harbach-electronics sk-220 User Manual

2

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Replace the perforated cover and top rear plate cover.  Reinstall the 15 sheet metal screws
holding these p ieces in place.  DO NOT over tighten these screws, as it is fairly easy to
strip the screw threads in the aluminum underneath.

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Use the  book to hold the am plifier while you reinstall the case and feet.

This completes the installation of the SK-220 “Soft K ey” module.  Y ou m ay not SEE any

difference in the operation of your exc iter or amplifier, but you will know that you have reduced the
stress on the exciter’s keying relay by many orders of magnitude.

Jeff Weinberg – W8CQ

468 County Road 620

Polk, OH  44866-9711

(419) 945-2359

R1 & R2

100K

Ω

 ½W  5%

R3

10K

Ω

 ¼W  5%

C1 & C2

0.1

µ

F 50VDC CERAMIC

D1

1N4005 (1A 600 PIV)

D2

1N60 GERMANIUM

Q1

MPS2222

Q2

IRF610 HEXFET (N-CHANNEL)