[AMRadio] Transformers Revised

Rick Brashear rickbras at airmail.net
Mon Feb 19 10:19:08 EST 2007

Thanks, Geoff.  That may very well be the key to this problem.  The 
filament transformer I need is a 100 vac primary (or multi tap as you 
suggested) with a 5 vac @ 2.5 amp secondary.  This is out of a GE 
BT-20-A  broadcast transmitter and they used a small potted GE 
transformer.  I seems they were trying to insure you use their product 
for replacement.  There are five filament transformers and all have 100 
vac primaries that are wired in parallel through a large rheostat.  So, 
to make sure the filament voltage on all tubes is correct you adjust the 
rheostat to 100 vac as indicted on the filament voltage meter.  I assume 
they were insuring a perfect voltage match for even very low line 

The plate transformer I need is a standard frame type with 115 vac 
primary and 900-0-900 (1800 total) secondary.  I am guesstimating the 
current at around 300 ma.  It's the low voltage supply for the modulator 

Any help will sure be appreciated.


ARS W5OMR wrote:

> I've seen a lot of filament transformers that had 0 - 100 - 105 - 110
> taps on the primary, with one secondary.  They're out there, Rick.
> What voltages do you need?  I might have one.

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