ELECRAFT 31
Turn the K1 off and disconnect the power supply.
Install the headphone jack, J2, on the small board extension
near the front-left corner. The pins on J2 are not very long, so
they will be nearly flush with the bottom of the board. Solder the
pin closest to the front edge first (ground), then verify that the
jack is seated flat on its plastic nubs before soldering the other pins.
Mono Headphones: If you plan to use only a mono plug at J2, cut
the trace marked "cut = mono" on the bottom of the board, under
J2. (You'll lose the sound on one side of stereo headphones.)
Install the key jack, J3, at the back-left corner. Before
soldering, make sure that the jack is aligned with its PC board
outline.
Install the antenna jack, J5 (BNC), in the back-right corner.
Solder one of the large ground mounting pins first. If J5 then
appears to be tilted or twisted, reheat this ground pin while pushing
J5 down onto the board. Once it is seated properly, solder the
remaining pins.
The internal speaker connector, P2, is a 2-pin connector with
a locking tab. Orient P2 as shown by its PC board outline, near the
front-right corner of the board, with the locking tab facing the
front. P2 must be seated flat against the board before soldering.
Install crystal X5, near the front edge of the board. Make sure
it is flat against the board and not tilted before soldering. (The leads
can be bent to hold it in place.)
Install X6 near the back-left corner.
Install X1-X4 at the front-right corner.
Ground the cases of all six crystals, using the near-by ground
pads. Use discarded component leads as before. Limit soldering time
to 4-5 seconds to avoid overheating the crystals.
Install R39 (1.8 k, BRN-GRAY-RED) on the bottom of the
board near crystal X6.
In the back right corner of the board near the antenna jack
(J5), install P3, a 3-pin male connector. The long end of P3's pins
face up.
Install the two-pin shorting jumper across pins 1 and 2 of P3
(the two terminals closest to J5).
On the bottom of the board, install R4 (5.6 k, GRN-BLUE-
RED).
Locate the miniature slide switch, S2. Install S2 on the bottom
of the board, with the switch pressed down onto the board as far as
it will go. (If it isn't pressed all the way down, the actuator might
hit the bottom panel.) Limit soldering time on each of S2's pins to
2 seconds to avoid melting the plastic body.
Set S2's actuator to the "OPER" (operate) position.
Locate the component outline for RFC8, on the bottom of
the RF board in the transmitter area. Install a short wire jumper at
RFC8, formed from a component lead or solid hookup wire.
Note: an RF choke may be supplied with the 80-meter band kit (2-
band Filter board only) for use at RFC8. This RF choke can be
installed at any time, and will have no effect on K1 alignment or
testing on any band. Its function is to improve stability on 80
meters when the K1 is used with poorly-matched loads or an ATU.
Locate the component outline for RF choke RFC9, on the
bottom of the board between the pins of relay K1. Flush-trim the
four pins of K1 closest to RFC9.
Form the leads of RFC9 (15 µH, BRN-GRN-BLK) to fit
between the indicated pads. Install RFC9 and position its leads so
that they don't contact any adjacent pads of K1. Solder and trim
RFC9's leads from the top side of the board.
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