[AMRadio] Seeking advice on testing modulation transformers


John Coleman ARS WA5BXO wa5bxo2006 at pctechref.com
Wed Sep 20 19:49:52 EDT 2006


The RCA 1:1 modulation XFMR I believe is good for only 200 ma in its
secondary.  Don, K4KYV has described a method of removing or reducing the
core gap to make this XFMR capable of very good low frequency response but
it will then require a modulation reactor and coupling capacitor because the
secondary current handling before core saturation will decrease drastically.
The STOCK XFMR will provide fairly good audio down to 200 or 300 CPS
depending on the load and secondary current.  My understanding from Don was
that the primary use of the XFMR was for a tone modulated CW rig or MCW as I
think it was called.  If this is the case then all it had to pass was a
single CW audio tone.  I have used the STOCK XFMR in the past with pretty
good results, and certainly good audio especially in the communication range
but don't expect it to do HIFI from 50cps to 10,000cps and it would be best
to use a reactor with it even if you don't modify the core gap.  

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Mark Foltarz
Sent: Wednesday, September 20, 2006 5:53 PM
To: amradio at mailman.qth.net
Subject: [AMRadio] Seeking advice on testing modulation transformers

  By the way, does anyone have any experience using the RCA 5500  5500
units?

TNX

 de KA4JVY

Mark

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