[AMRadio] Ultrasonic feedback

Larry Szendrei ne1s at neandertech.com
Tue Feb 3 08:55:16 EST 2009

> In my experience the most common cause of these symptoms isn't feedback
> within the modulator itself, but RF rectification somewhere in the audio
> chain prior to the gain pot.

I also wanted to add: you can determine if this is the problem by testing
the transmitter into a proper dummy load (i.e., not a light bulb, which
will radiate to some degree). If the squeal goes away, or if you need to
advance the audio gain considerably further for it to appear, it's
probably RF rectification that's your problem.


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