[ARC5] Using a power transformers as a modulation transformer.

Glen Zook gzook at yahoo.com
Fri Apr 12 20:06:57 EDT 2013


Don't know about the link!  However, I have used power transformers from tube type television sets for modulation transformers without any problems!  At least for transformers in the 100-watt output range.  Run the center-tapped high voltage secondary to push-pull modulator tubes and use the 120 VAC primary in series with the plate/screen voltage.

Does the impedance always match?  Of course not.  However, no one told the transmitter that the impedances didn't match so the power transformer worked fine as a modulation transformer.  The older power transformers had plenty of current capability and, at least in those that I used in the 1960 time frame, no problems what-so-ever.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: Leslie Smith <vk2bcu at operamail.com>
To: ARC-5 List <arc5 at mailman.qth.net> 
Sent: Friday, April 12, 2013 3:32 PM
Subject: [ARC5] Using a power transformers as a modulation transformer.
 

Dear List-members,
Bry Carling has a pointer (or link) on his web-site, thus:
" How to make modulation transformers out of old power transformers -
by WA1HLR, Tim"

This link does not work.
Power transformers don't work (usually) as a modulation transformer
because the (transmitter final) DC current saturates the transformer
core.
I would be interested to get information about using a power
transformer as a modulation transformer.
I would be interested to hear (or read) about the relationship between
frequency response and quality of "iron" in the transformer.


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