How do I apply anti-oxidant grease to the junction of two metals? Do I put
a dab of grease on each mating surface then clamp the metals together, or,
clamp the metals together and smear grease on the outside?

I have a Yaesu FT-857D and an ATAS-120 installed in my truck -- I have had a
problem with the ATAS-120 -- my FT-857D would not recognize the antenna.
After checking every possible problem, I made a discovery.

Using my ohmmeter, I found there was continuity between the antenna mount
and the body and frame of the truck, but, there was no continuity between
the antenna connector and the antenna mount. The connecter is a VHF Type M
mount; the threaded portion of the connector passes through a hole in the
antenna mount and is tightened to the mount with a big nut. There was no
connection between the connector and the antenna mount, thus, there was no
connection between the outer shell of the antenna connector and the truck
frame and body.

I removed the big nut that holds the antenna connector and used emery paper
to sand the surface of the nut that contacts the mount, and, I sanded the
part of the mount that contacts the nut. When I re-installed the antenna
connector, the antenna works perfectly. The problem was a bad ground
between the antenna connector and the antenna mount because of oxidation on
the two mating surfaces.

I have found a source of anti-oxidant grease that's used on electrical
connections and I will put this stuff on the connector-mount junction to
prevent further oxidation. Here's the question: Do I loosen the nut and
put grease between the nut and the antenna mount -- similar to putting
thermal grease between a heat sink and the surface of a transistor -- or, do
I tighten the nut and smear grease on the outside, not on the mating
surfaces? I suspect I should put the grease on the mating surfaces between
the nut and the mount -- loosen the nut, smear on grease, tighten the nut.

Thanks.