[Hallicrafters] SX-28 RF alignment

[Al Parker]

Hi Julian,
    I suspect removing and replacing the section will not find or fix the
problem.  I'd suspect a mis-wired connection when you put things back
together, maybe in just the oscillator section.  It's been a long time since
I messed with an SX-28, but I've done several (enough to have sworn off of
them), but IIRC there were a cupla "strange" things you had to do, like
sever one solid wire connection and resolder it going back together.  I made
sketches of things before they came apart so I'd have less trouble ging
back, but still had a somewhat similar problem to yours on one of them.
    I know you've got some good test eqpt, you could see just what freq. the
oscillation is, and how it changes with the main tuning, then take a look at
the osc. schem, and maybe figure it out.  Or take a close look at the schem
& your connections.  Or maybe it's something else that's oscillating.
73,
Al, W8UT,
New Bern, NC
www.boatanchors.org
www.hammarlund.info

----- Original Message -----
From: "Julian Bunn" <Julian.Bunn at caltech.edu>
To: "Mike Everette" <radiocompass at yahoo.com>
Cc: "Hallicrafters List" <hallicrafters at mailman.qth.net>
Sent: Sunday, March 18, 2007 9:52 PM
Subject: Re: [Hallicrafters] SX-28 RF alignment


> Hi Mike,
>
> Yes, the radio worked beforehand. I really need to double check
> all the connections, but I am reluctant to remove the RF box again
> (as you may imagine!)
>
> Julian
>
> Mike Everette wrote:
> > Did the radio work before you went into the RF box?
> >
> > It sounds like you may have left a ground off,
> > somewhere.  I wouldn't think the problem is in the
> > oscillator if the RF oscillation is present on the
> > antenna post.
> >
> > 73
> >
> > Mike
> > WA4DLF
> >
> >
> >