[R-390] R-392 Mech.Parts Question

[Barry Hauser]

Harry:

As Mike pointed out, that is an Oldham coupler -- excellent photo.

Yes -- you are missing the center part which looks like a thick washer with
a raised line on each side at 90 degrees to each other. Take a look
somewhere in the chassis, and particularly in the case where loose parts
like to roam. It's usually made of metal, but some are nylon, particularly
for the smaller ones.  The part may not actually be a washer shape on this
type, but more of an "X" made of metal or nylon.  The "bars" of the X are
offset as if you nailed two teeeny tiny boards together, or two pieces of
pipe.

If you find the center part, then to install, just loosen one coupling and
back it off so you can slip the center piece in.  The couplings set up with
their slots at 90 degrees to each other, forming an "X".  You can put a bit
of grease or oil on the center piece. Then slide the loosened coupler up
snug, and tighten -- you'll need a bristol wrench -- these aren't allen/hex
screws.

If you can't find the part, try Fair radio, but tell them which coupler it
is -- send them your photo by email.

If they don't have them, you may be able to fabricate the part, or just
wire/tape up the two halves so that it's strong enough to turn as a unit.
There isn't much stress on that coupling as long as you don't try to turn
past the stop.  You could even back 'em off, clean the ends with solvent,
then put a dollop of silicone rubber seal or some other rubbery stuff like
liquid rubber in between and then press together (right on the shafts) and
allow to set.

Finally Harry, the purpose of that coupler was to compensate for mismatched
lineup of the shafts due to variations in manufacture, positioning of the
hole in the front panel relative to the selectivity switch which is way in
the back.  From the look of the photo, yours turned out nearly perfectly
aligned, so you probably could use a solid coupler or make these solid by
means of battlefield improvisation, which would be thematically consistent
with the radio.

As for the DOA, don't fret.  It's common that after storage and a trip that
some of this stuff doesn't work.  Of course, "selective memory" of the
seller is sometimes a factor.  Check the tubes, look for any loose
connectors.  I haven't not been able to make a '392 work yet with hardly any
effort, including the first one I got which has no tubes left at all.
(someone solid stated the whole thing.).

Barry


----- Original Message -----
From: "Harry Joel" <organic@cyberlane.net>
To: <r-390@mailman.qth.net>
Sent: Friday, January 25, 2002 10:12 AM
Subject: [R-390] R-392 Mech.Parts Question


> Hello All
>
> checking out my recently obtained R-392, I discovered
> the Bandwidth (three position) knob was free-wheeling.
> The coupling from knob shaft to rotary switch shaft is
> made up from three pieces. There is a matching slot on
> the top and middle coupling piece.  A part must have been
> there at one time to link the two together. A view is here:
>
> http://www.cyberlane.net/~organic/R-392-Bandwidth-Coupling.jpg
>
> I dont quite understand the need for a three-piece coupling here
> and would like to hear from experts.
>
>
> Any help from R-392 owners is appreciated. I am still in the midst
> of resolving the DOA condition of a receiver that, according to the
> seller was last used some years ago and worked fine. Shoudda
> spend the time to take the Greyhound to the owners city to assess
> the condition of this receiver. Mechanically it seems to be in
> better than average shape. The tag says Serial Number 698 -
> Reworked by Stewart Warner Electronics. Inside markings tell me
> that it was built by Collins.
>
> Harry
>
>
>
>
>
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