[R-390] Broadcast Band On Other Bands

[David Wise]

> From: blw [mailto:ba.williams@charter.net]
> 
> Yes, mine is a 56 Motorola and you described the effect 
> better. It is a
> sudden gain without noise or harmonics. I have not had the IF 
> 
> Barry
> 
> > Mine does the same thing.  It's almost like it gets a 
> sudden 10dB gain.  Is
> > yours a '56 Motorola?  I wonder if it's 
> manufacturer/contract specific.
> > 
> > Barry(III) - N4BUQ

I think we're onto a trend.  My '54 Motorola does it too, on 4-7.
In CAL, the carrier meter reads 10-20dB lower than on the
other bands.  I can clear it by briefly! shorting the middle
RF coil's trimmer to ground.  Days go by, then it's back down.
I'm not saying it's the trimmer (the short is just a convenient
way of generating a lot of EM racket), but that's where I'll look
first.  IIRC it doesn't get detuned, just loses gain.  I suspect
loss of Q due to a high-resistance contact.  Now that I have
a nice signal generator, I'll take some stage gain readings
while it's bad, then clear it and repeat.

By the way.  My nice signal generator does need one bit of
help.  Anybody got a cover plate for an HP 8640B modulator
housing?  Mine came without, and I bet it would radiate
less if it were there.  Doesn't have to be B; I'm sure an A
would work fine.  (Was there a non-A?)  I can't fabricate
one, since I don't have a milling machine to hollow it out.

73,
Dave Wise