User Guide
1
SK-201 “SOFT KEY” INSTALLATION INSTRUCTIONS
PARTS SUPPLIED WITH THIS KIT:
(1) SK-201 “Soft Key” Circuit Board Assembly
(1) Nylon Threaded Spacer
(2) 6-32 x ¼” Screws
(1) 2-Lug Terminal Strip
(1) #6 Lock Washer
To start the installation, read these instructions very carefully. Unplug the amplifier and
remove any input, output and control cables that may be connected to the back of the amplifier.
Remove the chassis from the case and remove the perforated sheet metal RF shield from the top
of the chassis. Remove the tubes and put them in a safe place. You are now ready to proceed
with the installation.
( ) Turn the amplifier over so that the rear is toward you. Locate a point that is 8” from the
right edge of the chassis and 4½” from the rear of the chassis. Mark this point.
( ) Very carefully drill a hole that will clear a 6-32 screw at the point you just marked (#27 drill).
Do not use too much pressure because you want the drill to stop after just penetrating the
chassis. Clean up any burrs from the hole.
( ) Rotate the chassis so that it is on its side with the transformer down (it is more stable that
way). Push (1) 6-32 screws through the hole from the tube side of the chassis. Put on a
lock washer and attach the nylon spacer onto the screw (on the underside of the chassis
and tighten.
( ) Inside the tube compartment, locate the screw that fastens the RF shield to the chassis and
secures terminal strip “Q” to the underside of the chassis. Terminal strip “Q” is a 5-lug
strip mounted at a right angle to the rear of the chassis. Loosen this screw and remove the
nut while keeping the screw through the chassis.
( ) Place the hold down lug of the supplied 2-lug terminal strip over the end of the 6-32 screw
(the one you just removed the nut from). It may require some adjustment of the wiring
harness to make room for the strip. The strip should be oriented approximately parallel with
the existing terminal strip “Q”.
( ) Reinstall the 6-32 nut onto the screw and tighten. Now turn the amplifier over (bottom up).
( ) Locate the 33Ω 1W resistor going from the antenna relay jack on the rear panel to a solder
lug at the end of the primary voltage selection strip. Unsolder the resistor from the jack and
move the end so that it goes through the insulated terminal on the 2-lug terminal strip you
just installed. DO NOT solder yet. Leave the 0.02µF disc capacitor connected to the
antenna relay jack.
( ) Install the SK-201 circuit board on the nylon spacer with a 6-32 x ¼” screw. Orient the
circuit board with the long side parallel with the rear of the chassis and the TO-220
transistor away from the rear of the chassis.