[Amps] Utilization of old TV transformer

[Carl]

You might be pushing the insulation rating by more than a hair in either 
configuration, especially at the unused CT depending on how it is run 
internally. A hi-pot will tell you all the specifics.

This sounds like an ideal xfmr for a FWB and a couple of 4D22 or 4D32's at 
an easy 250W out; they run just fine with 750V and just a tad of air.

Carl
KM1H



>I have an old TV power transformer that I am thinking about using as a 
>plate transformer
> for a medium-power amplifier (2 x 813).
>
> It weighs between 15 and 20 pounds and the stack is 3.25" x 4.5" x 4".
>
> It has a hv winding for 680v at 290 ma and four filament windings which I 
> wouldn't use.
> The total VA output of all the windings is 313. But remember this rating 
> assumes
> continuous duty.
>
> The amplifier will be used on CW, so the duty cycle will be about 50%. I 
> would need to use
> either a doubler or tripler circuit to get a reasonable voltage for the 
> 813's.
>
> My guess is that a doubler would give me about 1900v which would probably 
> drop to about
> 1700 under load. If the 813's were loaded to 400 ma that would be 680 
> watts input.
>
> With a tripler I could get 2800v which would probably drop to 2400. At 360 
> ma plate
> current that gives me 864 watts input.
>
> My feeling is that the transformer would be OK with the first 
> configuration, but the
> second would be too much for it.
>
> Do you agree? Or should I forget about using this transformer and look for 
> a better fit?
> The fact that it's free is a big incentive.
> -- 
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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