ELECRAFT K2 User manual

Elecraft •www.elecraft.com P.O. Box 69 •Aptos, CA 95001-0069 [phone] •Fax: [phone]
EL E C R A F T K 2
160-10 Meter
SSB/CW
Transceiver
Owner’s Manual
Revision C, April 19, 2000
Copyright 1999-2000 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. MODIFICATIONS............................................................................................................................................................................. 100
10. THEORY OF OPERATION............................................................................................................................................................. 101
11. INTERNAL OPTIONS...................................................................................................................................................................... 108
PARTS LIST.............................................................................................................................................................................APPENDIX A
SCHEMATIC.............................................................................................................................................................................APPENDIX B
BLOCK DIAGRAM..................................................................................................................................................................APPENDIX C
PHOTOGRAPHS.....................................................................................................................................................................APPENDIX D
TROUBLESHOOTING............................................................................................................................................................APPENDIX E
PARTS PLACEMENT DRAWINGS....................................................................................................................................... APPENDIX F

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 K2 is also the first transceiver to offer
these features in kit form.
The basic K2 operates on 80-10 meter CW, with adjustable power
output from 0.1 to over 10 watts. You can also customize your
K2 by choosing from a wide range of internal options:
!SSB adapter
!160-m module with receive antenna switch
!Noise blanker
!Automatic antenna tuner
!2.9-Ah rechargeable battery
Additional options are planned (see page 108). Also, 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-to-advanced 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 user interface (UI) 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, and
frequency counter. These circuits are completed early in assembly, so
the functions are ready to be used when you begin construction and
alignment of the RF board. We also provide complete
troubleshooting information, including detailed signal tracing
procedures for both receiver and transmitter.
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

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 the Elecraft e-mail forum, [email protected].
Telephone assistance is available from 9 A.M. to 5 P.M. Pacific
time (weekdays only) at 831-662-8345. You can also send e-mail
to [email protected]. Please use e-mail, rather than call,
when possible since this gives us a written record of the details of
your problem.
Repair Service
If necessary, you may return your completed kit to us for repair.
Contact Elecraft before mailing your kit to obtain current
information on repair fees. (Kits that have been soldered using
acid core solder, water-soluble flux solder, or other corrosive or
conductive fluxes or solvents cannot be accepted for repair.)
The following information should be provided to expedite repair:
your name, address, and phone number; your e-mail address (if
applicable); and a complete description of the problem.
Shipping: First, seal the unit in a plastic bag to protect the finish
from dust and abrasion. Use a sturdy packing carton with 3" or
more of foam or shredded paper on all sides. Seal the package with
reinforced tape. (Neither Elecraft nor the carrier will accept
liability for damage due to improper packaging.) Cover the "to"
address label with clear tape. Ship the equipment to:
Elecraft
8050 Soquel Drive, Suite D
Aptos, California 95003
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
2. Specifications
All measurements were made using a 14.0 V supply and 50-ohm
load at the antenna. Numeric values are typical; your results will be
somewhat different. Specifications are subject to change without
notice.
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 100-150 mA in minimum-current
configuration; 150-250 mA typical
Transmit12.0 A typical at 10 watts;
programmable current limiting
Frequency control PLL synthesizer w/single VCO
covering 6.7-24 MHz in 9 bands;
fine steps via DAC-tuned reference
1Current varies with band, supply voltage, configuration, and load
impedance. We recommend a minimum 3.5-amp power supply.
Frequency ranges,2MHz
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
(No transmit, 26.000-27.999)
160 m (opt.) 1.8-2.0
VFO
Stability < 100 Hz total drift typ. from
cold start at 25°C
Accuracy3+/- 30 Hz over a 500 kHz range
(typ) when calibrated
Resolution 10 Hz
Tuning steps 10 Hz, 50 Hz, and 1000 Hz
Memories 20 (10 assigned to 160-10 m
Bands; 10 general-purpose)
RIT/XIT range +/- 0.6 or +/- 1.2 kHz (selectable);
10 Hz steps
2The K2 can receive well outside the ham bands, but this extended range is
not specified or guaranteed
3See Frequency Calibration Techniques (Operation section, under Advanced
Operating Features).

6 ELECRAFT
Transmitter
Power output <0.5 W to >10 W (typ.);
power setting resolution 0.1 W,
accuracy 10% @ 5 W
Duty cycle 5 W, 100%; 10 W, 50%
Spurious products -40 dB or better @ 10 W (-50typ)
Harmonic content -45 dB or better @ 10 W (-55typ)
Load tolerance 2:1 or better SWR recommended;
will survive operation
into high SWR
T-R delay approx. 10 ms-2.5 sec, adjustable
External keying 70 WPM max.
CW sidetone 400-800 Hz, programmable in
10 Hz steps
CW T-R offset 400-800 Hz (tracks sidetone pitch)
Keyer
Keying modes Iambic A and B
Speed range 9 - 50 WPM
Message memory 9 buffers of 153 bytes each
Message handling 1-level chaining;
auto-repeat (0 - 255 s interval)
Receiver
Preamp On Preamp Off
Sensitivity (MDS) -135 dBm -130 dBm
3rd-order intercept 0 to +7.54+10
2nd-order intercept +70 +70
Dynamic range,
Blocking 125 dB 133 dB
Two-tone 96 97
I.F. 4.915 MHz (single conversion)
Selectivity,
CW 7-pole variable-bandwidth crystal
filter, approx. 200-2000 Hz
SSB57-pole fixed-bandwidth crystal
filter, 2.2 kHz typ.
Audio output 1 watt max. into 4-ohm load
Speaker internal: 4 ohm, 3 W;
Rear-panel jack for external speaker
Headphones 4 - 32 ohms, stereo or mono
4Varies with band.
5With 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.)
Top Cover
Front
Panel
Side
Panel
Bottom
Cover
Heat
Sink
(Right side panel
not shown)
Figure 3-1
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.
RF
Front
Panel
Control
Figure 3-2

