Re: RCA Modulation Transformers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

Those extra contacts could be a number of things:

A cathode or grid feedback winding to linearize the power amp

Ultra-Linear taps for use with pentode modulator tubes

A low-impedance winding for driving a loudspeaker (some mobile radio sets 
used on ships etc. could also be used as a PA)

Taps on the output winding for adjusting impedance matching

Etc

Why not measure them with a multimeter and see the DC resistance, what 
other windings they connect with, and so on, that will give you some more 
clues. You can do a complete identification of the transformer, and figure 
out what tube types, power, bandwidth etc. it will handle, using a 
multimeter, a signal generator, a scope, and a couple of test capacitors. 
I've done this before and can explain how if you're interested.

Steve C.

At 15:49 25/05/03 -0600, you wrote:
>Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><dhmccauley-at-spacecatlighting-dot-com>
>
>I just acquired a nice large RCA modulation transformer which I plan to use
>to modulate my plate voltage on my dual 833A
>VTTC for audio modulation.
>
>The input side of the transformer has the one center-tapped winding which
>the audio modulated push-pull tube circuit is fed into.
>The output winding is where the plate voltage (now modulated) would wire in
>series with.
>
>However, there are three additional contacts (possibly another center-tapped
>winding) on the same side of the output side but smaller in
>size than the output modulated winding.
>
>Anyone have an idea of what this winding was for???  This thing must be 70
>years old at least, so I'm very doubtful any datasheets could be found on
>this thing.
>
>Thanks
>
>The Captain
>