K7ITM wrote:

A solution to that is to... feed the RF stage its DC through an audio
choke, and capacitor-couple the audio into the RF deck...

this is of course a perfectly good solution, at least from a technical
point of view, but... audio chokes are nowadays precious rare modern art
masterpieces and the only practical way to get a suitable one is to
wind it yourself, which is more or less the same as winding your own
transformer

...I've also seen a design where the modulator was single-ended but used
a push-pull transformer; the RF amp was fed its DC through the other
side of the center tapped winding. That allowed reasonable balance of
the DC in the transformer, and worked decently. ...

been there, done that - it sure works, in a fashion... but not very
satisfactorily. At the time when I tried it, I reasoned that using a
single ended audio tube with a plate current more or less similar to
that of the RF amp tube, the total core flux in the transformer should
be more or less balanced - what I did not know then (I was *very*
young...) was that average plate currents mean very little, saturation
occurs because of peaks!

--
73 es 51 de i3hev, op. mario

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