Elecraft K2 Owner's Manual

E L E C R A F T K 2 T R A N S C E I V E R

RCL

BAND

STORE

EDIT

DISPLAYBAND

RF/ALC

ANT 1/2

TUNE

LEVEL

E L E C R A F T

5 9 +20 40

3 5

KEYER

AF GAIN

ALC

RF GAIN

POWER

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

CW RV

AGC

PF2

SPLITREV

XFIL

AFIL

MSG

REC

OFF

O W N E R’S M A N U A L

ELECRAFT

160-10 Meter

SSB/CW

Transceiver

Owner’s Manual

Revision I, March 29, 2012

 2012 Elecraft, LLC

Elecraft  www.elecraft.com P.O. Box 69  Aptos, CA 95001-0069 (831) 763-4211  Fax: (831) 763-4218

2 ELECRAFT

Table of Contents

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

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

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

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

5. FRONT PANEL BOARD ................................................................................................................................................................... 23

6. RF BOARD ........................................................................................................................................................................................ 34

7. FINAL ASSEMBLY ............................................................................................................................................................................ 81

8. OPERATION ...................................................................................................................................................................................... 84

9. CIRCUIT DETAILS .......................................................................................................................................................................... 110

10. OPTIONS ......................................................................................................................................................................................... 117

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)

Elecraft  www.elecraft.com P.O. Box 69  Aptos, CA 95001-0069 (831) 763-4211  Fax: (831) 763-4218

ELECRAFT

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  Digital or analog audio filter, each with real-time clock  Internal 2.9-Ah rechargeable battery  Programmable band decoder  High-Performance VHF and UHF transverters

For a complete description of available options, see page 117. 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 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

. Among the available materials

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.

4 ELECRAFT

Customer Service Information

Technical Assistance

You can send e-mail to support@elecraft.com quickly - typically the same day Monday through Friday. Telephone assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays only) at 831-763-4211. Please use e-mail rather than calling when possible since this gives us a written record of the details of your problem and allows us to handle a larger number of requests each day.

Repair / Alignment Service (We want to make sure

everyone succeeds!)

If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer unlimited email and phone support to get your kit running, so please try that route first as we can usually help you find the problem quickly.)

IMPORTANT: You must contact Elecraft before mailing your product to obtain authorization for the return, what address to ship it

to and current information on repair fees and turnaround times. (Frequently we can determine the cause of your problem and save you the trouble of shipping it back to us.) Our repair location is different from our factory location in Aptos. We will give you the address to ship your kit to at the time of repair authorization.

Packages shipped to Aptos without authorization will incur an additional shipping charge for reshipment from Aptos to our repair depot

To ship the unit, first seal it in a plastic bag to protect the finish. Use a sturdy packing carton with at least 3-in (8 cm) of foam or shredded paper on all sides. Seal the package with reinforced tape. (Neither Elecraft or the carrier will accept liability for damage due to improper packaging.)

and we will respond

Elecraft 1-Year Limited Warranty

This warranty is effective as of the date of first consumer purchase (or if shipped from the factory, the date the product is shipped to the customer). It covers both our kits and fully assembled products. For kits, before requesting warranty service, you should fully complete the assembly, carefully following all instructions in the manual.

Who is covered: This warranty covers the original owner of the Elecraft

product as disclosed to Elecraft at the time of order. Elecraft products transferred by the purchaser to a third party, either by sale, gift, or other method, who is not disclosed to Elecraft at the time of original order, are not covered by this warranty. If the Elecraft product is being bought indirectly for a third party, the third party’s name and address must be provided at time of order to ensure warranty coverage.

What is covered: During the first year after date of purchase, Elecraft will

replace defective or missing parts free of charge (post-paid). We will also correct any malfunction to kits or assembled units caused by defective parts and materials. Purchaser pays inbound shipping to us for warranty repair; we pay shipping to return the repaired equipment to you by UPS ground service or equivalent to the continental USA and Canada. For Alaska, Hawaii, and other destinations outside the U.S. and Canada, actual return shipping cost is paid by the owner.

What is not covered: This warranty does not cover correction of kit

assembly errors. It also does not cover misalignment; repair of damage caused by misuse, negligence, battery leakage or corrosion, 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.

ELECRAFT

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

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

2.0 A typical at 10 watts; programmable current limiting

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

VFO Stability < 100 Hz total drift typ. from

cold start at 25° C

Accuracy

+/- 30 Hz over a 500 kHz range

(typ) when calibrated

Resolution 10 Hz

Tuning steps 10 Hz, 50 Hz, and 1000 Hz nominal (other step sizes available via menu)

Memories 20 (10 assigned to 160-10 m Bands; 10 general-purpose)

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

10-40 Hz steps depending on range.

