[R-390] Lubricate my 390A/URR

Sat, 14 Feb 2004 19:40:27 -0500

Hi Max:

I don't know where you would find those MIL lubricants, but they are
probably no longer the best choice anyway.

R-390A owners use a number of different favorites.  One is synthetic motor
oil, such as "Mobil One" here in the US -- 10W-30 or similar.  Some use
synthetic gear oil which is 70-90 weight.  One quart or liter is enough for
at least a thousand radios.  Avoid hypoidal gear lubricant which contains
sulfur.  Some say the fumes cause oxidation of silver plated contacts, but I
just do not like the aroma.

The main reason for favoring the synthetics is that they should never harden
up or become sticky. However, someone pointed out that quality regular oils
and grease should be good for many years and it would be OK to have to clean
and re-lubricate every 5 to 10 years or so.  (In other words, synthetic lube
might be over-doing things -- but we are R-390 owners with 75 lb. radios, so
perhaps over-doing is something we like to do ;-)  (Like making sure that
who ever owns the radio 50 years from now is happy with our work.)

You are likely to already have some oil that will do the job.  The main
thing is to clean the gear train completely and use very little.  A single
drop on the end of a wire or paper clip is enough for a bearing or bushing.
Just coat the gear teeth with a small amount using a brush.  Make certain
that the rollers on the slug racks (cam followers) spin freely.  (Keep oil
away from the antenna trimmer shaft.)

I sometimes apply a molydenum paste lubricant to sliding surfaces, such as
the inside surfaces of the RF deck frame, ends of the slug racks, etc.  You
apply the paste as if you were polishing a car -- rub it in and buff.  It
fills the pores in the metal and leaves a slick, dry surface.

Do you have the R2 version of the Y2K manual?  I may be wrong, but I thought
some notes were added about lubrication.  If not, you can find more in the
"Pearls of Wisdom" on Al Tirevold's site.

Barry

----- Original Message -----
From: "massimiliano" <[email protected]>
To: <[email protected]>
Sent: Saturday, February 14, 2004 3:50 PM
Subject: [R-390] Lubricate my 390A/URR

In the Y2K-R2 manual I read I have to use MIL-L-7970  and  MIL-G-7421 for
lubricate my 390A/URR. Were can I buy this type of oils ?

73  de IK0JJZ   Max

Sorry for my English.

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