Elecraft KRX3 User Manual download pdf (Page 53)

A-6

CAUTION

1) Do not use screws longer than 1/4” (6.4 mm) to mount the filters. Longer screws may

extend into the optional 8-pole filter and destroy it. We strongly recommend you use a 1/4”

screw even when installing the 5-pole filters to reduce the possibility of damaging an 8-pole

filter should you change them later.

2) Do not over-tighten the screws. Too much torque may pull the threaded bushing out of the

bottom of the filter module.

Figure A-6. Installing the Crystal Filters.

Double-check to ensure you installed each filter in the location you noted in Table 1. If you make a

mistake recording the data or installing the filters and miss it now, you’ll need to disassemble the KRX3

again to correct it.

Important: Do not over-tighten screws during reassembly. The screws should be tightened so that

the lock washers are fully compressed but never as tight as you can make them.

In the bottom half of the enclosure, check to ensure the four standoffs are tight against the enclosure. If

not, tighten the screws. Two are short standoffs for the board mounting screws and two standoffs have the

long screws threaded through them.

Place the KRX3 RF board in the bottom shield so that the long screws extend through holes shown in Figure

A-5. Press the circuit board down against the standoffs. The board may “snap” into position as the small bumps

along the edges of the board slip into the holes in the sides of the shield. When properly positioned, the board will

be against the standoffs in the bottom half of the enclosure. If needed, press down gently on the board near the

long screws to ensure it is not caught on the threads.

Secure the KRX3 main circuit board to the short standoffs at locations

in Figure A-5 with the 4-40 3/16”

(4.8 mm) black pan head screws and #4 split lock washers you removed earlier. Do not use inside tooth lock

washers.

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Elecraft KRX3 User Manual Page 53