Folks:
I am parting out a robust, home brew RF Deck that carried a pair of 4-400 A
tubes, very similar to a 3-500Z design. It was robustly built, and has a
huge silver Pi Net rotary Coil, Vac Variable Tune and Load,
heavy TX/ RX relay, 8 big sprague feed throughs, and a Mil Spec Filament
Transformer.
My question is about the Fil transformer, an old school completely sealed
metal case unit. Inscribed on the case are designators:
Grade 1 Class A Audio Device Company A8023 5252C 117V
Output has two ea 2.5V center tapped windings which are seriesed together,
with the middle terminal of the two in series, grounded, and the 5 volts
picked off the ends of the grounded, centertapped, serised windings.
The Current spec printed on the transformer case shows 23 Amp capacity
secondaries. A pair of 3-500Zs needs 30 amps to function. The amp worked
fine for decades, and I believe I actually measured 5.0. volts at the tube
pins in operation, a long time ago.
With a 23 amp design current capacity, how is it possible that the
transformer held up to 5.0 volts, with a 30 amp draw?
Are the Mil type transformers conservatively rated? Is this over loaded
transformer likely to "let the smoke out" some day? Perhaps, it can just
tolerate the losses of higher current draw, and the terminal voltage is
higher, because the applied line voltage is 125, instead of the 117 design
voltage. I never checked if the transformer case was extra hot, in
operations.
All the Best, 73,
Pat Barthelow aa6eg@hotmail.com
http://www.jamesburgdish.org
Subscribe: http://bambi.net/jamesburg.html
Jamesburg Earth Station Moon Bounce Team
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