frequencies in

Table 6-1. VCO Voltage Readings

Band Low Freq. 80 m 3500 ______ 4000 ______

40 m 7000 ______ 7300 ______ 30 m 10000 ______ 10150 ______ 20 m 14000 ______ 15000 ______ 17 m 18000 ______ 18200 ______ 15 m 21000 ______ 21450 ______ 12 m 24800 ______ 25000 ______ 10 m 28000 ______ 28800 ______

If some VCO control voltage readings above are < 1.5 V, or some of them are > 7.5 V, you may be able to shift the entire set of readings so that they are all within the 1.5 to 7.5 V range. Switch to the band (and frequency) that had the highest or lowest voltage, then adjust L30 to bring that reading into range. Then re-measure all of the voltages to make sure they're in range.

If you have some voltages that are < 1.5 V and others that are > 7.5 V, you have probably installed the wrong value at one or more of the VCO capacitors (C71-C74) or varactor diodes (D21D26). Another possibility is that T5 has the wrong number of turns or that you installed the wrong type of slug-tuned inductor at L30. If you change any of these components, repeat the VCO alignment procedure.

Disconnect the DMM from R30.

Connect the internal frequency counter probe to the BFO test

point, TP2 (right side of the RF board, near the crystal filter).

Voltage High Freq. Voltage

Usable VFO coverage extends well beyond the ranges given in the table. 15 MHz is used as the upper boundary on 20 meters to allow reception of WWV at this frequency.

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ELECRAFT 59

BFO Test

The BFO (beat-frequency oscillator) will be tested in the following steps.

Switch to the 40-m band.

Connect the frequency counter to the BFO test point (TP2),

which is on the right side of the RF board near the crystal filter.

Using the menu, select C A L F C T R . The counter should show

a frequency between 4908 and 4918 kHz.

If you see a reading of 0 0 0 0 . 0 0 kHz or one that is

changing rapidly, you may not have the frequency counter probe connected properly, or the BFO may not be working (see Troubleshooting). If you see a stable frequency reading that is nowhere near 4908-4918 kHz, you may have installed the wrong crystals in the BFO (X3/X4).

When you’re in frequency counter mode, the B A N D + and

B A N D - switches can be used to check the range of the BFO. First,

tap

B A N D + and write down the frequency reading below (typically

about 4916-4917 kHz). Then tap frequency reading (usually about 4909-4912 kHz). Finally, calculate

the BFO range (high - low) in kHz. Typical range is 4 to 6 kHz.

B A N D - and write down this

If your BFO range is less than 3.6 kHz, you may have the wrong varactor diodes installed at D37 or D38, or the wrong crystals installed at X3 or X4.

If the BFO frequencies are shifted too high or too low, it may be due to one of the following:

 If you didn't calibrate the K2's internal frequency counter using

an external counter, it may not be reading accurately. If possible, borrow an accurate counter and re-do the 4 MHz Oscillator Calibration.

 The BFO range shift could be due to the inductance of L33

being too high or too low. However, since L33 is supplied prewound and tested, this is unlikely.

 The leads of R116 may have been heated excessively during

soldering, shorting out a portion of L33's turns.

 One of L33's leads could be broken. Look closely at the leads

using a magnifying glass.

 One or more of the capacitors or varactor diodes in the BFO

circuit could be of the wrong value.

BFO High Freq. ___________ (must be >= 4916.3 kHz)

BFO Low Freq. ___________ (must be <= 4912.7 kHz)

Range (High - Low) ___________ (must be >= 3.6 kHz)

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60 ELECRAFT

BFO Alignment

The K2 uses a variable-bandwidth crystal filter, allowing the operator to set up as many as four filter bandwidths for each operating mode. Each of these filter configurations requires an appropriate BFO setting, which determines the pitch you hear.

Filter and BFO set up is done with the C A L F I L calibration function. C A L F I L is described in detail in the Operation section of the manual, under Calibration Functions. Rather than duplicate this information here, the instructions and example in the Operation section will be used.

Make sure the bottom cover is securely attached.

Tap P R E / A T T until the PRE annunciator is turned on.

(Turning the preamp on will provide some background noise so you can hear the effect of changing filter bandwidths.)

Follow all instructions on page 85 to become familiar with the

C A L F I L function.

Perform the steps in the example on page 86 to set up all filters. You'll use the filter and BFO data from Table 8-1 (for a CW-only K2), since the SSB adapter is not installed. If you later install the SSB adapter, you can easily change the settings to take advantage of the optimized, fixed-bandwidth SSB filter.

VFO Linearization

Make sure the bottom cover is securely attached.

Allow the K2 to stabilize for at least 10 minutes at room

temperature (approx. 20-25°C). (Note: Avoid using a high-wattage work lamp direct above the K2 during calibration. With the top

cover removed, this could heat the RF board to a higher temperature than would ever be seen during normal operation.)

Connect the internal frequency counter cable to the VCO

output test point (TP1).

Use the procedure listed below to linearize the VFO. If you see

any I N F O messages, refer to Troubleshooting.

1. Use

2. Set the VFO to anywhere in the range 7000-7100 kHz.

3. Enter the menu and select C A L P L L , then hold

4. The frequency counter will show the VCO frequency as it

5. When calibration is completed (4-8 minutes), you'll see the

B A N D + or B A N D - to select 40 meters. Select CW normal

mode and filter FL1.

E D I T a

second time to start the VFO linearization sequence.

decreases through a range of about 10-13 kHz. (The letter "d " will flash each time a calibration data point is stored.)

message E n d on the LCD. You can then tap any switch to return to normal operation. If you see an INFO message rather than E n d , refer to Troubleshooting (Appendix E).

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ELECRAFT 61

I.F. Amplifier Alignment

L34, located near the right front corner of the RF board, is used to peak the output of the I.F. amplifier.

Using the wide end of the plastic tuning tool, adjust the slug in

L34 until it is near the top of the can. Stop turning the slug

when it appears to be at the top or when you feel resistance.

Turn L34’s slug one full turn clockwise (down into the can).

Set the band to 40 meters using B A N D + or B A N D - . Select CW

Normal and FL2 (700 Hz nominal bandwidth).

Make sure the RF GAIN control is fully clockwise (max. gain).

Disconnect the antenna from J4, if one was connected.

Tap P R E / A T T N until the PRE annunciator turns on.

Connect a pair of headphones (stereo or mono) to the front

panel jack, and turn the AF GAIN control to about midway.

Slowly tune the VFO to locate the weak internally-generated signal near 7000 kHz. If you can't hear the signal at all, you may have a receiver problem. Try the 40-meter Band Pass Filter Alignment, below, then refer to Troubleshooting if necessary.

Using the plastic tuning tool, adjust both L1 and L2 (back left corner) for peak signal strength. You may be able to use the bargraph if the signal is strong enough. If you do not hear any signals or noise, see Troubleshooting.

In CW mode, the frequency shown on the display takes into account an offset equal to your sidetone pitch. This allows you to determine a station's actual carrier frequency by matching their pitch to your sidetone, rather than by zero-beating the signal. The

S P O T switch can be used for this purpose.

This completes 40-meter receiver alignment. You may wish to become familiar with the K2’s receiver features before proceeding (see Operation). In Part III you’ll install the remaining band-pass filters and align the transmitter and receiver on all bands.

Assembly, Part III

In this final RF board assembly section you’ll install the transmitter components, as well as the remaining band-pass and low-pass filters. This will allow you to align and test the K2 on all bands.

Turn off the K2 and disconnect the power supply.

While listening to the signal at 7000 kHz, adjust L34 for best

signal strength and lowest noise. This setting occurs at about 1 to

1.5 turns below the top of the can. (You can use your DMM on AC volts, at the speaker jack, to obtain a more sensitive indication.)

40-Meter Band Pass Filter Alignment

Connect an antenna or a signal generator to the antenna jack on the rear panel. If you use a signal generator, set it for approx. 7150 kHz at an output level of about -100 dBm, or strong enough to activate the S-meter. If you're using an antenna, tune in a signal in the range of 7100-7200 kHz. If you cannot find a signal, you can use atmospheric noise from the antenna to peak the filter.

Remove the two screws holding the Front Panel board to the Control board, then unplug the Control board. Use the long-handled Allen wrench as described in Part I.

Remove the bottom cover.

Remove the screws from the front panel assembly and unplug it from the RF board.

Remove the side panels by taking out the two screws along the bottom edge of each panel.

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62 ELECRAFT

Install the following 1/4-watt resistors, starting with R46

which is just to the left of I/O controller U1.

__ R46, 270 (RED-VIO-BRN) ⇒ __ R45, 47 (YEL-VIO-BLK) __ R59, 4.7 k (YEL-VIO-RED) __ R61, 120 (BRN-RED-BRN) __ R49, 120 (BRN-RED-BRN) __ R40, 470 (YEL-VIO-BRN) __ R41, 560 (GRN-BLU-BRN) __ R55, 33 (ORG-ORG-BLK)

__ R53, 4.7 ohms (YEL-VIO-GLD) __ R56, 33 (ORG-ORG-BLK) __ R54, 4.7 ohms (YEL-VIO-GLD) __ R60, 100 ohms (BRN-BLK-BRN) __ R62, 2.7 k (RED-VIO-RED) __ R67, 1.5 k, 1% (BRN-GRN-BLK-BRN) __ R68, 226 ohms, 1% (RED-RED-BLU-BLK)

The 150 pF and 3.3 pF capacitors to be installed below

may be hard to identify. See capacitor information on page 9.

Install the capacitors listed below. C12 is near the back left corner. Note: C13 and C14 will not be installed; they are included with the 160 m/RX Antenna option (K160RX).

__ C12, 560 (561) ⇒ __ C11, 1800 (182) ⇒ __ C26, .001 (102) __ C16, 1800 (182) __ C15, 560 (561) __ C22, 3.3 pF (3.3) __ C20, 47 (47) __ C19, 330 (331) __ C30, 470 (471) __ C24, 47 (47) __ C25, 330 (331) __ C35, 56 (56) __ C37, .001 (102) __ C36, 470 (471) __ C33, 2.2 pF (2.2)

__ C219, 12 (12) __ C138, .047 (473) __ C222, 100 (101) __ C221, 39 (39) __ C220, 220 (221) __ C214, 68 (68) __ C213, 33 (33) __ C212, 150 (151) __ C203, 47 (47) __ C199, 220 (221) __ C200, 150 (151) __ C202, 120 (121) __ C201, 220 (221) __ C192, 1200 (122)

There are two types of ceramic trimmer capacitors used in the band-pass filters: 30 pF and 50 pF. These may look identical. They will either be bagged separately, or the 50-pF trimmers will have a red marking.

Install the trimmers listed below, starting with C21 near the back-left corner. Orient the flat side of each trimmer capacitor with the flat side of its component outline. This orientation is required to prevent RF pickup during alignment.

__ C21, 50 pF __ C23, 50 pF

__ C32, 30 pF __ C34, 30 pF __ C44, 30 pF __ C46, 30 pF

Set all of the trimmer capacitors just installed to their mid-way points (see Figure 6-23). Use a small flat-blade screwdriver.

__ C49, .001 (102) __ C31, 56 (56) __ C42, 330 (331) __ C43, 33 (33) __ C48, 330 (331) __ C47, 33 (33) __ C45, 1 pF (1) __ C115, .01 (103) __ C117, .047 (473) __ C118, .01 (103) __ C116, 33 (33) __ C121, 0.01 (103) __ C120, .01 (103) __ C131, 0.1 (104)

__ C124, 0.1 (104) __ C130, 0.1 (104) __ C128, 680 (681) __ C129, .01 (103) __ C127, 680 (681) __ C191, 1800 (182) __ C190, 1200 (122) __ C197, 100 (101) __ C198, 27 (27) __ C210, 82 (82) __ C211, 10 (10) __ C218, 150 (151)

Figure 6-23

Install L5, a 33 µH RF choke (ORG-ORG-BLK), near the back-left corner.

Install the following transistors, which are located near the I/O Controller (U1).

__ Q10, 2N7000 __ Q11, PN2222A __ Q13, PN2222A

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ELECRAFT 63

Ferrite-bead assemblies Z1 and Z2 will be installed vertically near transformer T3 as indicated by their component outlines. To make these assemblies, string two ferrite beads onto a 1" (25 mm) length of bare hookup wire (or discarded component leads) as shown in Figure 6-24.

Figure 6-24

Install Z1 and Z2, bending the leads on the bottom of the board to hold them in place. Make sure that the beads are seated flat against the PC board, then solder.

Locate D9, the 1N5711 diode which you identified and set aside earlier. Install D9 near the right edge of the board.

Install electrolytic capacitors C126 (47 µF) and C137 (100 µF), Near the "ELECRAFT" label at the center of the board. Insert the (+) lead of each capacitor into the hole marked (+).

Install electrolytic capacitor C125 (22 µF) which is near U1.

