[AMRadio] push pull output XFMRs and neg feedback


John Coleman jc at pctechref.com
Thu May 14 19:00:35 EDT 2009


That is a possibility Dennis however there is little if any difference in the open loop gain of the two circuits or their output level before clipping about (40 watts). I was thinking that perhaps the primary wires were color coded incorrectly, as I am nearly positive they are, and the secondary may be as well.  As a result I may have the speakers tied to the 16ohm output and taking the feedback from there would be greatly different than the 8ohm connection.  The XFMR load would be entirely different and untold other differences.  I will check ringing and resonance as well though.

Thanks for the input Dennis
John Coleman, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Dennis Gilliam
Sent: Thursday, May 14, 2009 5:48 PM
To: Discussion of AM Radio in the Amateur Service
Subject: Re: [AMRadio] push pull output XFMRs and neg feedback

It sounds like you may have a shorted turn in one of them, NOS
notwithstanding.  It has happened to me, and it forms a tuned circuit
resulting in a phase shift as it is an LC network now.

73 de W7TFO


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