[AMPS] Collins 30S1 Improvements

[Phil Clements]

This is not my mod...it was published years ago by my friend John Adel, W5RR.

  
Readjusting the bias and tuning meter calibration after raising screen
voltage to
300v:

Turn the bias adjust control fully counter-clockwise. Energize the 30S1,
operate
the control relay in the exciter (PTT) but with gain control at minimum..no
power
out from exciter. Then hold interlock button in, press ON button and adjust
bias
adjust control so that the plate meter reads 100-150ma with zero signal.
Some tubes
or bias supplies will not allow the resting current to go above 100ma...no
problem.

If you want to calibrate the tuning meter:
Put the 30S1 on a dummy load. Band switch to 14 mhz. Tune and load until
power output
reaches 200 watts. The tuning knob should be turned so that maximum LEFT
deflections
occur regardless of being off zero. Now increase the output to 800 watts,
dipping
the tuning control and adjusting the loading control so that the plate
meter reads
420 ma for an output of 800 watts. Push the OFF button to remove plate
voltage,
open top cover and block down the interlock button. Energize by pushing the
ON button
(caution...3000v now exposed to the world!) recheck that the output is
still 800 watts
the plate meter reads 420 ma and the tuning control dips to a maximum left
deflection.
Adjust ceramic variable capacitor C-112 (see photo #7 in your manual) with an
insulated screwdriver so that the reading on the tuning meter is brought to
zero.
Put everything back together. The ratio of impedance matching is now
correct for the
new values of screen and bias voltages. Tuning can now be done according to
the
instructions in your manual.

(((73)))
Phil, K5PC

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