Install Q5 (2N5109). Be sure Q5 is firmly seated on the board and has its tab oriented as shown by the component outline before soldering.

Install the following components on the bottom of the board,

working from left to right.

__ R63, 220 (RED-RED-BRN)

Note: bend the leads of R58 exactly as shown by its component outline.

__ R58, 180 ohms, 1/2 watt (BRN-GRY-BRN)

__ RFC8, __ RFC9, __ RFC4, 10 µH (BRN-BLK-BLK)

__ RFC6, 0.68 µH (BLU-GRY-SILVER) __ RFC5, 10 µH (BRN-BLK-BLK)

__ R50, 1.5 ohms, 1/2-watt (BRN-GRN-GLD)

__ R48, 120 (BRN-RED-BRN) __ R47, 47 (YEL-VIO-BLK) __ R43, 22 (RED-RED-BLK)

__ R42, 4.7 ohms (YEL-VIO-GLD) __ R44, 2.7 k (RED-VIO-RED)

Make sure you have separated the remaining slug-tuned shielded inductors into 1 µH and 4.7 µH types. Install these inductors in the order indicated below, on the top of the board. These inductors are difficult to remove once soldered, so doublecheck the part numbers. The 4.7 µH inductors are labeled "T1005," and the 1 µH inductors are labeled "T1050."

__ L3, 4.7 µH ("T1005") __ L4, 4.7 µH __ L8, 4.7 µH __ L9, 4.7 µH

__ L10, 1 µH ("T1050") __ L11, 1 µH __ L12, 1 µH __ L13, 1 µH

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64 ELECRAFT

TO-220 package transistors Q6, 7, and 8 look identical, but Q6 is different. Locate the two 2SC1969’s (labeled "C1969"), Q7 and Q8, and set them to one side. The 2SC2166 transistor, Q6 ("C2166"), will be installed first.

the component outline for Q6. The hole in the thermal pad must be aligned precisely with Q6's mounting hole on the board.

on the Control board (Figure 4-4, page 16), using gradual bends to avoid lead breakage. Insert Q6 as shown by its component outline.

lock washer and 4-40 nut. The screw should be inserted from the bottom side of the RF board; the washer and nut go on the top.

adjacent components, then solder.

below, starting at the back-right with L16 and L17 (80 meters). Wind each of the toroids using the core type and number of turns indicated (use red enamel wire). Review the toroid winding instructions and illustrations for RFC14 (Page 50).

__ L16 T44-2 (red), 21 turns 19" (48 cm) __ L17 T44-2 (red), 21 turns 19" (48 cm) __ L18 T44-2 (red), 9 turns 10" (25 cm) __ L19 T44-2 (red), 8 turns 9" (23 cm) __ L20 T44-2 (red), 7 turns 8" (18 cm)

Note: The black cores below are all of the powdered-iron (ceramic) type, not ferrite. If necessary you can identify them by measuring their diameter, which is 0.44" (11 mm), not 3/8" (9.5 mm).

Attach a self-adhesive thermal pad to the PC board on top of

Prepare the leads of Q6 as you did with the voltage regulators

Secure Q6 to the board using a 4-40 x 3/8" (9.5 mm) screw, #4

Verify that the body of Q6 is not touching the leads of any

Wind and install each of the low-pass filter inductors listed

It is very important to wind and install toroidal transformers T1 through T4 exactly as described in the following steps. Remember that transformer windings are identified by numbered pairs of leads, which correspond to the PC board and schematic.

T1 is wound on an FT37-43 ferrite core (dark gray) and has

windings similar to those shown in Figure 6-25. The 1–2 winding is 9 turns of red enamel wire (10", 25 cm). The 3–4 winding is 3 turns of green enamel wire (5", 13 cm). (The drawing shows more than 9

turns on the larger winding.)

Prepare T1’s leads as in Part II. Completely remove the insulation to within about 1/8" (3 mm) of the core, then tin the leads.

Figure 6-25

Install T1 horizontally near Q5, inserting the leads into the

matching numbered holes as indicated by the above illustration and by the component outline.

__ L21 T44-10 (black), 9 turns 10" (25 cm) __ L22 T44-10 (black), 8 turns 9" (23 cm) __ L23 T44-10 (black), 11 turns 11" (28 cm) __ L24 T44-10 (black), 10 turns 10" (25 cm)

Page 66

ELECRAFT 65

(

)

(

)

T2 is wound on the same core type as T1 (FT37-43). Its

windings must be spaced as shown in Figure 6-26(a), with the 3-4 winding occupying about half the diameter of the core. T2’s 1–2 winding is 12 turns of red enamel wire (13", 33 cm), and its 3–4 winding is 8 turns of green (9", 23 cm).

Prepare T2’s leads, but leave an extra 1/2" of insulation on

leads 3 and 4 (green) as shown in Figure 6-26(a).

Fold the leads of T2's green winding (3-4) down and under the

core as shown in Figure 6-26(b).

Install T2 horizontally, just to the right of Q6. To ensure that the leads do not contact any adjacent pads or components, T2 should be mounted so that it is elevated slightly above the board (about 1/16" [1.5 mm]).

(a)

(b)

Wind the twisted wires onto a 1/2" (12.7 mm) dia. ferrite core (FT50-43), using exactly 5 turns and covering about 85% of the core. Figure 6-27 shows how the winding should look. The leads of T3 are labeled with letters A through D on the PC board to avoid confusing them with the numbered leads of T2 and T4.

Separate T3’s leads as shown in Figure 6-27. Strip and tin the leads, being careful not to let the red/green wire pairs short together.

Install T3 vertically as shown by its component outline. T3 must be seated flat against the PC board, with its leads pulled tight on the bottom side.

(GRN)

(RED)

GRN

RED

Figure 6-26

Transformer T3 is mounted vertically, to the right of T2. The wires for the two windings must be twisted together before winding (bi-filar). First, cut two 10" (25 cm) lengths of enamel wire, one red, and one green. Then twist the wires together over their entire length. The wires should cross each other once every 1/2" or 1 cm.

Figure 6-27

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66 ELECRAFT

Locate the "binocular" (2-hole) ferrite core for T4. Wind 2 turns of green-insulated hookup wire (5", 13 cm) through the core as shown in Figure 6-28. This forms the 1–2 winding. (Do not

use enamel-coated wire.)

Cut and strip the two leads using the lengths shown. Be careful not to nick the wire.

1/2” (13mm)

7/8” (22mm)

Figure 6-28

Wind a 3-turn winding (3–4) on top of the 1-2 winding, but with the wire starting and ending on the opposite side (Figure 6-29).

Use 7" (18 cm) of white-insulated hookup wire (not enamel- coated wire). Prepare the leads in the same manner as above.

Before installing T4, verify that the screws holding the 2-D fastener beneath it are tightened, and that #4 internal-tooth lock washers were used. It is important that these screws not come loose sometime after T4 has been installed.

Install T4 to the right of T3, inserting leads for the 1–2 and 3–4 windings into their matching numbered holes. T4 should rest directly on top of the screws that secure the 2-D fastener beneath

it. T4 should also be parallel to the board, not tilted to one side. Pull the leads taut on the bottom and bend them to hold the transformer in place. Do not solder T4 yet.

Use two 2" (5 cm) lengths of bare hookup wire to form the 5–6 and 7–8

accurately described as links, each being just a single turn.) Route the bare wires through the core first, then bend them down and insert them into their numbered holes. Do not solder yet.

windings on T4 (Figure 6-30). (These are more

Figure 6-29

Figure 6-30

Adjust all of the windings of T4 as needed so that the transformer is positioned directly above its component outline. Pull the leads tight on the bottom, then solder.

Inspect all four transformers in the transmitter area closely, on both top and bottom, for shorts or cold solder joints.

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ELECRAFT 67

Place Q7 on the bottom of the board so that the leads are

inserted into the PC board as indicated by Q7’s component outline.

PA transistors Q7 and Q8 (2SC1969) must be installed on the bottom of the PC board, with their metal tabs facing away from the board, as explained in the following steps. Locate the component outlines on the bottom of the board before proceeding.

Prepare the leads of Q7 as shown in Figure 6-31. Bend the leads upward, away from the tab--the opposite of the way you bent the leads of Q6. Form the leads using the shaft of a small screwdriver to create gradual bends. Do not install Q7 yet.

Figure 6-31

Insert a 4-40 x 1/2" (12.7 mm) screw through the PC board hole for Q7’s tab (see Figure 6-31). Then slip the hardware listed below onto this mounting screw from the bottom side. (The shoulder washer can be found with the MISCELLANEOUS components.)

The mounting screw and hardware should appear as shown in Figure 6-31. Do not solder yet.

Make sure the smaller part of the shoulder washer is visible

through the hole in Q7’s metal tab.

Secure Q7 and its hardware temporarily using a 4-40 nut and

#4 lock washer. Tighten the nut only finger-tight.

Once Q7 and its hardware appears to be parallel to the PC

board as shown in Figure 6-31, solder Q7 on the top of the board.

Repeat the steps above for the other PA transistor, Q8.

Uninstalled Components

Check off the components in the list below, verifying that they are not yet installed. All of these components are on the top side of the board. Note: Most of these components are provided with option kits, as indicated in the list. Some of the connectors can be pre-installed, as will be explained on the next page.

__ J14 (near antenna jack); supplied with K160RX __ C13 and __ C14 (in 160 m band-pass filter); supplied with K160RX __ C75 (synthesizer area); supplied with K160RX

__ J15 (3-pin connector in 40 m band-pass filter); supplied with K60XV __ J13 (transverter conn., near 40 m band-pass filter); supplied with K60XV __ D19 and D20 (synthesizer area); supplied with K60XV

__ #4 fibre washer (black) __ 1/4" (6.4 mm) dia., 1/8" (3 mm) long phenolic standoff (brown) __ #4 nylon shoulder washer (black)

Do not use any hardware other than that supplied. The height of the PA transistor assembly is critical for maintaining good heat dissipation.

__ P6 (near DC input jack); supplied with KAT2 or KPA100 __ P3 (near crystal filter); supplied with KBT2 or KPA100

__ J9, __ J10, and J11 (near crystal filter); supplied with KSB2

__ J12 (near crystal filter); supplied with KNB2

__ J5 (near BFO crystals); reserved for future use

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68 ELECRAFT

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If you have already purchased option kits, you may install selected option components now, as explained in the following steps. This will simplify installation of the options after K2 alignment and test have been completed.

Do not remove the option bypass jumpers (W1, W2, etc.). The K2 must be aligned and tested before the jumpers are removed and option modules installed.

If you have the K60XV (60 meter) option, follow the instructions in the K60XV manual under "Pre-Installation During K2 Assembly".

If you have the KNB2 (Noise Blanker) option, locate the Installation section of the KNB2 manual. Complete only the installation of J12 and the standoff. Do not remove W5, R88,

R89 or R90 at this time.

K160RX Component Installation (optional)

Locate the Installation section of the K160RX kit manual.

Cross out the first three steps (turning off the K2, removing hardware, etc.), which are not applicable since the K2 is already disassembled. Skip the next two steps. Do not remove W1.

Complete the steps for J14 through C13 and C14.

Cross out the next two steps (examination of Q7 and Q8). The remaining steps should be completed after alignment.

KSB2 Component Installation (optional)

Locate KSB2 Module Installation in the KSB2 manual.

Complete only the steps required to install J11, J9, and J10, and the standoff. Do not remove W2, W3, or C167 at this

time. Complete the remaining steps after alignment.

Other Option Component Installation (optional)

If you have the KAT2 (ATU) or KPA100 (Amplifier) option, install 2-pin connector P6. Use the option manual's instructions.

If you have the KBT2 (Battery) or KPA100 option, install 2-pin connector P3. Use the option manual's instructions.

Visual Inspection

__ perimeter area __ front half __ back half

Examine the top (component side) of the RF board for unsoldered pins, solder bridges, or cold solder joints. This step is necessary because some components are installed on the bottom of the board and soldered on top.

Make sure switch S1 on the RF board is in the OFF position. (Plunger OUT is OFF.)

Resistance Checks

Perform the following resistance checks.

Test Point Signal Name Res.

Q7 collector 12V > 500 ohms

Q6 base Driver bias 100-140 ohms

Q7 base PA bias 2.5 - 3.0 k U11 pin 8 8A > 250 ohms U10 pin 8 8 T > 500 ohms U12 pin 1 8R > 500 ohms

to GND

Page 70

ELECRAFT 69

Install the two side panels and secure with two chassis screws

each as you did in Part I and Part II.

Plug in the front panel assembly and make sure the connectors are completely mated. Secure the front panel with four chassis screws.

Verify that all components on the bottom of the RF board have an installed height of 1/4" (6 mm) or less. Capacitors that stand above this height must be bent downward so that they won’t hit the bottom cover or heat sink.

Install the bottom cover and secure it using six chassis screws.

