[Hammarlund] HQ-180(A) 3035 kHz Xtal Osc (sic) [Filter] Alignment

[Dallas Lankford]

Yes Kim, I meant the 3035 kHz crystal filter.  Thank you for your opinions,
but what I need is someone with actual experience with aligning the 3035 kHz
crystal filter.

Here is what the
180 manual, "Issue No. 4, serial # 1335 and greater" says.

"The bottom adjustment of T1 and the adjustment of T2, together with the
phasing capacitor C79, constitute a 3035 kcs crystal filter circuit and are
factory adjusted by sweep frequency method.  These adjustments should not be
disturbed unless T1 or T2 become defective and are replaced.  The this case,
adjust only the replaced transformer for maximum voltage output.  The bottom
adjustment of T1 is proper for this Frequency (sic)."

Later issues of the 180A manual say otherwise (peak both), but I suspect the
180 manual is correct.  I tried peaking both T2 and the bottom of T1 and got
a very narrow filter response.

Best regards,

Dallas

----- Original Message -----
From: "Kim Herron" <kherron at voyager.net>
To: "Dallas Lankford" <dallas at bayou.com>; <hammarlund at mailman.qth.net>
Sent: Sunday, April 10, 2005 8:36 PM
Subject: Re: [Hammarlund] HQ-180(A) 3035 kHz Xtal Osc Alignment


> Hi Dallas,
> >Has anyone aligned the 180(A) 3035 kHz xtal osc?  I recently bought  a
> >damaged and unaligned '180 (the usual "in good operating condition"
> >according to the seller) in which one of the xtal osc cores had been
> >screwed all the way in.  Presumably the other xtal osc alignment core was
> >tampered with as well.  I believe I can fix it, but would like to
> >correspond with anyone who has "been there and done that."  Thank you,
Dallas.
>
>           That 3035 crystal setup in the front end of the receiver is not
> an oscillator, it's a crystal filter.
> None of the transformers peak that part of the circuit either.  Now, you
do
> have the secondary of the
> 3035 side of the transformer going through the crystal filter, but the
> transformer actually peaks on the frequency
> determined by the 2580 oscillator in the second mixer tube circuit
(working
> from memory here, so the stage may be different).
> I'm fighting with one of those beasts right now.  Mine had T-1 out of it
> and it wouldn't peak on 455 so I had all kinds of stuff
> going on.
>       I can tell you this about this radio.  A VERY GOOD sig gen is a
> necessity to work on it and a dead nut freq counter as well.
> You'll create more trouble than you fix without them.  I'm assuming that
we
> already have a good scope.
>      That 3035 crystal filter does have a freq adjust cap on it to tweak
> the center of the bandpass so that the third IF works properly.
> You can tell if your trouble is in the 1st IF or band pass by taking stock
> of how the receiver performs on the 4 lower bands.
> The 2580 osc and the 3035 band pass filter do not operate on the first
four
> bands.  If your trouble is on all the bands, then it's time to look
> at the second or third IF as the source of your trouble.
>
>
> Thanks!!
>
> Kim Herron  W8ZV
> 1-616-677-3706
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