[AMRadio] Mod Transformer Available


Bob Bruhns bbruhns at erols.com
Tue Sep 27 22:36:58 EDT 2005


Man, those numbers -do- seem wierd.  5500 ohms and 200 ma add up to 1100V B+ and 220 watts DC input.  Not real good for a 1KW
transformer.

Maybe the transformer is a compromise design that can handle a little over a KW of audio with no unbalanced DC in the windings, but
can tolerate up to 200 mA of DC in the secondary and operate at reduced ratings if the user wants to use it that way.

How much power did the Liberty Ship transmitters run?  Did they use a modulation inductor, or did they run 220 watts, or did they
just run the core saturated, and blast out the MCW?  I think the issue of core saturation would have been less severe at several
hundred Hertz.

  Bacon, WA3WDR


----- Original Message ----- 
From: "James M. Walker" <chejmw at acsu.buffalo.edu>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Tuesday, September 27, 2005 9:59 PM
Subject: Re: [AMRadio] Mod Transformer Available


> Well,
> I guess I am still confused, Sigh but I am going to drop the request
> clarification, as the clarification seems to be muddled!
> Jim
> WB2FCN
>
>
> Donald Chester wrote:
> >
> > >
> > >The ratings are 5500 primary 1.14 KVA, and 5500 secondary
> > >198 Amp DC.
> > >
> > >Don,
> > >I don't know what you mean by don't add up! The discussion
> > >was pertaining to the use of this particular transformer, in
> > >conjunction with a specific set of tubes, and RF stage.
> > >What doesn't add up?
> >
> > The stated ratings of the transformer.  1.14 kva means it is rated for about
> > a kw of audio (theoretically 1140 watts with perfert power factor)  just
> > call it a kw to account for some inevitable phase shift.  That means it
> > should be designed to modulate 2 kw DC input.  But with the current rating
> > of .198 amps, to get 2 kw DC input, you would need 10,101 volts on the
> > plate.  The rated load impedance is 5500&#937;.  10 kv @ 198 mills is
> > 51,152&#937;
> >
> > Don K4KYV
> >
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