In the next step you'll install thermal insulation pads on the power amplifier transistors, Q7 and Q8. These pads must be positioned correctly to keep the collectors of the transistors from shorting to ground. Proper positioning is also required to guarantee good heat conduction.

Place self-adhesive thermal pads on top of Q7 and Q8 as shown in Figure 6-32, with the hole in the pad centered over the hole in the transistor tab. The adhesive side must be in contact with

the transistor.

Plug in the Control board. Make sure that all three connectors

are completely mated.

Secure the front panel and Control boards together using two

chassis screws.

Locate the heat sink panel. Remove any masking tape,

including the large piece that covers several holes.

Attach two round rubber feet to the heat sink using 4-40 x 7/16" (11 mm) screws, #4 lock washers, and 4-40 nuts. The screws are standard steel/zinc-plated, not black anodized. The nuts go on the inside surface of the heatsink. (The rubber feet can be found with the MISCELLANEOUS items.)

Remove the finishing nuts and washers from the shafts of the antenna and key jacks. They will be re-installed later.

Turn the K2 up on its left side. This will keep the PA transistor screws from slipping out during the following steps.

Remove the 4-40 nuts and #4 lock washers from the mounting screws for Q7 and Q8, but do not pull the screws out. (If you pull these screws out, the associated hardware will fall off and will have to be re-installed.)

4-40 screw

Thermal

Pad

Figure 6-32

Back out the mounting screws for Q7 and Q8 until the ends of the screws protrude only slightly from the transistor tabs. Keep the K2 on its left side so the screws don’t slip out further.

Make sure that the thermal pads on Q7 and Q8 are centered, and that you can see the shoulder washers inside the tab holes. If the shoulder washers have come out of the tab holes, re-align the PA transistor hardware as needed.

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70 ELECRAFT

Keeping the K2 on its left side, slip the heat sink over the rear-panel connectors and into position (Figure 6-33). Figure 6-34 shows how the heat sink and associated hardware appear in crosssection.

Heat Sink

Figure 6-33

Secure Q7 and Q8 on the bottom of the heat sink using 4-40

nuts and #4 lock washers. Do not over-tighten the nuts, as this may

cause the thermal pads to scrape against the heat sink, possibly causing a short to ground.

Figure 6-34

Using an ohmmeter on a low resistance scale, check for a short from Q7 or Q8 collector to ground. (This test should also be performed any time the heat sink is removed and re-installed.) If a short is measured, remove the heat sink and investigate the cause. The most likely reason for a short is mis-alignment of a shoulder washer or thermal pad. If a thermal pad or shoulder washer is

damaged, it must be replaced.

Make sure that the four small holes in the heat sink line up

with Q7/Q8 and the 2-D block between them.

Press the Q7/Q8 mounting screws all the way back in so that

they protrude from the heat sink.

Use two chassis screws and two #4 lock washers to secure the

heat sink firmly to the 2-D fastener.

There are four more #4 holes in the heat sink: two on the bottom and two on the back panel. Use four chassis screws to secure the heat sink to the side panels and RF board at these locations. You may need to adjust the positions of the 2-D fasteners on the side panels slightly.

Install the washers and finishing nuts that you removed earlier from the antenna and key jacks. (The antenna jack hardware is shown installed in Figure 6-34.)

Page 72

ELECRAFT 71

Alignment and Test, Part III

In this section you’ll complete alignment and test of the K2 on all bands.

Make sure the power switch, S1, is in the OFF position (out).

Connect your power supply or battery. For transmitter tests, a battery or well-regulated power supply that can handle at least 2 amps is recommended. Avoid using a switching power supply unless it is well shielded and includes EMI filtering. A linear-mode supply will typically generate much less noise in the HF bands. (See any recent ARRL Handbook for examples of both types.)

Connect a 50-ohm dummy load to the antenna jack. The dummy load should be rated at 10 watts or higher.

Connect a pair of headphones and a key or keyer paddle.

Set the POWER control fully counter-clockwise (minimum power output).

Turn on the K2. You should see E L E C R A F T on the LCD, followed by the frequency display.

Select voltage/current display mode by tapping D I S P L A Y to

make sure the receiver is not drawing excess current. (Typical current drain will be 180-250 mA depending on menu settings.)

Return to frequency display mode.

Switch to CW and select FL1 using X F I L .

Use the menu to set up the desired CW sidetone volume and

pitch if you have not already done so, using S T L and S T P . The pitch can be set from 400 to 800 Hz, although 500-600 Hz is recommended. The sidetone volume and tone will vary a small amount as the pitch is changed, but it should have a pleasant sinewave sound at any setting.

Set up the desired keying device using I N P . If you’re using a hand key or external keyer, use I N P H A N D . To use the internal keyer, select P D L n or P D L r (normal or reverse paddle). You can also connect a computer or external keyer along with the keyer paddle. Refer to the Operation section for details on this "autodetect" feature (Page 92).

To verify that the sidetone is functioning, hold the

S P O T switch. Tap any switch to turn the SPOT tone off.

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72 ELECRAFT

40-Meter Transmitter Alignment

To align the transmitter you’ll need some means for monitoring power output as you adjust the band-pass filters. An analog wattmeter or oscilloscope is ideal. However, in the instructions that follow we’ll assume that you’re using the K2’s built-in digital wattmeter, which will also provide satisfactory results.

Set the POWER control for 2.0 watts.

Switch to the 40 meter band and set the VFO for about 7100

kHz.

Locate the 40-meter band-pass filter inductors, L1 and L2, and

be prepared to adjust them using the wide end of the tuning tool.

In the following steps you’ll place the K2 into "TUNE" mode by holding 5 or 10 seconds during tune-up for safety reasons. If you see or smell smoke turn the K2 off and refer to Troubleshooting.

Note: While in tune mode, it is normal to see power drift upward several tenths of a watt. You may also see a sudden jump in power during alignment. The output will quickly be reduced to about 2.0 W by the firmware if this happens.

Put the K2 into tune mode and activate the built-in wattmeter by holding output. Tap any switch to exit TUNE mode.

T U N E . You should limit key-down periods to about

T U N E . Using the alignment tool, adjust L1 for maximum

If necessary, repeat the adjustment of L1 and L2 two or three times to be sure that you have the inductors peaked correctly. If you cannot get power output to 2.0 watts or higher, see Troubleshooting.

Make sure the bar graph is set for D O T mode using the G R P H menu entry.

Set power output to 5.0 W using the POWER control.

Tap D I S P L A Y to enter voltage/current display mode. When this display is selected, you can use

T U N E to check your voltage and

current in transmit mode.

Enter tune mode and note the change in voltage and current. Current drain at 5 watts is typically 1.3 to 1.6 amps.

If the current reading is much higher than this, or if the voltage drops more than 1 V, you may have a problem in the transmitter, load, or power supply (see Troubleshooting).

Return to frequency display using the D I S P L A Y switch.

Set the POWER control for 10.0 watts.

Enter tune mode just long enough to verify that the wattmeter reads approximately 10 watts. If you then switch to voltage/current display and hold

T U N E again, you should see a current drain of

typically 1.8 to 2 amps. If you see a "HI CUR" warning message (high current), use CAL CUR to set your transmit current limit higher. If current is much higher than 2 A, see Troubleshooting.

This completes transmitter alignment and test on 40 meters.

Enter tune mode again and adjust L2 for maximum output.

Tap any switch to exit.

The K2 transmitter is most efficient at 10 watts and higher; current drain at 5 watts CW may be higher than expected. This is unavoidable because the K2 is capable of up to 15 W output. Also, for a given power level, SSB transmission requires more transmitter "overhead" to prevent distortion.

Page 74

ELECRAFT 73

Receiver Pre-Alignment

Since the same filters are used on both receive and transmit, it is possible to align all the remaining bands on transmit only. However, you can pre-align the filters on receive by using a signal or noise generator, separate ham transceiver, or on-air signals and atmospheric noise. This pre-alignment on receive will make transmitter alignment easier, since the filter adjustments will already be at or close to their final values.

Switch to 80 meters and set the VFO for about 3750 kHz

(mid-band). Turn on the RF preamp by tapping you see the PRE annunciator turn on.

Use a signal generator or an antenna to inject a signal or noise

at this frequency.

Adjust L3 and L4 for maximum signal strength.

Since some inductors are shared between two bands, you must always align the remaining bands in the order indicated. Always use this procedure if you re-align the filters later.

P R E / A T T N until

Switch to 20 meters (14100 kHz) and turn on the preamp. Set C21 and C23 to their mid-points. Adjust L8 and L9 for maximum signal strength. (This step pre-sets C21, C23, L8, and L9 before final adjustment in the next two steps.)

Switch to 30 meters (10100 kHz) and turn on the preamp. Adjust L8 and L9 for maximum signal strength.

Switch back to 20 meters (14100 kHz). Adjust C21 and C23 for maximum signal strength.

Switch to 15 meters (21100 kHz) and turn on the preamp. Adjust L10 and L11 for maximum signal strength.

Switch to 17 meters (18100 kHz) and turn on the preamp. Adjust C32 and C34 for maximum signal strength.

Switch to 10 meters (28200 kHz) and turn on the preamp. Adjust L12 and L13 for maximum signal strength.

Switch to 12 meters (24900 kHz) and turn on the preamp. Adjust C44 and C46 for maximum signal strength.

This completes receiver alignment.

During receiver alignment, you may have noticed that signal strength is somewhat lower in volume when you select the narrowest filter (100 Hz setting, FL4). This is because the K2's crystal filter is optimized for wider bandwidths (250-800 Hz). Despite the slightly greater attenuation, the narrower settings are very useful in reducing QRM (interference) from strong, nearby signals. (Any of the filter settings can be changed, and FL2-FL4 can even be turned OFF. See page 85 for information on customizing filter settings.)

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74 ELECRAFT

Transmitter Alignment

If you did the receiver alignment, above, you may find that little or no transmit adjustment is required on most bands.

Set the POWER control for 2.0 watts.

Switch to 80 meters and set the VFO for about 3750 kHz

(mid-band).

Enter tune mode and adjust L3 and L4 for maximum power as indicated on the internal wattmeter. (Use a more sensitive analog instrument if available.) Limit tune-up time to 5 or 10 seconds.

must always align the remaining bands in the order indicated. Always use this procedure if you re-align the filters later.

mid-points. Adjust L8 and L9 for maximum power output. (This step pre-sets C21, C23, L8, and L9 before final adjustment in the next two steps.)

maximum power output.

Since some inductors are shared between two bands, you

Switch to 20 meters (14100 kHz). Set C21 and C23 to their

Switch to 30 meters (10100 kHz) and adjust L8 and L9 for

Switch to 20 meters (14100 kHz) and adjust C21 and C23 for

Switch to 15 meters (21100 kHz) and adjust L10 and L11 for

Switch to 17 meters (18100 kHz) and adjust C32 and C34 for

Switch to 10 meters (28200 kHz) and adjust L12 and L13 for

maximum power output.

Switch to 12 meters (24900 kHz) and adjust C44 and C46 for

maximum power output.

This completes transmitter alignment.

Page 76

ELECRAFT 75

7. Final Assembly

Place the top cover upside down as shown in Figure 7-1, with its rear panel facing away from you. The illustration shows how the speaker, 2-conductor cable, external speaker jack and other hardware will be attached to the top cover.

3/8" (9.5 mm)

Cable Ties (3)

Trim the supplied grille cloth to the size of the speaker frame.

Place #4 fibre washers (black) at each of the top cover's four speaker mounting holes (Figure 7-1). Trim the corners of the grille cloth so it just fits between the fibre washers, not touching them.

Place the speaker on top of the fibre washers and grille cloth. Secure it with four 3/8" (9.5 mm) screws, #4 lock washers, and 4-40 nuts (Figure 7-2). Do not over-tighten the nuts.

9" (23 cm)

Top Cover

Figure 7-2

15"

Locate the two holes marked A in Figure 7-1. Use two 4-40 x 3/8" (9.5 mm) screws to fill these holes, securing them with #4 lock washers and 4-40 nuts. (The holes are for the battery option.)

Install 2-D fasteners at the two locations marked B in Figure 7-1. The 2-D fasteners should line up exactly with the edges. Use two chassis screws per 2-D fastener.

(38 cm)

Figure 7-1

Page 77

76 ELECRAFT

Using a sharp tool, cut through and peel off about 1/2" x 1/2" (12 x 12 mm) of the masking material covering the EXT SPKR hole. Note: Leave the other holes covered with masking material until the associated options are installed.

Ground

Install the external speaker jack in the EXT SPKR hole. Orient the jack as shown in Figure 7-1 and Figure 7-4, with the "AF" tab nearest the inside of the top cover. (Caution: Mis- identification of the three tabs could result in a ground short.)

24" (61 cm) of 2-conductor speaker cable is supplied. Cut it into two pieces, 15" (38 cm) and 9" (23 cm) long.

