[AMRadio] filament voltages

[W4AWM at aol.com]

It is only necessary to reduce filament voltage by a few tenths of a volt, 
which is not going to hurt anything.  The first thing you should do is check and 
monitor your power line voltage.  Mine varies during the day by +5 volts! A 
variac is the easiest way to control it but you have to be able to monitor the 
filament voltage constantly for it to be of any value.  Virtually all 
broadcast transmitters back in the tube days had filament voltage variacs and a meter 
to monitor the voltage, so it is important to know what is happening. Also 
back in the good old days, these and other operating parameters had to be logged 
every thrity minutes by FCC decree.  A great after school job for us up and 
coming hams.

73,

John,  W4AWM