Elecraft K2 Owner's Manual User Manual

Page 52

LECRAFT

Locate all of the small glass-bodied diodes. You should have a

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

Install the following diodes, located near the outline for toroidal

transformer T5, in the synthesizer area. Be sure to orient the diodes
according to their outlines.

__ D11, 1N4148

__ D13, 1N4148

__ D6, 1N4007

__ D7, 1N4007

Varactor diodes have a small plastic package, like a TO-92

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

Install the MV209 diodes listed below. The flat side of each diode

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

__ D16

__ D23

__ D24

__ D25

__ D26

__ D39

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

Install type 1SV149 diodes at D37 and D38, near the SSB option

connector. Keep them flat against the PC board, with no excess lead
length.

Install the remaining 1SV149 diodes listed below, keeping them

flat against the PC board, with no excess lead length. D17, D21 and
D22 are in the front-left corner. D29 through D34 are on the right side
near the crystal filter.

__ D17

__ D21

__ D22

__ D29

__ D30

__ D31

__ D32

__ D33

__ D34

Install the TO-92 package transistors listed below. Start with Q17,

near the middle-left edge.

__ Q17, 2N7000

__ Q16, PN2222A

__ Q18, J310

__ Q19, J310

__ Q20, 2N7000

__ Q24, J310

__ Q25, PN2222A

Install Q21 (2N5109), which is located near U1 in the middle of

the board. Align the small tab on the transistor’s case with the tab on
its component outline. Bend the leads on the bottom to hold Q21 in
place, then solder.

Install Q22 (2N5109), which is to the right of the "ELECRAFT"

label. Make sure Q22 is flat against the board before soldering.

Carefully press a 3/4" (19 mm) dia. by 0.25" (6.4 mm) high star

heat sink onto Q22. The heat sink should be pressed down as far as it
will go, and should not touch the components around the transistor.
The heat sink is fragile. If you need to spread it slightly, use a
blunted wooden pencil or a plastic wire nut.

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

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

Install C167 (.001 µF, "102"), which is near J11, the connector for

the SSB adapter. The leads on this capacitor should be formed to
match its PC board outline.