Solder crimp pins to the two wires at one end of the 15" (38 cm) length of speaker cable (Figure 7-3).

Copper wire

Pin 1 side

Housing

Crimp pin

Figure 7-3

When you insert crimp pins into the housing in the next step, they should snap into place. Each pin has a small tab on the back that latches into a hole in the housing when inserted.

Copper wire

Figure 7-4

Connect one end of the 9" (23 cm) speaker cable to the speaker terminals. The copper wire should be connected to the lug marked (+) on the speaker. Solder both wires.

Connect the other end of this cable to the external speaker jack as shown in Figure 7-5. The copper wire must be connected to the lug marked "SP" below. Solder all three lugs.

Ground

Copper wire

Insert the copper wire into the pin 1 position of a two-pin

housing as shown. Insert the other wire into the pin 2 position.

Connect the other end of this cable to the external speaker jack as shown in Figure 7-4. The copper wire must be connected to the "AF" lug of the speaker jack. Solder only the copper wire.

Figure 7-5

Use three cable ties at the points shown in Figure 7-1 to hold the speaker cables in place. (Save the fourth cable tie for use with the supplied RF probe.) The ties should be pulled tight. Trim any excess cable tie length.

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ELECRAFT 77

Finishing Touches

Examine the Control board one last time to be sure that it is correctly plugged into the RF board. All three connectors must be mated completely.

Leave the frequency counter test cable connected to the BFO test point (TP2). This will allow you to modify your filter and BFO settings if necessary during normal operation.

If there are any missing chassis screws in the bottom cover, heat sink, side panels, or front panel, install them now.

Plug the internal speaker cable into P5 on the RF board, just behind the on-off switch, S1. The connector is keyed and can only be plugged in one way.

Even if you have purchased some K2 options, you should not assemble and install them yet. The option manuals assume that you are familiar with basic K2 operation.

Remove the masking material from the two top-cover

mounting holes marked C in Figure 7-1.

Cut through and peel off about 1/2" x 1/2" (12 x 12 mm) of masking material from around the top-cover mounting holes marked D in Figure 7-1. These holes are in the far corners of the top cover's rear panel, corresponding to screws 1 and 2 in Figure 7-6.

Attach the self-adhesive serial number label to the rear panel

of the heat sink in the space provided.

Write the serial number on the inside cover of your manual.

Figure 7-6

This completes assembly of your K2. Please read the Operation

section, which follows, and try each of the K2's features.

Place the top cover onto the chassis and secure it using six chassis screws as shown in Figure 7-6.

When removing the top cover in the future, take out only

the six screws shown in Figure 7-6.

If you did not have access to a frequency counter or calibrated receiver when aligning the 4-MHz oscillator, you may wish to use the one of the alternative VFO calibration techniques described in the Operation section (page 98). You can use an on-air signal, such as WWV at 10 MHz, to obtain better than +/- 50 Hz VFO dial calibration on all bands.

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78 ELECRAFT

8. Operation

BAND AND

MEMORY

SELECTION

RCL

BAND

STORE

EDIT

MODE

ANNUNCIATORS

DISPLAYBAND MODE

RF/ALC

ANT 1/2

TUNE

E L E C R A F T

59+2040

RF357 10

ALC

KEYER

POWER

K 2

NB ANT2 PRE ATT A B RIT XIT

T R A N S C E I V E R

LEVEL

AF GAIN

RF GAIN

INDICATOR

RATE

LOCK

VOX

PRE/ATT

SPOT

RIT XI T

PF1 PF2

-1 +1

NUMERIC

KEYPAD

(1-9)

A=BA/B

SPLITREV

AGC

456

XFIL

AFILCW RV

MSG

REC

ON OFF

MICROPHONE

JACK

VFO

K2 FRONT PANEL

NUMERIC

KEYPAD (0)

RIT/XIT

OFFSET

POWER ON/OFF

Page 80

ELECRAFT 79

INTERNAL BATTERY

DISABLE SWITCH

HOST ADAPTER

AND AUX I/O

ATU OPTION

TRANSVERTER OPTION

INT. BATTERY

OFF

AUX. I/O

12VDC

12V BATTERY OR

POWER SUPLY

ANTENNA

50Ω

MAIN ANTENNA

(DO NOT USE IF

ATU IS INSTALLED)

GND

ANT 1 ANT 2

UNBAL

ANTENNA TUNER

RCV. ANT.

LECRAFT SER. NO.

SEPARATE RECEIVE

ANTENNA (PART OF

160M/RXANT. OPTION)

EXT. SPKR

IN OUT

XVTR

KEYER PADDLE, EXT. KEYER, OR

HANDKEY

KEY

K2 REAR PANEL

Page 81

80 ELECRAFT

This section of the manual explains how to set up and operate the K2. Refer to the K2 FRONT PANEL and REAR PANEL illustrations on the previous pages for control locations.

Connections

Power Supply

You can power the basic K2 (without the KPA100 amplifier) from any 9-15 V DC power supply. A mating connector for the DC input jack is provided with the kit. Current drain is typically

1.5-2 A on transmit, but can be over 3 A at the highest power settings or with high SWR. (See Current Limiting, below.)

Internal Battery: An optional 12 V, 2.9-Ah rechargeable battery can be installed inside the K2 (model KBT2). A 14.0 V power supply can then be used to recharge the battery and power the transceiver. If an external battery is connected, the internal battery must be disabled using the INT BATTERY switch (rear panel). This will prevent undercharging of the internal battery.

Low Battery Warning: If the battery (or power supply) voltage drops below about 11 V, you’ll see a brief L O B A T T message flashed on the LCD once every 8 minutes (approx.). If this happens, you should reduce power and recharge your battery as soon as possible. For tips on extending battery life, see page 97.

Self-Resetting Fuse: If the K2's internal 12 V line is shorted to ground, fuse F1 will temporarily open, limiting current drain to about 100 mA. The display will remain blank. If this happens, turn power off until the problem is located and corrected.

Antenna

A well-matched antenna (50 Ω) or an antenna tuner should be used with the K2. Some high SWR conditions may result in excessive current drain unless power is reduced.

If you have the KAT2 antenna tuner option installed, the K2's power control and power output display will be much more accurate under all SWR conditions.

Keying Devices

Any type of hand key, bug, or external keyer can be plugged into the KEY jack, or you can use the K2's built-in memory keyer. In all cases, you must use a stereo plug with the keying device (a suitable plug is provided with the kit). Also see CW Operation (page 92).

Microphone

A standard 8-pin microphone jack is provided on the front panel. A jumper block on the front panel PCB is used to configure the mic jack for specific microphones. Refer to the SSB adapter manual.

Headphones

Any type of mono or stereo headphones at nearly any impedance will work with the K2. However, for best results we recommend highquality stereo headphones with full ear covers and 1/8" (3 mm) plug.

External Speaker

Current Limiting: You can specify the maximum transmit current (see C A L C U R , page 84). You'll see H I C U R on the LCD if the programmed limit is reached.

50/60-Hz Interference: Do not place the K2 beside, or on top of, any equipment that uses a large AC power transformer. This could result in modulation of the K2's low-level signal sources.

The K2 has a built-in, high-sensitivity 4-ohm speaker. You can also plug in an external 4 or 8-ohm speaker at the "EXT. SPKR" jack.

Option Connectors

A number of mounting holes are provided on the back panel of the K2 for specific option connectors. See Options (page 110).

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ELECRAFT 81

Controls and Display

LCD and Bargraph Meter

The LCD shows the operating frequency and other information depending on selected display mode. The LED bargraph functions as an S-meter on receive, and RF out or ALC meter on transmit.

Power-Up Messages: The LCD will display E L E C R A F T for two seconds on power-up. If a problem is detected, the display will show I N F O 1 0 0 or a similar message. The number shown corresponds to a paragraph in the Troubleshooting section.

Mode Indicator: A letter at the right end of the display tells you the operating mode: C (CW), L (LSB), or U (USB). A fourth mode, RTTY/data, can also be enabled, and uses the letter r (page

101). If a small bar appears above the C or r , it means that the CW sideband is inverted (CW reverse or DATA reverse). The mode indicator will also flash slowly in two cases: CW T E S T mode (see page 93) and S P E E C H (VOX) mode (see page 95).

Annunciators: The LCD provides eight Chevron-shaped annunciators, or status indicators:

SPLIT/RIT/XIT LED (Optional)

You can install an LED on the front panel that will turn on whenever SPLIT, RIT, or XIT is in effect. See the associated application note, Adding a SPLIT/RIT/XIT LED to the K2.

Potentiometers

AF GAIN receiver audio level

RF GAIN receiver RF level

Turning this control CCW (counter-clockwise) decreases receiver RF sensitivity. At the same time it increases the bargraph S-meter indication to remind you that you’re not at full receive sensitivity. The farther CCW the control is set, the stronger a signal must be before it results in a meter deflection.

KEYER keyer speed control

When you turn this control, keyer speed in words per minute (WPM) will be displayed, e.g. S P D 1 8 . The speed can be set from about 9 to 50 WPM.

NB noise blanker on (flashes if Low Threshold setting

is selected using ANT2 ant. 2 selected (requires ATU) PRE pre-amp on (approx. +14 dB) ATTN attenuator in (-10 dB) A VFO A selected (flashes in SPLIT mode) B VFO B selected (flashes in SPLIT mode) RIT RIT turned on (flashes if wide range selected) XIT XIT turned on (flashes if wide range selected)

Decimal Points: The decimal point to the right of the 1 kHz digit will flash slowly if the VFO is locked by holding Advanced Operating Features for other cases where decimal points flash (scanning, page 96; AGC OFF, page 97).

L E V E L )

L O C K . See

POWER power output control

When you turn this control, power output will be displayed in watts, e.g. P 5 . 0 . The range is 0.1 to 15 W for the basic K2, and 1 to 100 W if you have the KPA100 amplifier installed. See Basic K2 Operation for details on controlling power output (page 90).

OFFSET RIT/XIT offset

This control provides a default range of +/- 0.6 kHz in 10 Hz steps when

R I T and/or X I T are enabled. You can also select a wider

RIT/XIT range (see R I T menu entry, page 101).

As in many transceivers, this control actually varies the I.F. gain.

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82 ELECRAFT

Switch Functions

Each pushbutton switch as two primary functions, indicated by the upper and lower labels.

H O L D a switch for over 1/2 second to access its lower function.

Numeric Keypad: In addition to their tap/hold functions, ten of the switches are labeled with digits 0 through 9. A digit can be entered using either a TAP or HOLD (e.g.

the difference between the two is significant, as indicated below.

Tap and Hold Functions

B A N D + select next higher band

R C L recall memory #0 -9 (to start scan, use #0 -9 )

B A N D - select next lower band

S T O R E store memory #0 -9 (to start scan, use #0 -9 )

M E N U enter the menu

E D I T edit current menu parameter

D I S P L A Y select display mode (freq., voltage/current, time*)

R F / A L C select SSB transmit bargraph mode (RF or ALC)

A N T 1 / 2 toggle between ATU antenna jacks 1 and 2*

T U N E key transmitter; activates ATU if installed

T A P a switch to access its upper function;

5 , or 5 ). In some cases

P R E / A T T turn on preamp or attenuator

S P O T CW audio spot signal on/off

R I T turn on RIT (see R I T menu entry, page 101)

P F 1 activate programmable function 1

A / B select A or B VFO

R E V temporary A/B VFO swap (used in SPLIT)

A G C select FAST/SLOW AGC

C W R V toggle between CW norm/reverse or USB/LSB

X I T turn on XIT (see R I T menu entry, page 101)

P F 2 activate programmable function 2

A = B set both VFO’s to current VFO frequency

S P L I T toggle between SPLIT and NORMAL transceive

X F I L select next crystal filter (FL1-4)

A F I L audio filter mode (OFF, AF1, AF2)*

M S G play or chain CW msg #0 -8 (to repeat, use #0 -8 )

R E C record CW message #0 -8 (M S G cancels record)

Two-Switch Combinations

Press and hold the two indicated switches simultaneously:

N B select noise blanker mode (OFF/NB1/NB2)*

L E V E L toggle noise blanker threshold (low or high)*

R A T E select VFO tuning rate (see R A T E S menu entry)

L O C K lock/unlock VFO (DP flashes)

M O D E select operating mode (CW/LSB/USB)

V O X CW: oper/test; SSB*: PTT/speech 0.4/speech 1.0

*These functions require option modules; see page 110.

B A N D + + B A N D - direct frequency entry (e.g., #7 0 4 0 )

P R E / A T T + A G C AGC on/off (mode letter dec. pt. flashes)

X F I L + A G C display crystal filter # and bandwidth

(plus audio filter setting, if applicable*)

D I S P L A Y + T U N E override ATU T U N E power limit*

R I T + X F I L turn FINE RIT on/off (see page 99)

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ELECRAFT 83

Using the Menu

There are two menus: primary and secondary. You'll use the primary menu far more often; see list at right. The secondary menu is described starting at page 100.