Fine RIT mode steps 2-3 Hz typ.

Frequency control PLL synthesizer w/single VCO covering 6.7-24 MHz in 10 bands; fine steps via DAC-tuned reference

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

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

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 105).

6 ELECRAFT

Transmitter

Power output range <0.5 W to >10 W (typ.); power setting resolution 0.1 W, accuracy 10% @ 5 W

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

10.0 V min for 7 watts out

10.5 V min for 10 watts out

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;

will survive operation

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

External keying 70 WPM max.

9.5 V min for 5 watts out

into high SWR

Receiver

Preamp On Preamp Off

Sensitivity (MDS) -135 dBm -130 dBm

Dynamic range,

I.F. 4.915 MHz (single conversion)

Audio output 1 watt max. into 4-ohm load

-order intercept 0 to +7.55 +10

-order intercept +70 +70

Blocking 125 dB 133 dB

Two-tone 96 97

Selectivity,

CW 7-pole variable-bandwidth crystal

filter, approx. 200-2000 Hz

7-pole fixed-bandwidth crystal

SSB

filter, 2.2 kHz typ.

Speaker internal: 4 ohm, 3 W;

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

chaining; auto-repeat (0 - 255 s)

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

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

Rear-panel jack for external speaker

Headphones 4 - 32 ohms, stereo or mono

Varies with band.

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

ELECRAFT

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

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

(Right side panel

not shown)

Figure 3-2

Figure 3-1

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.

Front Panel

Control Board

RF Board

Figure 3-3

ELECRAFT

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

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.

150 pF: These are correctly marked "151" on one side, but the other

side may be marked #21 ASD, where "#21" looks like "821."

). Similarly, "330" would be 33 pF,

10 ELECRAFT

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%)

Multiplie

Second Digit

First Digit

Color Multiplie Black 0 x 1

Brown 1 x 10 Red 2 Orange x 1K Yellow 4 x 10K Green 5x 100K Blue 6x 1M Violet 7 Gray 8 White 9

Silver -- x .01 Gold -- x 0.1

Digit

x 100

Figure 3-4

ELECRAFT

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.

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:

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. Bottom-mounted parts are identified on the schematic by this symbol:

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.)

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 anti-static 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.

ELECRAFT

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.

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 righthand 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.

during manufacturing. Remove the wrenches and wipe off the oil, if any, then discard the bag.

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 flat-head, 3/16" screw.

Flat-head, 3/16” (4.8 mm)

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)

The Allen wrenches are located in a small bag with the

MISCELLANEOUS items. These wrenches may have been oiled

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

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, 270 k (RED-VIO-YEL) __ 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.

Note: Save clipped leads from 1/4-watt resistors that are at least 1/2” (13 mm) long. You’ll need several of them for ground test points and other uses later on.

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.

Install the remaining resistor networks in the order listed 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)

Solder the resistor networks. (No need to trim the leads.)

Install potentiometer R1 (50 k), located at the left side of the board. R1 will sit above the board due to the shoulders on its pins. Hold it in place (flat, not tilted) while soldering.

ELECRAFT

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

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 1N4148 diodes listed below. D1 is in the upper lefthand corner of the PC board. 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

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

Find the component outline for diode D3, near the top edge of the

board (right end). Install and solder resistor R22 at this location (82 k, gray-red-orange).

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)

__ 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, .01 (103) __ 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.

16 ELECRAFT

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.

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.

Figure 4-2

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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.

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.

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.

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 4-3

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

end, not sharp

Figure 4-4

Solder the voltage regulator ICs.

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

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.

18 ELECRAFT

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

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).

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

Locking

Tab

Top side of PC Board

Figure 4-5

Install the 10-pin, dual-row connector, P4 (to the left of P5). The short ends of the 10 pins are inserted into the board. P4 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.

At the upper left and right corners of the board are short jumpers, labeled with ground symbols ( make 3/4" (19 mm) long U-shaped wires for each jumper (Figure 4-6). Solder the jumpers on the bottom of the board, with the top of the Ushape approx. 1/4" (6 mm) above the board.

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 and KDSP2 audio filter options. You should not install J1 and J2, or an audio filter option, until after K2 assembly and checkout have been completed.

Install short wire jumpers at R18 and R19. Make the jumpers from discarded component leads as you did above, but keep them flat against the board. Solder the jumpers on the top side.

Install the following resistors on the bottom side of the board (solder on the top side):

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

). Use discarded component leads to

Figure 4-6

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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

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.

The connectors along the bottom edge of the board (P1, P2

side of the Control board as shown.

Top side of PC Board

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

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.

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

20 ELECRAFT

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

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 DualInline 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.

Notch

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.

