{Collins} Re: Fwd: Re: KWM-2A problems and tubelore question



Bob,

There's a Dennis Brothers fix for those loose slugs [Z5]. Dennis recommended
a piece of waxed cable harness lacing twine, flattened and thinned out, and
then rapped it around the core. One, but no more that two layers should do.

Stu, k2qde

----- Original Message ----- 
From: "Robert Stewart" <bob@xxxxxxxxxx>
To: <collins@xxxxxxxxxxxxx>
Sent: Sunday, October 24, 2004 6:22 PM
Subject: {Collins} Fwd: Re: KWM-2A problems and tubelore question


> Forwarded to list as requested.
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> Subject: Re: {Collins} KWM-2A problems and tubelore question
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> Bob,
>
> Welcome back.  You will enjoy the KWM-2A.  Here's what I did with mine
when
> I bought it a few years ago:
>
> Clean the switches, relays (including the one in the final compartment -
> remove the shield from the bottom nuts), connectors, crystal pins, and
tube
> pins with DeOxit D5 cleaner (Antique Radio Supply).  Apply to metal only
on
> the fiber switches, if you can.  Try not to let it soak into the fiber.
> Then exercise all the switches, etc.  Sometimes the bottom shields around
> the bandswitch sections can become less than perfectly grounded, and that
> can cause weird oscillation problems, esp on 3.5 MHz.  Cleaning and
> reseating the aluminum shield sections is the recommended solution to this
> common problem.
>
> As for tubes - I substituted as needed.  At least you can swap between
rigs.
> I have a box of tubes and sometimes substitute several.  Tube checkers are
> good, but nothing beats a known good sub.  Once you have one of the rigs
> running well, you can always refer to it.  Use original 6146's, not A's or
> esp B's.  W's sometimes work well.  Blue glows don't sound good, but use a
> sub to be sure.  Antique Radio has the tubes at a reasonable price.
>
> Perform an alignment per the book.  Do not skip anything, and follow the
> directions.  Yes, if you know exactly what you are doing, you can tweak
the
> caps with the finals enabled - but it's easier to just follow the
directions
> unless you are very comfortable with the risks to the final tubes.  I
> learned that it's best to do exactly what they recommend and don't cheat.
> In the long run, you will save time by being thorough.
>
> Hope this helps.  You should be able to achieve full output, all bands, no
> funny oscillations.  As for Z5, it is a birdie nuller.   You should be
able
> to hear a bird at 7.045 and be able to null it out (see p. 5-12 of the
> militiary manual).  It should not affect the frequency of the received
> signals, esp on other frequencies.  If it does, you have some other
problems
> not associated with Z5.
>
> 73,
>
> Rocco N6KN
> ----- Original Message ----- 
> From: "Robert Stewart" <bob@xxxxxxxxxx>
> To: <collins@xxxxxxxxxxxxx>
> Sent: Sunday, October 24, 2004 7:06 PM
> Subject: {Collins} KWM-2A problems and tubelore question
>
>
> > Hello to the group.  I have returned to Ham Radio
> > after an almost 16 year absence and decided to get the
> > radios I wanted the first time: Collins.  Of course, I
> > bought them from ebay with the predictable result: one
> > works pretty good and the other has problems.
> >
> > My background, I used to have an Advanced class
> > license, and I taught electronics in the Air Force, so
> > I have a fair amount of technical skills.  Plus, I
> > built several Heathkit rigs and did some homebrewing
> > back in the day.  I've returned to Ham Radio with an
> > Extra this time.
> >
> > My questions;
> >
> > My KWM-2A has a self oscillation somewhere.  When I
> > tune Z5, its frequency changes.  Any ideas where to
> > start?
> >
> > Next: in section 4.5.1.2 of the instruction book, it
> > says to disable the screen circuit before proceeding
> > with the 455-KC IF alignment.  Is this really
> > necessary, or is it sufficient to simply bias the
> > finals past cutoff?  I'm guessing that the real
> > purpose behind removing the screen voltage is to just
> > prevent overheating the finals while messing with T1
> > and C54.  What's SOP here?
> >
> > Finally, I've forgotten most of my "tubelore".  I also
> > have a KWM-2 which works pretty good.  But, both rigs
> > have one tube (different on each) that glows blue.  In
> > one, it's V13.  In the other, it's V3.  Swapping both
> > out doesn't fix the problem.  Is this a sign of some
> > voltage or drive problem that I need to address.
> >
> > Thanks in advance,
> >
> > Bob, AE6RV
> > Sponsored by the Collins Collectors Association
> http://www.collinsradio.org
> > Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
> > Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
> > 1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
> > Sun AM Net: 29.050 Mc-1200 Central
> >
> >
>
>
>
>
> Sponsored by the Collins Collectors Association
http://www.collinsradio.org
> Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
> Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
> 1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
> Sun AM Net: 29.050 Mc-1200 Central
>

Sponsored by the Collins Collectors Association http://www.collinsradio.org
Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
Sun AM Net: 29.050 Mc-1200 Central






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