To access the menu: Tap menu entry last used, with an underline. For example, you might

see: L C D D A Y , indicating that the LCD is in "day" mode (i.e., backlight off). You can scroll to a desired menu entry by turning

the VFO knob or by tapping the

To modify a menu entry's parameter: Hold underline to the parameter, rather than the menu entry name. In the case of L C D , the parameter can be D A Y or N I T E

the parameter using the VFO knob or B A N D + / B A N D - . When you’re finished, tap

M E N U will return you to normal operation.

D I S P L A Y Switch Usage in E D I T Mode: The D I S P L A Y switch

M E N U to return to scrolling. Another tap of

is used to access supplemental parameters when editing certain menu entries (marked "*" at right). You will normally not need to change these settings. Entries which use

Entry

D I S P L A Y Switch Usage in E D I T mode

S T L Selects the sidetone source, U 6 - 2 5 or U 8 - 4 . Use

U 8 - 4 (default) with the revision B RF board. T - R Specifies "8R" behavior, 8 r h o l d or 8 r n o r .

"Hold" mode (default) holds the 8R line low during

the user-programmed QSK delay.

I N P Selects auto-detect mode, A D E T O n (default) or

A D E T O f f .

E D I T Shortcut: If the menu entry you want to change is the last

one used, you don't need to tap parameter as usual, then exit by holding

M E N U . The display will show the

B A N D + and B A N D - switches.

E D I T to move the

. Change

D I S P L A Y include:

M E N U ; just hold E D I T . Change the

E D I T once more.

Primary Menu Functions

All primary menu functions are listed below (secondary menu functions are listed on page 100). Supplemental parameters accessed with

D I S P L A Y are marked (*); see explanation at left.

S T L sidetone level (volume): 0-255 (Tone Source*) S T P sidetone pitch: 0.40 to 0.80 kHz in 10 Hz steps T - R QSK delay: 0.00 to 2.55 sec. (8R Mode*) R P T CW message repeat interval: 0 to 255 seconds I N P CW input selection (Auto-detect on/off*):

P D L n (internal keyer/norm. w/auto-detect P D L r (internal keyer/reversed w/auto-detect)

H A N D (hand key or external keying device) I A B iambic mode: A or B S S B A SSB audio level (mic gain): 1 , 2 , 3 , or B A L S S B C SSB speech compression level: 1 - 1 through 4 - 1 ;

in RTTY/data mode, a separate compression

level is provided, and the menu entry is S S B C r

L C D D A Y (backlight off, bargraph bright) or

N I T E (backlight on, bargraph normal) G R P H LED bargraph selection: O F F , D O T , B A R

(O P T B A T T overrides G R P H B A R , forcing

D O T mode) O P T receiver optimization: P E R F o r m a n c e or

B A T T e r y (see page 97) A T U ATU operating mode R A N T RX antenna: O F F or O N , per-band (page 97) C A L calibration submenu (page 84) P F 1 / P F 2 programmable functions (page 97); can be

assigned to any menu function, S C A N , or

F P o n (Fast-Play)

If auto-detect is turned on, a computer, hand key, or external keyer can be

connected along with the paddle. See page 92.

)

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84 ELECRAFT

Calibration Functions

The C A L menu provides the following functions:

F C T R frequency counter C U R programmable transmit current limit T P A PA temperature set (see KPA100 manual) S L O S-meter zero set S H I S-meter full-scale sensitivity set P L L VFO linearization F I L filter settings (see next page)

After selecting a C A L function, hold

Frequency Counter (CAL FCTR)

C A L F C T R displays the frequency of the signal at P6 on the Control board during alignment (see page 57).

Transmit Current Limit (CAL CUR)

C A L C U R allows you to set a safe maximum transmit current. The recommended setting is 3.50 A. A lower setting may be appropriate if you're using 5 watts or less, or if your power supply has a lower current rating.

S-meter Calibration (CAL S LO, CAL S HI)

To set the S-meter zero level:

1. disconnect the antenna

2. make sure the RF GAIN control is fully clockwise (max gain)

3. select C A L S L O in the menu

4. turn the VFO knob until the left-most bargraph segment is just

barely turned off

5. exit C A L mode by tapping

E D I T to activate it.

M E N U

To set the S-meter sensitivity:

1. disconnect the antenna

2. turn the RF GAIN control fully counter-clockwise (minimum

gain)

3. select C A L S H I in the menu

4. turn the VFO knob until the right-most bargraph segment is just

barely turned off

5. exit C A L mode by tapping

Note: The S-meter must be recalibrated anytime the AGC threshold is changed. The AGC threshold adjustment is described on page 46.

M E N U

VFO Linearization (CAL PLL)

The C A L P L L function automatically calibrates VFO fine-tuning You can repeat C A L P L L at any time, although this should not normally be necessary. One reason you might re-run C A L P L L is after calibrating the frequency counter (see Advanced Operating Features, page 98). In general, you'll need to re-run C A L P L L and C A L F I L anytime you change the setting of C22 (Control board), which is used to align the 4 MHz crystal oscillator.

To Linearize the VFO:

1. Remove the top cover. The bottom cover must be installed

2. Allow a 10-minute warm-up period at room temperature.

3. Connect the internal frequency counter cable to TP1 (VCO).

4. Exit the menu if you were using it.

5. Switch to 40 meters and set the VFO anywhere in the 7000-7100

kHz range.

6. Use the menu to activate C A L P L L .

7. When calibration is completed (4-8 minutes), you'll hear a short

alert tone and see E n d on the LCD. You can then tap any switch to return to normal operation.

What you're actually calibrating is the relationship between the PLL (phase-

locked loop) divider and the crystal reference oscillator. (See Circuit Details.)

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ELECRAFT 85

Filter Settings (CAL FIL)

This section explains how to use C A L F I L to select the bandwidth and BFO settings. An example appears on the next page. The Elecraft web site provides information on other filter setup methods, including a method that uses a personal computer sound card. For a discussion of how the crystal filter and BFO settings are related, see page 104.

Basic CAL FIL Setup

1. Connect the frequency counter test cable to TP2 (BFO).

2. Set AF GAIN high enough to hear some background noise.

3. Switch to a band between 160 m and 17 m. (The sideband is

inverted on 15 m and above, which may be confusing during filter setup.)

4. Select CW mode using

the K2 is in CW Reverse mode; hold Normal mode.

5. Tap

6. Tap

X F I L until F L 1 is selected. M E N U and scroll to C A L . Hold E D I T to move the

underline to O F F , then scroll until you see C A L F I L . Finally, hold

E D I T again to activate the filter display.

Filter Bandwidth Display

The initial C A L F I L display shows the present filter bandwidth and the operating mode, e.g. F L 1 1 . 5 0 c . The number 1 . 5 0 indicates a bandwidth of roughly 1.50 kHz. a range of 0 . 0 0 - 2 . 4 9 . Above 2 . 4 9 , the parameter changes to O P 1 - O P 5 , which can be used to select optional filters. For example, the filter on the SSB adapter (KSB2) is O P 1 .

M O D E . If a bar appears above the C,

C W R V to select CW

This parameter has

BFO Displays

Tap

B A N D - to display the BFO setting for filter FL1, which will be

similar to B F 1 t 1 1 0 c . The 3-digit number is the BFO control parameter. This number can be changed using the VFO knob, but

you'll use a different BFO-setting method described below. The letter t after B F 1 is a reminder that the B F 1 BFO frequency is always used on transmit, which is important for SSB operation.

Whenever the BFO control parameter is displayed, you can tap

D I S P L A Y to show the actual BFO frequency in kHz. The VFO knob

can then be used to set the BFO directly. This method is used in the filter-setup example.

Note: After changing the BFO setting, you can tap

A G C to re-

measure and save the BFO information without switching filters. This is useful if you want to try various BFO settings for a particular filter to find the one with the best audio peak.

Other CAL FIL Operations

When you're in C A L F I L you can always tap next filter, tap

M O D E to change modes, and hold C W R V to switch

X F I L to change to the

from CW normal to CW reverse. Whenever you switch modes or filters, the K2 will first record your new settings, if they have been changed.

B A N D + switches to the filter bandwidth display, and B A N D - switches

to the BFO display. Tapping

M E N U exits C A L F I L and returns to

the normal display. (On exit from C A L F I L , changes are saved.)

Turning Selected Filters Off

Note the present bandwidth setting, then try using the VFO knob to change it. You'll hear the "shape" (or pitch) of the noise change. (Return to the original bandwidth after experimenting.)

The number shown should be used only as a relative indication of filter

bandwidth. Actual bandwidth will probably be narrower.

FL2, 3, or 4 can be individually disabled. To turn off a filter, display the filter bandwidth using C A L F I L , then set the bandwidth number to O F F . (To get to O F F , go to 0 . 0 0 first, then turn the VFO knob a bit farther counter-clockwise.)

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86 ELECRAFT

CAL FIL Example (setting up all filters):

Table 8-1 shows the recommended filer settings for a CW-only K2. If you already have the SSB adapter installed, use the SSB settings from the KSB2 manual.

1. Read the CAL FIL instructions on the previous page if you

haven't already. You'll need to be familiar with CAL FIL displays and controls before proceeding.

2. Do the Basic CAL FIL Setup from the previous page

exactly as described. You should then see a display similar to F L 1 1 . 5 0 c .

3. Using the VFO knob, set F L 1 to the value shown for CW

Normal (1.50). Tap

X F I L to save the new value and move to

F L 2 . (The CW Reverse bandwidth will also be updated.)

4. Set up F L 2 , F L 3 , and F L 4 in the same manner.

Table 8-1. Recommended Filter and BFO Settings, CW-only K2

Mode FL1 BF1 FL2 BF2 FL3 BF3 FL4 BF4

CW Norm. 4913.6 4913.2 4913.2 4913.1

CW Rev.

1.50

4915.0

0.70

5. Use

6. Tap

X F I L to return to F L 1 . Tap B A N D - to show B F 1 .

D I S P L A Y to show the actual BFO frequency. Use the VFO

knob to select the value shown in the table. Typically you'll be able to get to within +/- 20 Hz of the target frequency.

7. Tap

X F I L to save the new value and move to B F 2 . Repeat steps

6 and 7 to set up B F 2 , B F 3 , and B F 4 .

8. Switch to CW Reverse by holding

C W R V . Then repeat steps 6

and 7 for each CW Reverse BFO setting (B F 1 -B F 4 ).

9. Tap

B A N D + to return to the filter bandwidth display. Use the

M O D E switch to select LSB, and return to F L 1 using X F I L .

10. Set up each LSB filter bandwidth according to the table. (This

also updates the USB filter bandwidths.)

11. Tap

12. Tap

B A N D - and set up each LSB BFO as you did for CW. M O D E to select USB, and set up each USB BFO.

13. If you use settings that differ from the defaults, record them in

Table 8-2. Use pencil, since you may change them later.

4914.4

0.40

4914.4

0.20

4914.4

LSB 4913.7 4913.7 4913.5 4913.5

USB

2.20

4916.0

2.00

4915.7

1.80

1.60

4915.6

Table 8-2. Filter and BFO Settings Used (record in pencil)

Mode FL1 BF1 FL2 BF2 FL3 BF3 FL4 BF4

CW Norm.

CW Rev.

LSB

USB

4915.3

Page 88

ELECRAFT 87

Basic K2 Operation

Mode Selection

Tap M O D E to cycle through the operating modes, noting the change in the mode indicator letter (C = CW, L = lower sideband,

U = upper sideband). If RTTY/data mode is enabled, r = RTTY/data will also appear in the mode list (see page 101).

Sideband Inversion: The K2 inverts the sideband on 15 meters and above due to the frequency mixing scheme (the upper and lower sidebands of the signal become reversed). In CW Normal mode, the pitch of CW signals goes up with frequency on the lower bands; on 15 m and up, the pitch goes down with frequency.

Receiver Configuration

Gain Controls: The RF GAIN control should normally be set fully clockwise. Adjust the AF GAIN control for comfortable volume. Sidetone volume is set using S T L (page 93).

Crystal Filter Selection: Each operating mode provides up to four filter settings, FL1-FL4. Bandwidth and BFO settings can be customized using C A L F I L (page 85)

through the filters. FL2, 3, or 4 can also be turned OFF.

Filters and Operating Modes: The CW Normal and CW Reverse crystal filter selections are tied together. For example, if you switch to FL2 when in CW Normal mode, CW Reverse also switches to FL2. The same applies to the LSB and USB modes.

Checking Filter Status: You can check the current filter number and its bandwidth without changing filters by holding

X F I L + A G C . For example, you might see F L 2 0 . 8 0 c . If the

KAF2 audio filter is installed and the CW filter is enabled, you'll see A F 1 or A F 2 following the crystal filter display.

Bandwidth settings below 0 . 2 0 may cause excessive signal attenuation.

