On Mon, 7 Mar 2016 13:10:22 -0800 (PST), John-Del
wrote:
Interesting. I was always under the impression that *any* lubricant,
whether a fine liquid to a grease would be pushed aside by a
sliding electrical contact and electrical contact would be made
on the molecular level. The lubricant would surround the contact
points and deny air and moisture access to the contact.
Or trap moisture if it was wet when you inserted the connector. Based
on my limited automotive and marine radio experience, I think grease
is a bad idea. However, there are places where it will do as you
suggest. If there's AC or DC current going through the connection,
and the connection is under some pressure, you can get a reasonable
connection. Dry loads such as TV/cable/RF don't work well or for very
long. If the connection moves, and is designed for self cleaning
operation, such as in a switch or relay, it will work for a while.
The problem is not only from the insulating properties of the
dielectric grease, but also from the dirt and grit that are attracted
by the grease. As the dirty grease builds up, it becomes thicker and
thicker. Eventually, the grease hardens sufficiently to force the
contacts to ride up onto the layer of dirty grease, instead of making
a connection. This is a very common problem with potentiometers that
are lubricated with greases diluted by solvents. When the solvents
evaporate, the remaining grease is almost thick enough to cause the
wiper to ride up onto the grease. Few people do this, but as I
mentioned, the grease gets thick enough from being mixed with carbon
particles scraped off from the resistance element to cause a problem.
If you need to be convinced more, please buy some phosphorescent
powder on eBay.
http://www.ebay.com/sch/i.html?_nkw=phosphorescent+powder
http://www.allureglow.com.au/powder.php
http://www.crimescene.com/store/index.php?main_page=product_info&products_id=76
Try to get the finest grain powder possible. Most of my pile is 10
and 15um. I haven't tried the criminal investigation stuff, but I'm
fairly sure it will work.
Also get a UV (365nm) flashlight. Mix a little with your grease of
choice and apply to a flat piece of steel, aluminum, or copper (so you
can see what you're doing). Rub it in and then wipe the grease off
without solvents. Use the UV light to see how much is left. There
should be plenty. Now, try some common solvents. More will
disappear, but you'll still have plenty of grease left on the surface.
If you have a microscope handy, you can see a microscopic thin layer
of glowing grease.
I've used dielectric grease on vintage automobile harnesses and bulb
sockets and have never had a problem with contacts afterwards.
I bought an Isuzu Trooper cheap from someone that took it to Burning
Man. When it came back, many of the electrical connections were
intermittent. The cause was dielectric grease in the connectors,
mixed with fine desert sand and dust. After some experimentation, I
used a small ultrasonic clean and trichlorethylene to dissolve the
grease. I initially made the intermittents worse, but after two more
applications, the contacts were finally deemed clean.
Diversion: Of all the connectors available, the common F-connector is
the only one that is made from enough dissimilar metals to insure
galvanic corruption. The connector shell is made from aluminum or
brass. It is plated with alodine 1200, nickel, chrome, gold, pyrite,
or nothing. The coax center wire is copper plated steel or solid
copper. The foil and braid shields are aluminum. With this mix of
dissimilar metals, if you get any water inside, something is going to
corrode.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558