As a followup to my question about the grid bias supply on the G.E. Ham News
813 amp (and the B&W LPA-1 is nearly the same design):
The bias supplies for these amps use a 120:120 transformer, half-wave diode
rectifier, C/RC filter (40uF/500 ohms/40uF) and a 500-ohm, 25-w rheostat load
for the adjustable bias. These supplies are said to provide zereo to -100v
bias. Yet, the settings for CW and SSB only use -19 volts and -5 volts. Why
then, is it necessary to have -100 volts available? Seems like a much smaller
supply would suffice.
Thanks, Steve KK7UV
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