[AMRadio] Mod Transformer Available

Donald Chester k4kyv at hotmail.com
Mon Sep 26 15:22:31 EDT 2005

>     I have a 1940s vintage 500 watt modulation transformer made by RCA for
>sale.  It has 5700 (approx.) ohm P-P primary and a 5700 ohm secondary.  I
>would like $250 plus shipping.  Local  pickup near Philadelphia preferred.
>I checked the windings and they have continuity.  There is also another
>winding of a higher impedance maybe for screens.  If interested please
>contact me directly at dogfaces at comcast.net

After WW2 those transformers flooded the market as surplus.  You could 
hardly attend a hamfest without seeing at least one.

They are not broadcast quality, but the quality is probably at least as good 
as typical trarsformers sold for ham radio use.

For years I wondered what they came from or what they were manufactured to 
go into.  A couple of years ago I found out that they were not used in phone 
transmitters at all, but in tone modulated CW rigs on board Liberty Ships 
during the war.  So they were desgined to pass only a single tone modulating 
frequency, but they work passibly for voice.  I would still prefer a 
transformer designed for voice use, preferably something from a broadcast 

Don k4kyv

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