. Tapping X F I L cycles

Audio Filter Control: If you have the KAF2 option (audio filter and real-time clock) installed, holding

A F I L will allow you select its

operating mode.

Preamp: When operating on higher bands, you'll probably want to use the preamp (about +14 dB) to improve the overall signal-tonoise ratio. If you experience very strong in-band interference, you may need to turn the preamp off.

Attenuator: If necessary, an additional 10 dB of attenuation can be switched in by turning on the attenuator. This is more effective than using the RF GAIN control in the case of strong-signal overload.

Scanning: See Advanced Operating Features, page 96.

Antenna Selection: If you're using a KAT2 or KAT100

automatic antenna tuner, the

A N T 1 / 2 switch will toggle between

the two ATU antenna jacks. This also instantly recalls the ATU's stored L-C parameters for each antenna. Refer to the relevant ATU manual.

Noise Blanker Controls: The KNB2 option is required to use these controls. The noise blanker is always turned OFF on powerup, and you should leave it off unless needed. When it is turned on, the receiver will be more susceptible to interference from strong signals. To turn on the noise blanker, tap the

N B switch. You’ll see

N B 1 , N B 2 , and O F F in that order. The N B 1 and N B 2 modes

provide short or wide pulse blanking intervals, respectively. One may be more effective than the other, depending on the type of noise. In either mode, the NB annunciator will turn on.

The noise blanker provides two thresholds of noise detection: high and low. If you hold

L E V E L the noise blanker will toggle between

these two modes, with the display showing H I T H R or L O T H R . High threshold is the default and should be used in most cases. If you select low threshold, the noise blanker may be more effective on certain types of noise, but it will also leave the receiver more vulnerable to strong in-band signals. When L O T H R is selected, the NB annunciator flashes as a reminder.

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88 ELECRAFT

LCD and Bargraph Configuration

Day/Night Selection: If you're operating outdoors, use the menu to select L C D D A Y , which turns off the LCD backlight and puts the bargraph into high-brightness mode. Indoors or at night, use L C D N I T E , which turns the backlight on and reduces the bargraph brightness.

Bargraph Modes: You have a choice of O F F , D O T , or B A R for the LED bargraph. If you select D O T , just one bargraph segment representing the current meter level will be illuminated. If you select B A R , all LED segments to the left of the current level will also be illuminated, resulting in a more visible display. O F F mode turns off the bargraph completely during receive but uses DOT mode on transmit (see Advanced Operating Features).

Display Modes: Tapping the frequency display mode and voltage/current display mode. If you

have the KAF2 option installed (audio filter and real-time-clock), a time/date display mode will also be available.

In frequency display mode, the LCD will show the operating frequency, mode indicator, and any annunciators that are enabled, e.g. 2 4 9 4 5 . 0 4 c . This is the display you’ll use most often.

In voltage/current display mode, the LCD will show supply voltage (E) in 0.1 V increments and supply current (I) in 0.02 A increments, e.g. E 1 3 . 8 i 1 . 4 0 . Voltage/current display is useful for monitoring battery condition and transmitter performance. It can also be used in conjunction with a simple voltage probe to check DC voltages inside the K2. A two-position jumper on the Control board, P7, selects either 12 V monitoring or the voltage probe (P5). If the voltage/current display shows 0 . 0 volts, it is likely that you have P7 in the probe position.

In time/date display mode, the LCD will show either time (e.g. 0 8 . 0 5 . 0 0 ) or date (e.g. 1 1 - 2 8 - 0 2 ). You can toggle between time and date by holding

B A N D + and B A N D - together. Refer to the

KAF2 manual for details on setting the time and date.

D I S P L A Y switch alternates between

Frequency and Band Selection

The basic K2 kit covers the 80 through 10 meter bands. 160 meter coverage can be added with the K160RX option, and 60 meters with the K60XV. You can tune well above and below the ham

bands.

Transverter Bands: The K2 provides up to three programmable transverter band displays for use with external transverters. Refer to the T R N x menu entry (page 102).

Transmit Limits: Some countries require transmit to be disabled outside of specified amateur bands. If you key the transmitter with the VFO set outside fixed limits, you’ll see E n d on the LCD.

You can change bands in one of three ways:

• tap

• hold R C L (memory recall); see below

• use Direct Frequency Entry (described later)

Whenever you change bands or recall a frequency memory, a number of parameters are saved in nonvolatile memory (EEPROM). This update also occurs periodically if you’ve moved the VFO (see Backup Timer). The parameters that are saved on a per-band basis include:

• A and B VFO frequencies and VFO tuning rate

• Current VFO (A or B)

• Operating mode (CW, USB, LSB) and CW Normal/reverse

• AGC slow/fast

• Preamp and attenuator on/off

• Noise blanker on/off (requires noise blanker option)

• ANT1/2 selection (ATU option)

• Receive antenna on/off (160 m/RX ant. option))

are used at the front end to reject out-of-band signals. If you attempt to tune too far outside an available band, receiver sensitivity and transmit power will greatly decrease, and at some point the synthesizer will lose lock.

B A N D + or B A N D -

The receiver is not intended to be general coverage; narrow band-pass filters

Page 90

ELECRAFT 89

Default Frequency Memories: When you first turn on the K2, each band memory is preset as follows:

• VFO A is set to the first multiple of 100 kHz above the band

edge (e.g. 7100, 24900).

• VFO B is set to the U.S. CW QRP frequency for that band

• Other defaults include: CW mode; VFO A; fast AGC; preamp

ON above 40 meters and OFF on 40 m and below; noise blanker OFF and high threshold; antenna 2 OFF (antenna 1 selected); receive antenna OFF (normal receive operation)

Memories #1-8 are preset to the same values as the 160-10 meter band memories, respectively.

Store and Recall: Ten memories are provided, numbered 0 through 9. Each memory stores the same information that is stored per-band.

To store the current setup in a frequency memory, hold

S T O R E

until you see E N T 0 - 9 , then tap one of the numeric keypad switches. To recall a stored setup, hold

R C L until you see E N T 0 -

9 , then tap the number of the memory you wish to recall. In both

cases you can cancel the operation by tapping any non-numeric switch.

Note: If you hold rather than tap a numeric keypad digit when doing either a store or recall, you will initiate scanning. (See page

96.)

Direct Frequency Entry: To do direct frequency entry, hold both

B A N D + and B A N D - simultaneously. When you see "-----" on the

LCD, release the two switches, then enter the target frequency using the numeric keypad. To enter a frequency in the 160 meter band, you must enter 5 digits, starting with a leading 0, e.g.

5 . For other bands below 10 MHz, you need only enter 4 digits

(e.g.,

7 0 4 0 ). On transverter bands, direct frequency entry can

0 1 8 3

only be used to go to a new frequency within the present band. (see T R N x menu entry, page 102).

There are three possible results from using direct frequency entry:

• If you enter a frequency within the current band, only the

current VFO will be updated.

• If you enter a frequency that is in a different band, a band

change results, and the entire configuration for the target band will be loaded, except that the current VFO will now be at the frequency you just entered.

• If you enter a frequency that is too far outside any available

band, you’ll be switched to the closest available band, and the frequency will be set to the one last used on that band. For example, if you try to switch to 8400 kHz--which is typically outside the range of the synthesizer--the K2 will switch to 40 meters and setup the VFOs as they last were on this band.

Tuning Rates: The VFO tuning rate is selected by tapping

R A T E .

Default tuning rates include 10 Hz, 50 Hz, and 1 kHz per step, resulting in 1 kHz, 5 kHz, and 100 kHz per VFO knob turn. Other tuning rates can be selected; see the R A T E S menu entry (page

100).

The frequency display changes to remind you of the current tuning rate. At 10 Hz/step, two decimal places are shown (100 Hz and 10 Hz). When you select 50 Hz/step, the 10 Hz digit is blank. When you select 1 kHz/step, both decimal places are blank.

VFO Lock: The current VFO frequency can be locked by holding the

L O C K switch until L O C is displayed. The decimal point will

then flash slowly as a reminder. Split Operation: Lock applies only to the current (receive) VFO. So, while you are holding the

R E V switch (temporary VFO reverse), you can change the

frequency of the other VFO (transmit), overriding lock. This is very useful when operating SPLIT, since it allows you to check and modify your transmit frequency without unlocking the receive VFO.

Holding the switch again cancels lock and displays N O R (normal).

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90 ELECRAFT

Power Control

Turn the POWER control to set the power output directly in watts (e.g., P 5 . 0 ). The normal range of the control is 0.1 to 15 watts. If you have the KPA100 option installed and enabled, the range is

0.1 to 110 watts, with the amplifier module disabled at 10 watts or lower. In CW mode, you must send a few CW characters or press T U N E to allow the ALC (automatic level control) to lock-in the new power level.

Requested vs. Actual Power: The POWER control sets the requested power, which may exceed the actual power that the transmitter can achieve. To see actual power output, use below). In tune mode, the display always shows the actual power output (except when the display is showing voltage and current, or when the ATU is doing an autotune). The power displayed will be accurate to within about 10% if the load at the antenna is matched (50 ohms).

Using

T U N E : Hold T U N E to key the transmitter. You’ll hear one

beep when you start tune, and another when you terminate tune by tapping any switch or hitting the keyer paddle.

ATU: If you're using a KAT2 or KAT100 automatic antenna tuner, pressing

T U N E will drop power to either 2 or 20 watts maximum

(depending on whether the KPA100 is in use), and may trigger a retune of the antenna matching network. You can also override power reduction by holding

T U N E + D I S P L A Y (see page 91).

Current Limiting: To protect the transmitter and power supply/battery from excess current drain, you can program a transmit current limit using C A L C U R (see Calibration Functions).

T U N E (see

VFO Selection

To select the A or B VFO, tap A / B . To set the unused VFO equal in frequency to the current VFO, tap

A = B . The currently-selected

VFO will determine both the transmit and receive frequencies unless you’re running SPLIT (see below). A and B VFO frequencies are saved in EEPROM on a per-band basis, and are updated periodically (see Backup Timer at the end of this section).

Split and Reverse Operation

Split operation means transmitting and receiving on different frequencies. This is useful for DX work, since many DX stations will ask you to call them above or below their carrier frequency to avoid interference. To enter split mode, hold message S P L I T appears on the LCD. Holding display N O R (normal). The active VFO annunciator (A or B) will flash slowly when you’re in SPLIT mode to remind you that this feature is enabled and that your receive and transmit frequencies are different. Also, each time you transmit when in SPLIT mode, the transmit frequency is displayed for a minimum of 1/2 second.

When you're using split, you can switch between your transmit and receive frequencies by tapping

A / B . However, there are times when

you only want to quickly listen on your transmit frequency, not switch VFOs. In this case you can hold in the which temporarily swaps the VFOs. When you release REV, the LCD will return immediately to the receive frequency. When using split, experienced operators can simultaneously hold in the REV switch and adjust the VFO knob--all with one hand--to quickly find a clear spot to transmit. (

R E V overrides VFO lock as described

previously.)

S P L I T until the

S P L I T in again will

R E V switch (reverse),

You can install an LED on the front panel that will turn on whenever SPLIT, RIT, or XIT is in effect. See the associated application note, Adding a SPLIT/RIT/XIT LED to the K2.

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ELECRAFT 91

RIT and XIT

You can turn on RIT (receive incremental tuning) by tapping R I T . The RIT annunciator then turns on. It flashes slowly if you have

selected a wide-range RIT/XIT offset (see R I T menu entry, page

101). The OFFSET knob controls the receive offset.

The +1 and -1 kHz marks on the offset control apply only if the RIT/XIT range is set to +/- 1.2 kHz using the R I T menu entry. Regardless of the range used, the exact offset can be determined by comparing the VFO frequencies with RIT on and off.

When X I T is turned on, it works similarly to R I T , except that the transmit frequency is varied with the OFFSET control. This can be

useful for small-split operation (for example, when a DX station you're listening to says to call "UP 1" kHz), or to adjust your transmitted frequency at the request of another station. The transmitted frequency is not displayed during receive mode, so if you need to determine the exact setting of the offset control when using

X I T , you can briefly turn on R I T .

It's OK to have both

X I T and R I T on at the same time. In this case

the OFFSET control can be thought of as an extension to the main tuning knob, but covering only a small frequency range.

As with

S P L I T , if you have R I T or X I T enabled, the transmit

frequency will be displayed when you transmit, and the receive frequency will be restored a minimum of 1/2 second later.

FINE RIT: In some cases you may want to control the VFO in smaller steps to fine-tune signals on receive. This can be done using the FINE RIT feature, described on page 99.

Automatic Antenna Tuner (ATU)

Both the low-power internal automatic antenna tuner (model KAT2) and high-power external antenna tuner (KAT100) can match nearly any coax-fed or random-length antenna on multiple bands. ATU functions will be covered briefly here; refer to the specific ATU manual for details.

