[AMRadio] Mod Transformer Available


Bob Bruhns bbruhns at erols.com
Wed Sep 28 00:54:29 EDT 2005


Looks like the Liberty Ships ran 200 watts after
all.  Interesting.  Article by a different Jim
Fisk:
http://www.arrl.org/news/features/1999/0216/2/?nc=1


----- Original Message ----- 
From: "Bob Bruhns" <bbruhns at erols.com>
To: "Discussion of AM Radio"
<amradio at mailman.qth.net>
Sent: Tuesday, September 27, 2005 10:36 PM
Subject: Re: [AMRadio] Mod Transformer Available


> 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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