[Heath] AR-3 Tuning Cap

[Robert Carroll]

Hi, Ken-

I seem to have trashed all the messages I had stored away on this, but I
remember most of the procedure.  It worked off the bat on two of the units
but the third one had an additional wrinkle.  If you look closely there are
concentric shafts coming out the front of the tuning cap.  The race "ball
bearing" Vernier affect takes place in the front bearings.  The problem is
that the little shaft turns at the same degree rate as the large shaft if
the little one can't rotate independently of the larger shaft because the
two have become unintentionally become "glued" together by solidified
sludge---which could result from tobacco smoke or a list of other things.
The solution to start with has been outlined here.  You squirt something
which will evaporate--such as naptha--down the very small gap between the
two shafts and hold the large shaft fixed while rotating the smaller one.  I
would guess it would be best to orient the cap so that whatever loosens up
can drain out, but that's tough to do while the cap is still mounted in the
unit.  And it's not a walk in the park to take the cap out of the unit.
People who have had success with this say to do this over a period of days
as you most likely will not get all the gook out on the first day.  I had to
go to a Walgreens to get lighter fluid, and it was locked in a shelf near
the checkout.  The clerk had no idea they carried lighter fluid and didn't
know what it was.
This procedure cured two of my three generators.  I had gotten the third at
a great price on ebay from what turned out to be one of the pieces of one of
the new Heathkit companies.  I called the guy at that desk, and he was very
helpful.  I told him about the cap and he suggested the lighter fluid
treatment.  I was hoping he had a junker he would take a working cap out of,
but he didn't.  He told me to call him back and if I had not been able to
free the Vernier he would help more---including taking the unit back.  So I
repeated the procedure over four days with no luck---but a little
improvement.  Turning the inner shaft would turn the outer one smoothly
until a t the same angle time after time there was no further movement.  If
I manually nudged the plates a few degrees the small shaft would move the
plates for another significant angle and it would stop again.  I reported
back and he suggested the soldering iron treatment---and he recommended
taking the cap out to do this.  I did see more shellac type substance come
out
when I did this but the slipping continued.  I called him back and he said
to send him the cap, which I did.  A few days later he called me back and
said the cap was on the way back working fine--which it did.  I may have
this a little muddled but basically the inner shaft is actually a composite
shaft--part metal and part some sort of non-metallic composite.  One fits
into the other and secured by two dimples--perhaps punched.  He told me he
had seen this before and he had to punch them again.  It's been working fine
now for several years.  I have to say I was very pleased with how helpful he
was.  Apparently his little piece of the revived Heathkit company is to buy
used units and resell them.  Unfortunately I seem to have lost his contact
info.

Bob W2WG

-----Original Message-----
From: Kenneth G. Gordon [mailto:kgordon2006 at frontier.com] 
Sent: Tuesday, April 19, 2016 7:31 PM
To: Robert Carroll <w2wg at comcast.net>
Cc: Heathkit List <heath at puck.nether.net>
Subject: Re: [Heath] AR-3 Tuning Cap

On 19 Apr 2016 at 15:56, Robert Carroll wrote:

> That´s the same way the LG-1 and IG-42 signal generators work, and 
> getting solidified lubricant out is nasty but usually successful.

Bob: Please detail how you get that garbage out of there and get the
capacitors back in operation. I also own an IG-42 which I want to put on the
bench.

> The generators are not very usable without the fine-tuning capability.   

Neither are the AR-3s... :-(

As I mentioned here, I think that if I remove the caps from the receivers,
turn the plates so that the rotor plates are at 90 degrees to the main body
of the cap, then immerse them up past the shaft in something like PB
Blaster, or WD-40, that eventually, they would free up and begin to work.

What do you think of this idea? How have you "resurrected" yours?

The gap between the two pieces of shaft is very small...

Ken W7EKB