[AMRadio] Dow Corning DC 4

[Jim Wilhite]

A couple of weeks back I asked if anyone knew what the grease 
composition was in the little packets furnished with commercial VHF 
antennas.  Several people responded with the answer Dow Corning DC 4.

I had a friend who send me a couple of packets and I put it in several 
connectors that I am using now in my temporary transmission line.  First 
I measured the reflected power into a dummy load from 1.8 up to 29 Mc. 
I did that in the middle of the 6 bands.

Then I put the grease in one connector and measured at the same points. 
The reflected power did not change so I put it in the rest of the 
connectors.  Still the reflected power did not change and the power 
measured at the dummy load did not change.

Given those results I clinched my jaw and ordered a tube of it, about 5 
oz.  I forget the exact cost but it was about $20.  I made the decision 
to put the grease in my PL 259 connectors because over the years I have 
used them in all sorts of installations.  I put tape around them, I put 
heat shrink over them after taping them but in most cases I found 
corrosion on the center pin from condensation.

So by filling the connector this should help keep that problem down to a 
very little bit.  I hope this time I never have to move and this will 
last from now on.  Thanks to all of you who posted your thoughts and 
suggestions.  In my measurements it is a worth while thing to do 
particularly if you live in high humidity areas.

The only thing to watch is it has silicone in it.  If you use it on 
something to be painted, you will regret it.  Paint will not stick to 
surfaces that have had silicone on them.  And it does not matter how 
much you clean the surface, it will always cause trouble.

Jim/W5JO