Elecraft K2 Owner's Manual - Manual (Page 51)

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LECRAFT ®
Locate the PLL Upgrade kit, which should include the
Thermistor PC board and all other parts listed below.
Ref Description Qty
RA 33K 1/4W Resistor (org-org-org) 1
RB 12K 1/8W Resistor (brn-red-org) 1
RC 2.2K 1/8W Resistor (red-red-red) 1
RD 1.8K 1/8W Resistor (brn-gray-red) 1
RE, RF 10K 1/8W Resistor (brn-blk-org) 2
THM Thermistor, 10K, 3% (small orange body
with black and brown stripes near leads) 1
MISC Thermistor PC Board 1
MISC #24 Green Wire, Insulated, solid conductor 1 ft.
(30 cm)
Locate the thermistor printed circuit board. One side will be
labeled with THM and the letters A through F. All components will
be installed on the labeled side, and soldered on the other side.
Install 1/8th-watt resistors RB, RC, RD, RE, and RF in their
respective positions as shown on the board. (Color codes are listed
above; be sure to check them carefully.) Do not pull on the resistor
leads, as they may be fragile. Bend the leads outward.
Solder all of the leads. Trim off excess lead length.
Install resistor RA (33 k, 1/4 watt). Solder and trim its leads.
Locate the thermistor, which has an orange body with black and
brown stripes. The thermistor is fragile, so avoid bending its leads any
more than necessary. Insert the thermistor at THM. (The part is
symmetrical and can be installed in either orientation.) Hold the
thermistor body so that it is just touching the circuit board, then solder
and trim its leads.
Remove the insulation from a 6” (15 cm) length of green hookup
wire. Cut the bare wire into 8 pieces of about 0.75” (2 cm) in length.
The remaining 8 holes on one edge of the board are used as leads
to insert into the pads provided for the original resistor network, RP3.
Solder one wire into each of the holes, with most of the lead
protruding from the component side.
On the component side, bend each lead at a 90-degree angle so
that it points away from the board (but parallel to it).
Locate the position for resistor network RP3 (near the front-left
corner, adjacent to U6). Slide each of the 8 leads of the thermistor
board through the corresponding holes at RP3. The components on the
thermistor board should be facing U6, and the thermistor should be
oriented toward the location of crystal X1. (See Figure 6-14a.)
Figure 6-14a
Once all of the leads are inserted, slide the board down until it is
flush against the RF Board. It may be necessary to bend the thermistor
board toward U6 slightly so that the solder joints on the bottom of the
thermistor board can clear C87 on the RF board. The thermistor board
and its parts should not be touching U6 or its pads.
Make sure the edge of the thermistor board is contacting the RF
Board along its full length. Then solder the eight connections on the
bottom side of the RF Board.
Examine the area closely. There should be no shorts between the
thermistor board and nearby components.