Pozosta ELECRAFT-K2 User Manual

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F

BAND

RCL

BAND

STORE

MENU

EDIT

+

-

DISPLAY

+

RF/ALC

ANT 1/2

+

TUNE

NB

+

LEVEL

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E L E C R A F T

S1

5 9 +20 40

RF 3 5 7 10

KEYER

AF GAIN

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RF GAIN

K 2

NB ANT2 PRE ATT A B RIT XIT

T R A N S C E I V E R

0

RATE

LOCK

MODE

+

VOX

PRE/ATT

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SPOT

RIT XIT

+

PF1

-1

A=BA/B

1

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7

0

AGC

PF2

+1

2

SPLITREV

8

3

XFIL

AFILCW RV

MSG

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REC

ON

OFF

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

Copyright

Elecraft • www.elecraft.com P.O. Box 69 • Aptos, CA 95001-0069 [phone] • Fax: [phone]

 2003 Elecraft, LLC

All Rights Reserved

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)

03

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.

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, [e-mail].

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

[e-mail] for support and [e-mail]

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

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

to

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.

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

1

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

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

1

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);

2

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.

3

See Frequency Calibration Techniques (page ).

3

+/- 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.

6 ELECRAFT

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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

rd

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

4

9.5 V min for 5 watts out

10.0 V min for 7 watts out

3

-order intercept 0 to +7.5

nd

2

-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

6

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

5

+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

4

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)

5

Varies with band.

6

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

may be available

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.

RF

Control

Front
Panel

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.

ront Panel

1

Control Board

P1

F Board

J6

P1

Figure 3-3

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.

1

). 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."

10 ELECRAFT

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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

3

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

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

i

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.)

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.

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

i

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.

i

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.

i

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.

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.

i

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

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

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.

1

Figure 4-3

i

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.)

2

Use smooth
bend, not sharp

i

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.

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.

i

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.

i

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)

18 ELECRAFT

op side of
C Board

i

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.

3

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

P1

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.

i

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

ELECRAFT 19

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

i

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.

i

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.

i

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

20 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). 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

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

i

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

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)

i

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.

ELECRAFT 23

i

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

i

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

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.

i

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

1

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.

i

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.

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.

i

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

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.

i

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

Pad

Top Edge

(Bottom of PC Board)

CD

Figure 5-11

Figure 5-12

ELECRAFT 27

(

)

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

28 ELECRAFT

Front Panel Final Assembly

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

to protect the finish and labeling.

i

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.

i

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

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