The operating mode of the KAT2 or KAT100 is selected using the A T U menu entry, and is normally set to A U T O . The menu entry also allows you to see the L and C selection, step through ATU relays, etc. Note: If you have both a KAT2 and a KAT100 connected to your K2, the A T U menu entry will control only the KAT100. The KAT2 will be placed in through mode (L and C = 0), and will be set to antenna 1.

The ATU is activated whenever you press

T U N E . The K2 display

will show SWR or forward/reflected power, depending on the tuner's mode. If a KPA100 is installed, its

T U N E display will be used. Power

is reduced to 2 watts during TUNE mode (20 watts if the KPA100 is enabled). This power reduction can be overridden by holding

T U N E + D I S P L A Y . In this case, no auto-tune will be attempted.

Two antenna jacks are provided on both ATUs, with the matching network data for both antennas stored on a per-band basis. You can tap

A N T 1 / 2 to switch antennas. Since the relays take only a small

fraction of a second to switch, it becomes practical to quickly try both antennas anytime the distant station is weak. This is particularly useful for Field-Day and similar contests, where you might use two end-fed random wires running in different directions.

Backup Timer

We did not include detent on the offset knob because experience has shown that knob detent mechanisms degrade over time, making it difficult to adjust the offset near the zero point. However, you can always return the offset knob to the zero point by simply matching the RIT-on and RIT-off frequency displays, or by turning RIT off.

While you're moving the VFO, a 30-second data backup timer is being continuously re-started. Once you have completely stopped tuning the VFO for at least 30 seconds, the K2 will then save your current operating frequency in EEPROM. As long as you stay on a particular frequency, no further updates will be done.

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92 ELECRAFT

CW Operation

The K2 provides a number of features for the CW operator:

 fast I.F.-derived AGC with fast/slow/off control  full break-in operation with no relays  accurate control of sidetone volume and sidetone pitch/offset  memory keyer with Iambic modes A and B,  nine programmable message buffers; chaining and auto-repeat  software-selectable paddle selection (normal or reverse)  multiple crystal filter bandwidths and opposite-sideband CW  dedicated  optional low-noise analog audio filter

Several advanced CW features are covered in later sections:

 Fast-Play ("one touch") message buffers (page 100)  Adjustable keying weight (page 100)  "smart" CW signal scanning (page 96)  FINE RIT for fine-tuning CW signals (page 99)

Keying Device Selection

A single connector in the back is provided for your keyer paddle, hand key, keyer, or computer. It is also possible to connect both a paddle and an external keyer or computer at the same time (see External Keying Auto-Detect, below).

S P O T switch for accurate signal pitch matching.

Internal Keyer: To use a keyer paddle, use the menu to choose

I N P P D L n or I N P P D L r (normal or reverse paddle). With P D L n selected, the "tip" contact on the stereo key jack is DOT and "ring" (the middle contact) is DASH. P D L r is the reverse.

External Keying Auto-Detect: If you wish to connect a handkey, external keyer or computer along with a keyer paddle, you can use the K2’s "auto-detect" feature. Simply connect your external keying device to the DOT and DASH lines through two diodes as shown in Figure 8-1, along with the keyer paddle. Be sure you have selected I N P P D L n or I N P P D L R in the menu.

TO K2 KEY JA CK

GROUND

DO T DASH

KEYLINE

1N5817, 1N4148, etc.

GROUND

PADDLE

H ANDKEY,

COMPUTER,

OR EXTERNAL

KEYER

You must use a stereo (2-circuit) plug, even if you use only a hand key or external keyer. This should not affect the use of the keying device with other equipment, since the middle contact on the plug (often called the "ring" contact) is only used with keyer paddles.

Hand key or External Keying Device: To use a hand key or external keying device, select I N P H A N D using the menu. Use the "tip" contact (DOT) of the key jack with a hand key or external keying device. You can key the K2 externally at up to 70 WPM.

Figure 8-1

When you connect the keying devices in this way, you can continue to use the paddle as usual. But if the external keying device is keyed, both the DOT and DASH lines will be pulled low simultaneously via the diodes. The K2 firmware interprets this as direct external keying rather than as DOT or DASH triggers.

Auto Detect can be turned off if desired. Find the I N P menu entry,

E D I T the parameter, then tap D I S P L A Y to select A D E T O F F .

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ELECRAFT 93

Basic CW Setup

Mode Selection: To place the rig in CW mode, tap the M O D E switch until the mode indicator changes to C.

Filter Selection: You can select one of the filters using the switch. FL1 is typically configured as the widest filter. If you have

the SSB adapter installed, you'll probably want to use C A L F I L configure FL1 as OP1 (SSB option filter) in CW and CW reverse modes, and leave FL2-4 at the narrower factory defaults (0.7, 0.4, and 0.1). Details on how to do this setup can be found in the SSB adapter manual.

CW Frequency Display: In CW mode, the frequency shown on the LCD takes into account an offset equal to your sidetone pitch. This allows you to determine a station's actual carrier frequency by matching their pitch to your sidetone, rather than by zero-beating the signal. The

S P O T switch can be used for this purpose.

Operate vs. Test mode: If you want to try out the keying without actually transmitting, hold the

V O X switch until the display

shows T E S T . The mode letter C on the LCD will flash to remind you that you have disabled transmit. Holding the

V O X switch in

again returns to O P E R a t e .

X F I L

The SPOT Switch

The S P O T switch can be used to zero-in on received signals or to test your sidetone pitch quickly, without having to key the transmitter or enter the menu. It’s important to use

S P O T before

using CW reverse. Once a signal has been SPOTted, you’ll only hear a slight change in pitch when you use the

When you use

S P O T , the receiver audio will not be muted. This

C W R V switch.

allows you to listen to another station and turn the VFO knob until the pitch of the received signal matches that of the sidetone. Once the two match, you’ll be very close to the station’s frequency if you call. (Exception: If you’re using

R I T , X I T , or S P L I T , your

transmit and receive frequencies will differ by more than just the normal transmit/receive offset. Turn off these features when using

S P O T .)

Unfortunately, matching audio pitch is a little tricky for some operators. Basically, you’ll need to tune the VFO up and down until the station you’re hearing seems to "disappear" under the sidetone-

-that is, until you can’t hear any difference between the two. When this happens, you’ll know the two pitches are matched.

Using the Internal Keyer

Sidetone Setup: Key the rig in T E S T mode and listen to the sidetone volume and pitch. To change the volume, use the menu’s

S T L entry (sidetone level). The pitch can be changed using the S T P entry (sidetone pitch). S T L is used often, so you might

want to assign it to

P F 1 or P F 2 (see Advanced Operating Features).

Break-in (QSK) delay: The QSK delay is set using the T - R menu option. A setting of 0 . 0 0 is fastest but some operators may find the keying harsh, in which case 0 . 0 1 is a good compromise. 0 . 0 5 is about right for casual operation. You can select a longer delay (up to 2.5 seconds) for slower CW work or to prevent un-muting when sending a repeating beacon message.

Two menu entries are provided to set up the keyer:

 I A B allows you to select Iambic mode A or B . (Mode A is

similar to Curtis mode A; mode B is similar to Super CMOS Keyer III mode B. If you aren't sure which to use, start with mode A, which has less critical timing requirements.)

 I N P selects paddle normal (P D L n ), paddle reverse (P D L r ), or

hand key/ext. keyer (H A N D )

These settings are stored in EEPROM, so you won’t lose them when you turn power off.

Use the KEYER control to select the desired CW speed. The display shows the speed in WPM as soon as you start turning the knob. You can adjust the keyer speed even while transmitting.

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94 ELECRAFT

Message Memories

The K2 provides nine CW message memories of 250 bytes each. Playback features include message repeat and 1-level chaining. CW messages can only be recorded using a keyer paddle connected directly to the K2's key jack. Set I N P to P D L n or P D L r .

To record a message: Hold numbered switch (#

0 -8 ) to select one of the nine message buffers.

The display will then show REC 250, indicating that 250 bytes of storage are available in this message buffer. This number will count down toward 0 as long as you are sending. Whenever you stop sending, up to two standard-length word spaces will be inserted. To stop recording, tap

M S G . If you do this before starting to send, the

original message contents will not be lost.

To play back a message: Tap (#

0 -8 ). Message play can be canceled at any time by hitting M S G

again or by tapping the keyer paddle. To listen to a message without transmitting, use T E S T mode (

Auto-Repeat: Any message memory can be auto-repeated when played. To auto-repeat, tap

numbered switch (#

0 -8 ). The message will then play back

continuously until you tap The buffer # will flash at the end of each transmission (e.g., B 6 ).

Note: You cannot change the frequency with the VFO knob during a repeating message, but you can use RIT (if enabled) to listen above and below your receive frequency between calls.

Setting the Auto-Repeat Interval: The length of the pause between messages during auto-repeat can be programmed using the

R P T menu entry (0-255 sec.). Long delays are useful for beacons.

R E C , and when prompted tap a

M S G , then select a message buffer

V O X switch).

M S G as usual, then hold the desired

M S G again or hit your key or paddle.

Message Chaining and chain/repeat: While a message is playing, you can tap #

0 -8 to chain a message onto the end of the

current one. The buffer number will be displayed twice: once when you hit the numbered switch, and again when the chained message starts. To chain a repeating message onto the current message, HOLD rather than TAP the numbered switch (i.e., use #

0 -8 ).

Chaining is useful during contests. For example, you might set up message 5 as "QSL 73" and message 6 as "CQ TEST DE N6KR." You could then hit

M S G 5 6 at the end of a QSO to sign with the

previous contact, then begin a repeating CQ.

CW Reverse

CW Reverse allows you to listen to CW using the opposite sideband. Sometimes this can eliminate or reduce interference from a strong station without reducing the strength of the desired signal. To switch to the opposite sideband, hold the

C W R V (CW reverse)

switch. A bar will appear above the mode letter C on the LCD. (Use

S P O T first to stay on frequency when you switch to CW reverse.)

Sidetone Pitch and Receive Offset

When you change the sidetone pitch using the S T P menu entry, you’re also changing the CW receive offset. The two always match within approximately 10 Hz. This ensures that when you listen to other stations at same pitch as the sidetone, your transmitted signal will be right on that station’s frequency.

To see how the receive offset tracks the sidetone pitch: Use to tune in a station at your current sidetone pitch as described earlier. Then use S T P to change the pitch. As soon as you exit the menu, you’ll notice that the station you were listening to has also been shifted to the new sidetone pitch.

Changing the sidetone pitch does not automatically re-adjust the BFO frequencies in relation to the crystal filter passband. So if you change your sidetone pitch, you should use C A L F I L to manually optimize the BFO settings.

S P O T

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ELECRAFT 95

SSB Operation

You can use SSB and RTTY/data modes if you have the KSB2 SSB adapter installed. Basic information on using the SSB adapter is provided here. For complete details, refer to the KSB2 manual.

SSB Controls

Operating Mode: Use M O D E to select L (LSB) or U (USB). To alternate directly between USB and LSB, use

used on 40 meters and below, and USB is used on the higher bands.

Crystal Filter Selection: If the SSB adapter is installed, you'll be able to take advantage of its 7-pole fixed-bandwidth filter. The fixed filter is designated OP1 in C A L F I L . In addition to its application to SSB and data modes, it can be used for CW and AM reception. Refer to the KSB2 manual.

SSB Menu Entries: S S B A is used to set the mic audio level (mic gain), from 1 to 3 . An additional setting, B A L , is used during SSB adapter alignment. S S B C is used to set the speech compression level, from 1 - 1 to 4 - 1 . Higher settings add "punch" and are especially useful at low power levels.

PTT/VOX Selection: By default the K2 uses PTT (push-to-talk) via your microphone’s PTT switch. To use VOX (voice-operated transmit), hold the S P C H 1 . 0 on the LCD. The number 0.4 or 1.0 is the approximate VOX delay time in seconds. Holding restores the setting to P T T .

Power/ALC Metering: If you have the SSB adapter installed, you’ll be able to switch between RF and ALC bargraph meter modes by holding may help in setting the mic gain and speech compression level. The ALC reading starts from the right end of the bargraph rather than the left, using BAR mode, so you won’t confuse it with the RF display. Use RF meter mode for normal operation.

R F / A L C . ALC metering is used only in SSB modes, and

V O X switch until you see S P C H 0 . 4 or

C W R V . LSB is usually

V O X again

Microphone Configuration

You’ll need to configure the MIC CONFIG header on the Front Panel board in order to transmit SSB on the K2. Most microphones with standard 8-pin connectors can be used. On many mics, the Up and Down buttons can be configured to switch between VFO A and B. You'll hear one beep on switching to VFO A, and two beeps when switching to VFO B.

