[AMRadio] filament voltages


Geoff/W5OMR w5omr at w5omr.shacknet.nu
Mon Aug 16 17:43:59 EDT 2004



> 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.

I think the recent home-brewed modulator built (mostly) by WA5BXO does a
pretty good job, at that.

The meters, across the top are      Ip     Bias Voltage       Filament Voltage

http://w5omr.shacknet.nu/~w5omr/hamstuff/AM-Stuff/Titanic/modulator/

73 = Best Regards,
-Geoff/W5OMR





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