Thanks John. I hadn't thought of isolating the xfmr from the chassis.
I do that with near fields in the studio all the time to get a flatter
response. You may be on to something big here, thanks!
Regards,
Rick/K5IZ
John Lawson wrote:
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
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