RTTY/Data Operation

RTTY/data operation can be accomplished in SSB modes by using AFSK (audio frequency shift keying) or other modulation modes. Audio must be fed into the mic jack from a computer or modem, and the K2’s audio output routed to the computer or modem from either the headphone or speaker jack. Either LSB or USB can be used; this will probably be determined by your software. You can use either the SSB adapter's fixed filter (O P 1 ) or the variable- bandwidth crystal filter for receive purposes. On transmit, O P 1 is always used.

Since some RTTY/data mode duty cycles approach 100%, you should reduce power to about 5W or avoid transmitting at 10W for longer than 1-2 minutes at a time. (Power levels above 10 W are not recommended.) You can key the transmitter via either the key jack or the mic jack, since the DOT line is also the PTT line.

RTTY/Data Mode (mode letter r ): This is a special fourth mode of operation that provides independent crystal filter selections for use with RTTY, PSK31, etc. For details on configuring and using RTTY/data mode, see page 101.

FINE RIT: Fine RIT allows you to vary the receive frequency in increments smaller than 10 Hz. This is especially useful with PSK31 and other narrow-band data modes. See page 99.

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96 ELECRAFT

Advanced Operating Features

A number of specialized operating techniques are described in this section:

 Scanning (see below)  Reducing current drain for portable operation  Using a separate receive antenna  Programming the PF1/PF2 functions  AGC on/off control  VFO frequency calibration techniques  Checking firmware revision numbers  Resetting to factory defaults  Using computer control of the K2  FINE RIT mode

Also see Secondary Menu Functions (page 100).

Scanning

The K2's scanning feature lets the K2 tune any band segment continuously, keeping the receiver audio squelched until signals of interest are found. Scanning works for both CW and SSB signals, and when properly set up will ignore most stable carriers (key-down signals with no modulation).

Scanning is very useful for monitoring bands that may at first appear "dead." You may be surprised to find more activity than expected. The receiver will stay squelched until a signal appears.

Frequent scan users may wish to program RESUME as described at right.

P F 2 (or P F 1 ) to do SCAN

To use scanning:

 Setup VFOs A and B for the two ends of the band of interest.

VFO A must be set for a frequency lower than VFO B (a minimum of 2 kHz separation is recommended).

 Select the operating mode, preamp/attenuator setting, and

tuning rate (

 Store this setting in any memory (using the

R A T E ). Select a narrow filter if the band is noisy.

S T O R E switch), but

instead of tapping the switch for the desired memory, hold the numbered switch (

0 -9 ) to initiate scanning. You can also

initiate scanning when you recall a stored memory. Just hold

R C L , then hold the numbered switch in, as with S T O R E . The

memories can store up to 10 scan ranges for instant recall.

 During scanning, the MHz decimal point flashes. When a

station is found, the receiver will stay on that frequency for about 25 seconds or until the signal fades. Once a signal has disappeared or 25 seconds have elapsed, the frequency will be incremented by 0.5 kHz and scan resumed.

 If scanning seems to be locking onto noise too often, you can

tailor the lock rate by backing down the RF GAIN control. Also try using a narrower filter or turning off the preamp. You'll need to re-store the scan memory after making these changes.

 You can exit scan mode by tapping any switch or hitting your

key or paddle. Use SCAN RESUME (below) to restart scan.

Scan Resume: Often you may wish to stop scanning, then pick up where you left off. To do this, you can program

P F 2 (or P F 1 ) to do

scan resume. Once scan resume has been assigned to a programmable function switch, simply tap any switch or the keyer paddle to stop scan, and hold

P F 2 (or P F 1 ) to re-start it. You’ll

hear one BEEP when you stop scan, and another beep when you resume it. The frequency will jump up 0.5 kHz to avoid having scan re-lock on the same station.

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ELECRAFT 97

Reducing Current Drain for Portable Operation

You can use any of the methods listed below to reduce receivemode current drain and thus extend battery life. These techniques will have only a small effect on transmit current drain, however. Reduce power output to the lowest effective level if you're transmitting frequently on a weak battery.

 Use headphones or reduce speaker volume.  Turn off the RF preamp.  Set G R P H to D O T mode. There's also an O F F mode, which

completely disables the S-meter and forces D O T mode for transmit power display.

 Set O P T (Optimization) to B A T T (battery); this reduces the

I.F. post-mixer amplifier current by about 40 mA and automatically forces the bargraph to use D O T mode if set for B A R . Receive performance is minimally affected by this setting unless you have very strong in-band stations nearby.

 Set L C D to D A Y to turn off the L C D backlight. This is most

effective if you also set G R P H to O F F , since each bargraph LED segment that is turned on in D A Y mode uses about 18 mA. (Each segment uses only 6 mA in N I T E mode.)

Note: Voltage/current display mode can be used to verify the effect of each setting.

Programmable Function Switches (PF1/PF2)

The P F 1 and P F 2 switches (below R I T and X I T , respectively) can be programmed as direct edit shortcuts to any two menu entries of

your choice, including secondary menu entries (see page 100). Two special functions can also be assigned to (F P o n , page 100) and SCAN RESUME (S C A N , page 96).

To program

P F 1 or P F 2 : Enter the menu and scroll to P F 1 or

P F 2 , then change the parameter to the desired entry. Exit the

menu.

To use

P F 1 or P F 2 : HOLD one of these switches to activate the

selected menu shortcut, then change the menu parameter (which will be underlined) using the VFO knob or

return to normal operation, tap any switch or the keyer paddle. Exceptions: the F P o n and S C A N functions take effect immediately.

Using

P F 1 or P F 2 as secondary menu shortcuts: Enter the

menu and scroll to P F 1 or P F 2 . To switch to the secondary menu entries, tap

D I S P L A Y . (Tapping D I S P L A Y again will return to the

primary menu entries.) Select the desired parameter, then exit the menu.

P F 1 or P F 2 : Fast Play

B A N D + / B A N D - . To

Using a Separate Receive Antenna

The 160 m/RXANT option (K160RX) provides a separate receiving antenna. This capability is included with the 160–m option because such an antenna is frequently used on 160 meters. However, the receive antenna switch can be used on any band.

To enable the receive antenna: Switch to the desired band. Next, use the menu to change the R A N T option to O N . This will affect only the current band. If you anticipate switching between the normal and receive antennas often, you can program

P F 2 as R A N T .

P F 1 or

AGC On/Off Control

Some operators prefer to turn AGC off and use manual RF GAIN control under certain weak-signal conditions.

To turn off AGC: Hold both the simultaneously. Release the switches when you see O F F flashed on

the LCD. To remind you that AGC is off, the decimal point to the left of the mode indicator will flash slowly. Received signals will no longer affect the S-meter level. Turning the RF GAIN control counter-clockwise will increase the S-meter reading.

P R E / A T T and A G C switches

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98 ELECRAFT

Frequency Calibration Techniques

The VFO is only as accurate as the 4.000 MHz oscillator on the Control board, which is calibrated using C22. C22 can be fine-tuned using one of the following methods:

Using an External Counter or Ham-Band Receiver:

These methods are described in detail in Alignment, Part II (4 MHz Oscillator Calibration). After setting C22 using either

technique, you must re-run C A L P L L (with the counter probe on TP1). You'll also need to use C A L F I L (with the probe on TP2) to re-adjust each BFO setting, which will allow the K2 to store new, more accurate BFO frequency measurements.

Using a Calibrated Signal Source:

You can calibrate C22 using a signal generator, ham transmitter, or strong AM carrier such as WWV at 10 MHz. The K2’s receiver is used to zero-beat this signal to determine how far off the VFO is, then C22 is adjusted to compensate. Because of the way C A L

P L L works, you can only use a signal source that is at one of the lower band edges, e.g. 7000.00 or 10000.00 kHz. Here's the

procedure:

exit C A L P L L when "End" appears.

9. Move the counter probe to TP2 (BFO). Using C A L F I L ,

change the BFO control parameter for the filter presently being used by at least one count, then return it to the original setting. Tap

force the K2 to re-measure the BFO frequency.

10. Repeat step 2. If the VFO dial is still off, repeat steps 3 - 9.

11. Modify all BFO settings using C A L F I L (as in step 9).

M E N U to exit without switching filters. This will

Firmware Revision Numbers

You can check the K2's main microcontroller and I/O controller firmware revisions by holding in any switch on power-

up. Two numbers will then be displayed briefly. For example, you might see 2 . 0 3 A 2 . 0 4 . The first number is the main microcontroller's firmware revision and letter suffix. The second number is the I/O controller's firmware revision.

The ATU's firmware revision is one of the parameters in the ATU submenu, e.g. F 1 . 0 0 . This also applies to the KPA100. The SSB adapter's firmware revision can be obtained by first setting the S S B A menu entry to B A L , then holding the the S S B A menu entry to its normal setting after checking the firmware revision.)

V O X switch. (Return

1. Select LSB or USB mode on the K2.

2. Zero-beat the calibrated signal source on the K2, then note the

VFO dial error. For example, 10 MHz WWV might zero-beat at

10000.20 kHz. The error is then 10000.20 - 10000.00 = +0.20. Do not move the VFO from this position.

3. Connect the K2's internal counter to the VCO test point

(TP1).

4. Select and activate C A L F C T R using the menu.

5. Note the displayed VCO frequency. (In this example, 14913.88

kHz. Your VCO frequency will be somewhat different.)

6. Subtract the VFO dial error from the VCO to obtain a target

VCO frequency. (In our example, 14913.88 - 0.20 =

14913.68.)

7. Adjust C22 until the VCO is at the target frequency.

8. Re-run C A L P L L (see Calibration Functions). Tap

M E N U to

The firmware revisions for other options may also be accessible; refer to the individual option manuals.

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Resetting the Configuration to Factory Defaults

You should reset configuration data to defaults only if the K2’s EEPROM is accidentally corrupted. (This is extremely unlikely to happen.) The most likely symptom that this has occurred would be an unexpected frequency setting showing up on a particular band, or strange characters appearing on the LCD. Before resetting the configuration to defaults, try simply re-entering the correct frequency and storing it in the affected memory.

If you find it necessary to defaults, record the following data first:

• filter and BFO settings for all modes/filters (using CAL FIL)

• other CAL parameters, e.g. S-meter HI/LO, current limiting

• primary menu parameters

• secondary menu parameters, if applicable

To reset to defaults: Turn the K2 off, then hold down the and

6 switches, and turn power back on. The EEPROM will be

4 , 5 ,

rewritten with factory defaults. You can then re-enter the data saved above using the menu functions. Re-doing CAL PLL is also recommended.

Computer Control of the K2

If you have the RS232 interface adapter installed (model KIO2), or the 100-watt stage (KPA100), you’ll be able to use a computer to control the K2. Both the KIO2 and KPA100 provide true RS232 levels (at 4800 baud), with no need for a level converter.

The K2's computer-control capabilities are compatible with nearly all contesting, logging, and remote-control software, including Elecraft's k2remote and k2voice programs. Control over the internet is also possible. You can write your own programs as well (see the KIO2 Programmer's Reference, on our web site).

Refer to the KIO2 or KPA100 manuals for additional details.

Fine RIT Mode

The K2's FINE RIT feature provides receiver tuning in steps smaller than 10 Hz. The primary use of FINE RIT is for data modes such as PSK31, which can benefit from a reduction in T/R frequency shift between FL1 and one other filter

is only effective for this if FL1 is configured as O P 1 (SSB crystal filter). FINE RIT can also be used to accurately zero-beat AM

stations, or to fine-tune CW signals when a narrow filter is used.

Limitations: Entering FINE RIT mode turns off SPLIT, RIT, and XIT, which cannot be used in combination with FINE RIT. If you move the VFO while using FINE RIT, you may need to readjust the OFFSET control due to small differences in linearity over the VFO's tuning range.

To use FINE RIT: Select a narrow data-mode filter (F L 2 - F L 4 ) using

X F I L . Next, hold R I T and X F I L together; the display will

show F I N E O N , and the RIT and XIT annunciators will alternate on/off slowly. Only F L 1 and the selected narrow filter will now be available; the other two will be temporarily disabled. You can then use the OFFSET knob to fine-adjust the signal pitch of the narrow filter without affecting the pitch of FL1. Turning the OFFSET knob will display the filter selection and the FINE RIT offset, from

-15 to +15 units (e.g., F L 3 - 1 2 ). One unit is about 1 to 3 Hz (finer on lower bands). When you transmit (always through O P 1 ), you will be closer to the received station's carrier frequency, and on receive, switching filters will result in few if any lost characters.

To cancel FINE RIT: Hold

R I T + X F I L , or change modes or bands.

F I N E O F F will be displayed.

In data modes, the TX and RX frequency will always be exactly the same

if you use only FL1 (if set to O P 1 ), and avoid using splits. However, you may wish to switch to a narrow filter when QRM is present. The shift in

frequency between O P 1 (which is used on transmit) and the narrow filter can cause the signal to "walk" up or down the band if "net" is turned on in the demodulation software. Most software provides a means of turning off "net" (i.e. locking the TX frequency). FINE RIT provides a supplemental tool.

. FINE RIT mode