[Hallicrafters] SX-28 RF alignment

[Duane Fischer, W8DBF]

Julian,

You might try paying a visit to W8UT, Al Parker's web site. He is one of the 
brightest tech's out there in vintage radio land and has numerous articles, 
some "How To", on his personal web site.

I do not know the address Julian, but if Al reads this perhaps he will drop 
you an e-mail with it.

Good luck OM! And TNX to W8UT for his invaluable contributions over the 
years.

Duane Fischer, W8DBF/WPE8CXO
dfischer at usol.com
HHI: Halligan's Hallicrafters International
http://www.w9wze.net
HHRP: Historic Halligan Radio Project
hhrp.w9wze.net

----- Original Message ----- 
From: "Julian Bunn" <Julian.Bunn at caltech.edu>
To: "Hallicrafters List" <hallicrafters at mailman.qth.net>
Sent: Friday, March 16, 2007 8:01 PM
Subject: [Hallicrafters] SX-28 RF alignment


>I recapped the RF box on my SX-28, and also replaced resistors out
> of spec.. Since putting the RF box back together, I performed an
> IF alignment, which went very well.
>
> Now I have come to align the RF, and there is clearly something wrong,
> but I have insufficient experience to tell what the problem is, and am
> hoping for some advice from seasoned experts :-)
>
> Basically, looking on the 'scope, there is RF oscillation at various
> points throughout the box. The frequency of the RF varies as I
> rotate the main tuning and bandspread caps. The RF oscillation
> is on the A1 terminal, for example. The frequency of this oscillation
> is about 6MHz at the bottom of the broadcast band.
>
> Is the diagnosis that I have a short somewhere in the local oscillator?
>
> How would you go about pinpointing the problem?
>
> Thanks!
> Julian
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