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

Pin 1

Dimple

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.

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.

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

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.

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Key Shaping Components (Required)

Your K2 kit includes recent changes that provide an optimized keying envelope shape (sigmoidal, or S-shaped leading and trailing edges). The result is completely click-free CW transmission. Two of the parts for this change must be installed on the back of the Control board as described below.

Locate the green insulated hookup wire. Strip two 1/4" (6.4 mm) lengths of insulation from one end of the wire. These will be used to insulate

the leads of C46 in the following steps.

Slip the two lengths of insulation over the leads of a .01 µf capacitor ("103"). This is a new component (C46), not present on the board.

Figure 4-11, below, shows the bottom side of the Control board. Components shown with dotted outlines are located on the top side.

On the bottom side of the Control board, solder C46 between R21 and the base lead of Q8 as shown below. Keep lead length short.

Figure 4-11

A 22 µF electrolytic capacitor has also been added (C45). Solder C45 as indicated above, between U8 pin 2 (+ lead) and U8 pin 14 (- lead).

Carefully compare your installation of C46 and C45 to Figure 4-11. Make sure the leads of these capacitors are soldered to the indicated pads.

Verify the orientation of the (+) and (-) leads on C45.

22 ELECRAFT

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 or KDSP2). An audio filter should not be installed until the K2 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. Note: Some digital multimeters will flash

their display to indicate an infinite resistance.

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. (to GND)

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

Q1 collector 8T > 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

ELECRAFT

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 liquid-crystal 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 righthand corner.

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.

SWITCH SPACINGTOOL

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.

S1 S2

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.

Figure 5-2

24 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 check-list 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 Use discarded component leads to make 3/4" (19 mm) long 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.

symbol.

ELECRAFT

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.

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

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

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

The bargraph LED will be installed in the following two 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.

Locate the bargraph LED, DS2. The bargraph has a beveled 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 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. Re-check the orientation of the polarizing nub before soldering.

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, re-heat the solder on the corner pins alternately while pressing it down. There may be small nubs on the back of the bargraph LED. If so do not remove them. Simply be sure all four nubs are against the PC board. Once it is in the correct position, solder the remaining pins.

Double check to ensure you have soldered ALL the pins on

the LED bargraph. Many builders miss pin 1.

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

Figure 5-5

26 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

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.

Install the audio-taper potentiometer, R3, in the lower left-hand

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

Figure 5-7

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.

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

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

ELECRAFT

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

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.

Position the backlight assembly between the mounting holes

labeled D2 and D3 as shown in Figures 5-9 and 5-10 with two 3/4" (19

mm) long spacers under each end. The diffuser must be parallel to and 1/8" (3 mm) above the PC board. Use a rubber band to hold the

backlight assembly and spacers in place.

diffuser

LED leads

spacers 2 under each end

pc board

(remove after solderin

LED leads)

Figure 5-9

diffuser

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.

Make sure the LEDs in the LCD backlight assembly are pressed into the diffuser and are not mis-aligned or loose.

Examine the backlight assembly closely to ensure that it is parallel to the Front Panel board and seated against the spacers (exactly 1/8" [3 mm] above the board).

Solder D2 and D3. If the backlight assembly is no longer flat against the PC board, re-heat the LED pins one at a time and press it into place.

LED

Figure 5-10

28 ELECRAFT

CAUTION: The LCD and its pins are fragile—handle

carefully. Do not drop the LCD on a hard surface, as it is made of glass and may break. 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.

LCD

Figure 5-11

Carefully remove the LCD from its packing materials.

CAUTION: Do not peel off the thick plastic material on either side of the LCD, or the LCD will have to be replaced (not covered under warranty).

Hold the LCD up to a bright light and look at both sides for the

presence of a very thin, clear protective film (like transparent tape). All LCDs have such film on the front surface of the LCD, which will be removed in a later step. But the back of some LCDs (not all) may also

have such film, with faintly visible yellow or gray diagonal lines. If protective film is found on the back side, use a fingernail at one corner of the LCD to dislodge it, then peel it away.

The LCD has six pins along its lower edge (three on each side), and 24 pins along the upper edge. Place the LCD in its proper position on the board but do not solder yet.

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 misaligned. When the assembly is installed correctly, the LCD’s pins will all protrude the same distance from the bottom of the board. The leads

may not extend through the solder pad holes.

Solder the four corner pins of the LCD, and 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. If the leads do not reach through the holes, be sure the solder fills the gap between the lead and solder pad (see Figure 5-9). After soldering, remove the spacers at each end. The leads will hold the assembly securely in place.

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.

Pad

Top Edge

(Bottom of PC Board)

Figure 5-12

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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. (to GND)

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

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Elecraft K2 Owner's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual