[Heathkit] Heathkit HW/SB transceiver mod for greater audio output.

[Kenneth G. Gordon]

This mod increases the audio output in the receive condition. 
Most original transceivers need to have the audio gain pot set 
at 10 or 11, i.e. nearly all the way up,  for enough audio output. 
This mod will enable the operator to set the audio gain pot to 2 
or 3 for the same amount of audio output, plus have the ability 
to raise it much higher in low noise, weak signal conditions.

1) Find C-928, a .05 mfd tubular capacitor under the BOTTOM 
of the audio circuit board. One end of this capacitor is connected 
to pin 7 of V-14B the 6GW8 audio output tube, and  the other 
end is connected to one of the output terminals of T-301, the 
audio output transformer.

2) Remove this capacitor.

Capacitor C-928 provides a considerable amount of negative 
feedback to the audio stage. This reduces audio distortion at 
high volume levels, but also severely limits the maximum audio 
output of the stage. For most amateur radio users, this lower 
value of distortion is not important. In any case, .05 mfd is too 
large. If you find the distortion to be objectionable (I didn't, 
even for phone patching), you can experiment with lower values 
for C-928 to arrive at an acceptable compromise of distortion vs 
audio output.

Doing this mod will also reduce the temperature of the audio 
output tube.

Ken W7EKB