[Radio Wrangler]

I agree with Stephen, that there must be something wrong with Howard's sig gen. There are reasons why that design isn't wonderful at the best of times, but his example is a lot worse than I'd expect.

Changing the usual suspects hasn't helped, therefore whatever it is, it's something already dismissed as unlikely. It's time for slow and reasoned diagnosis, now the short-cuts have been eliminated. Is the modulation waveform OK? Is the RF oscillator OK when not modulated? Try modulating from a different source (audio amp and modulation transformer) You need to look in overlooked places, hoping to find clues.

David