Re: the discussion of acoustic/mechanical modulator feedback - my Valiant 'talks' - and loudly - when I'm hitting it good. I have a broadcast mike, preamp, EQ and compressor in my audio chain - all fed into the (as yet unmodified) Valiant input. (BTW, my buddy's Johnson 500 'talks' loud enough to heard in the next room - he also has to watch his mike placement.)
Of course, when On The Air - the Valiant rings and howls - I have to move the mike, change the locations of various things - and quite likely put the Valiant on an acoustic absorbing pad of some kind. Lead-filled 1/2" neoprene comes to mind - I've used that building theatres and recording studios - it's amazing what it sucks up.
Another thought re: 'potted' vs. 'open frame' Mod Iron occurs to me (still with acoustic-designer hat on)... isolating the offending transformer from the chassis might mitigate some of these feedback effects - maybe as easy as removing the mounting bolts and resting the device on hi-temp dense foam or even thick felt padding - something to break the close mechanical coupling between the transformer core and the chassis of tghe rig. Maybe easier than re-doing the modulator, or even exiling tghe poor thing...
I've done exactly this with building distro transformers of up to 100KVA - and in fact there are several commercially-available solutions for just this kind of thing... hit the Big Breaker and half that end of the building goes hummmmmmmmmmmm....... ;}
Cheers John KB6SCO
