[Hammarlund] Fw: Hq170 hum

[Craig Roberts]

Hello Lee,

I agree with you -- absolutely. The increased audio bandwidth afforded by my
new output transformer is quitre possibly at the root of the hum problem. I,
however, have no idea of what the factory "normal" passband was, since the
radio -- as I got it -- had been retrofitted with a low-end universal type
transformer. The output stage wiring had also been modified and the audio
was plagued by a limited bandwidth and a lot of noise. I had to do something
to remedy this.

I didn't arbitrarily install a "high-fidelity" transformer in dumb 'n doomed
attempt to transform a '60's communications receiver into an audiophile
set -- it's simply what I had available. I must admit, though, that while
the new transformer seems to pass audible hum, it's also cleaned up the
sound considerably.  If possible, I'd like to attenuate the hum without
unduly compromising the new intelligibility.

Barring that, I'd like to find an original output transformer for the
HQ-170A (the late xfmr with the dual 3.2 and 500 ohnm secondaries), but
these are understandably scarce. I'd also like to find out how the factory
leads were routed so I could replicate the original wiring. At least then
I'd know what the radio USED to sound like. I'd be happy jus tto know that.

Anyway, thanks again for the wisdom, Lee. And thanks to everyone else who's
responded. I'll keep you posted.

73,
Craig
W3CRR