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.
J
1
P1
J6
P1
F
ront Panel
R
F Board
Control Board
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 bag
!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 (inside the manual back cover) containing the LCD
bezel, green LED bargraph filter, serial number label, thermal
insulators, and two very small self-adhesive rubber pads (round
or square)
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 101). Similarly, "330"
would be 33 pF, and "102" would be 1000 pF (or .001 µF). All small
capacitors whose markings do not follow this convention are
described more specifically in the text and parts list.
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 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 is marked #21 ASD, where "#21" may look like "821."

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
Tolerance
(gold = 5%,
silver = 10%)
Multiplier
Second Digit
First Digit
Color MultiplierDigit
Black 0 x 1
Brown 1 x 10
Red 2
3
x 100
Orange x 1K
Yellow 4 x 10K
Green 5 x 100K
Blue 6 x 1M
Violet 7
Gray 8
White 9
Color Code
Silver -- x .01
Gold -- x 0.1
Figure 3-4

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)
!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. Older analog instruments may load down high-
impedance circuitry, making measurements less accurate.
!Magnifying glass
!Conductive wrist strap
Assembly Notes
iThis 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
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/or a vacuum desoldering tool. It also takes some practice.
A number of suggestions are provided 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.
!If you use a vacuum desoldering tool (solder sucker), use a large
unit. Small solder suckers are not as effective.
!With ICs, clip all of the pins at the body of the device first,
then remove all of the pins individually. 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.

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 microprocessor, analog
and digital control circuits, automatic gain control (AGC), and audio
amplifier are located on this board.
Components
iReview 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
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.
iThe 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.
iThere 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, 1/2” (12.7 mm)
Pan-head, 7/16” (11 mm)
Identify all of the 4-40 screws and sort them into groups.

14 ELECRAFT
Assembly
All of the components to be installed are on the top (component
side) of the control board. On the bottom of the board there is an
outline for the audio filter option and its two connectors (J1/J2).
With the top side of the PC board facing you (notch at the
lower left), locate the position of resistor R1, near the upper-left
corner. The label "R1" appears just below the resistor’s outline.
Install a 51-k resistor (green-brown-orange) at R1, with its
first color band (green) at the top. 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 the 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, 470 (YEL-VIO-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.
Note: Whenever you see an instruction to solder one or
more components with long leads (such as resistors), you
should trim the leads after soldering.
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. (RP6 may be labeled "10 K" on the
PC board rather than "5.1 K".)
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.
iComponents 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 all of the resistor networks.
Install short wire jumpers at R18 and R19, to the right of P2.
Discarded component leads (from resistors, large diodes, etc.)
should be used to form these and other short jumpers. Solder.

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, .001 (102)
__ C5, .01 (103) __ C14, .047 (473) __ C17, .01 (103)
__ C42, .01 (103)
__ C11, .01 (103) __ C16, .047 (473) __ C18, .01 (103)
__ C19, .047 (473) __ C21, 33 (33) __ C20, .001 (102)
__ C23, .01 (103) __ 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.
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.
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.
iGrounding 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.
X
1
X
2
Figure 4-3
iThe 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.), bending the leads as indicated (Figure 4-4). Use long-nose
pliers to create gradual rather than sharp bends. After inserting the
leads into the proper holes, secure each IC with a 4-40 x 3/8" (9.5
mm) machine screw, #4 lock washer, and 4-40 nut. (These
regulators may have either plastic or metal mounting tabs.)
Use smooth
bend, not 90°
Figure 4-4
Solder the voltage regulator ICs.
Trim the leads of these ICs as close to the PC board as
possible.

ELECRAFT 17
Install a 40-pin IC socket at U6. (The microprocessor 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.
iThe 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
T
op side of
P
C Board
Figure 4-5
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 S1, the miniature slide switch, to the right of P5.
At the upper left and right corners of the board you’ll find two
short jumper locations, each labeled with a ground symbol ( ).
These jumpers are provided for connecting clip leads during
alignment and test. Use discarded 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

18 ELECRAFT
iIn the following steps, the three multi-pin connectors
along the bottom edge of the board (P1, P2 and P3) will be
installed. These connectors must be positioned and soldered
carefully. Incorrect alignment of these connectors may cause
instability or intermittent operation, and it is very difficult to
remove them once they are soldered.
Position 6-pin right-angle connector P1 as shown in the side
view below (Figure 4-7). Also review Figure 3-3, which shows the
locations of all board-to-board connectors. 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 closely. 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 leads.
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.
T
op side of
P
C Board
P
3
Figure 4-8
Install P2, the 36-pin, dual-row, right-angle connector. Use the
same method you used for P1 and P3.
iWhen 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.
Straight
Flared
Figure 4-9

ELECRAFT 19
iBefore 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.
Pin 1
Notch
Pin 1
D
imple
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.
iYou 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.
Bend two of U2’s corner pins out slightly on the bottom of
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.
__ 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 microprocessor, U6.
Straighten the pins of the microcontroller, U6 (see Figure 4-9).
With large IC such as this, you can hold the IC body at the ends as
you re-form each row of pins.
iWhen 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.

20 ELECRAFT
Option Components
All component locations on the Control board should now be filled
except J1 and J2, on the bottom of the board, which 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
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.
(
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 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