Elecraft KPA100 Manual - Manual (Page 15)

15
Check the resistance across each RF choke using the lowest
resistance scale of your DMM. This will ensure that the chokes were not
damaged during soldering. All readings should be under 10 ohms.
Sort all of the diodes according to type. Use a magnifying glass if
necessary to positively identify glass diodes (1N4148 and 1N5711).
Install diodes D1-D8 (1N4148) on the bottom side of the board,
near the large cutout, but do not solder yet. Bend the leads very close to
the body to fit the given pad spacing. The banded end of each diode
(cathode) must be aligned with the band on its component outline.
Make sure D1-D8 are seated as far down on the PC board as
possible. Solder and trim the leads.
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When installing the diodes in the next step, save the trimmed
1N4007 leads in a small labeled bag for use as jumpers, etc., in later
steps.
Install the remaining diodes on the top side of the board. Start with
D17, at the lower left-hand corner near the small notch.
__ D17, 1N5711 __ D16, 1N5711
__ D10, 1N5404 __ D13, 1N5404
Note: D14, 12, and 11 are not all oriented in the same direction
__ D14, 1N4007
__ D12, 1N4007 __ D11, 1N4007
__ D9, SB530
Using the diode check scale on your DMM, test all of the diodes on
the board. (This will ensure that diodes have not been damaged during
installation.) First, touch the red (+) lead of the DMM to the anode (non-
banded end), and the black (-) lead to the cathode (banded end); the meter
should indicate a forward voltage in the range of 0.1 to 0.7 volts, varying
with diode type. Next, reverse the leads; the DMM should show an open-
circuit indication (flashing "3.000" or "0.000," etc.).
Near the "ELECRAFT" label, you’ll find a short jumper location,
identified by a ground symbol ( ). Use a saved 1N4007 diode lead to
make a 3/4" (19 mm) U-shaped wire for this jumper. Mount the jumper on
the top side of the board, with the top of the U-shape approx. 1/4" (6 mm)
above the board. Solder it from the bottom side.
Install the following capacitors on the bottom side of the PC board,
but do not solder yet. Capacitors must be seated as close to the board as
possible. About 1/16" (3 mm) of lead length may remain exposed.
Remove any U-shaped bends or folds using long-nose pliers.
Note: These capacitors are all .01 µF (103), with 0.1" lead spacing.
__ C99  __ C97  __ C98  __ C22
__ C74 __ C29 __ C13 __ C15
__ C17 __ C19 __ C21 __ C14
__ C16 __ C18 __ C20
Use a ruler to check the height of all capacitors just installed, as well
as C65 (near the front edge) and C75 (near the back edge). If any
capacitor body extends to 3/16" (4.5 mm) or more above the surface of
the board, fold it down toward the board. The capacitors should not touch
any adjacent pads.
Solder the capacitors from the top side. Use just enough solder to
fill the hole, since the leads will be flush-trimmed in the next step.
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Important: Relays K1-K12 will be installed on the top side of
the board, opposite capacitors C13-C22 and C29. This requires that the
capacitor leads and their surrounding solder filets be trimmed as close to
the PC board as possible.
Flush-trim the leads of C13-C22 and C29 on the top side of the
board. After trimming, the leads and surrounding solder filets should be
no more than 1/32" (0.8 mm) high.