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echo: ham-sale
to: IVY IVERSON
from: JEFF EDMONSON
date: 1997-08-16 16:40:00
subject: transformer

z> JE> Looking for a 7.5v @ 12Amp transformer.
z> JE> Anyone?
z>
z>That's an oddball.  What's it for?
Filaments for a Eitle McCullogh 450TL (Eimac).
The BC-610 used to use a singe 250TH in the final, modulated by a pair of 
100TH's.
Here, I'm going to be using a pair of 250TH's, modulated by a pair of 
0TL's.
(Difference between a TH and a TL, is the High inductance, or Hi-mu, vs. Low 
inductance, or low-mu.  The low-mu tubes needing more drive, naturally)
I'll feed 'em about 2500v, drive their grids with an emitter-follower circuit 
as a solid state descrete audio driver, that's fed from the condensor 
by-passed plates of a push-pull output speech amplifier.
I've got a pair of transformers here, now - the secondary is 6.6v, which 
compared to 7.5v isn't enough to worry about.  It'll keep the tubes working 
longer, in fact!
besides, they measure out to around 7v, even after being lit-up!
Thanks for the suggestion, though!  The technical info would be best shared 
in the HAM_TECH echo! (hint hint ;-> )
73 = Best Regards,
-Jeff KA5THB
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