[Elecraft] Waterproofing coax connectors (Was: N Fittings)

[Tom Hammond]

Adding to Vic's previous comments... from my own experiences...

At 10:54 AM 2/15/05, Vic Rosenthal wrote:
>I've tried different methods of waterproofing outdoor coax connectors for 
>years, and here is my experience, for what it's worth:
>
>3) Coax Seal -- Does a good job and is easy to use.  I have had 
>connections sealed for years which have stayed dry.  A little hard to 
>clean up when you take the connection apart.

I've found that Coax-Seal works best (for me), if I use it OVER an initial 
wrap of good quality plastic tape (Scotch #33 or #88), and then OVER-WRAP 
it with another wrap of good quality plastic tape. UV will kill coax-seal 
if it's not protected from UV, and coax-seal is simply MISERABLE to remove 
from just about ANY coax connector if you install it directly onto the 
connector (without an inner wrapping).

For the past 5 years, I've switched to self-vulcanizing (silicone) tape... 
see below.

>6) Self-vulcanizing rubber tape -- I've never been able to apply it 
>properly, but looks like it would work well (although I don't know how it 
>would respond to UV).  Tends to want to stick to itself, etc.  Everything 
>is harder when you are on a roof or tower.

The self-vulcanizing tape I use was purchased at Dayton over 3-4 years, 
from an amateur radio club in Minnesota... it is a gray silicone tape and 
VERY flexible and stretchy (almost a 2:1 stretch factor). I apply this tape 
directly to the coax connection, overlapping it about 50%. I then follow 
with a final overwrap of 3M #33 or #88 tape. It has, so far, kept every(!) 
drop of moisture from the connectors it's protected. There was no name on 
the rolls of tape, but I'm told that they were donated to the radio club by 
a 'very large' tape manufacturing company which has three similar letters 
in its name, and this is also located in MN. Hmmm... apparently the tape 
failed one or more of their QC tests, but was still good enough for most 
uses, just not those for which the company was willing to have its name 
shown on the product.

Self-vulcanizing rubber tapes I've seen should work just as well. If they 
appear to want to really stick TO the coax connector (such as Coax-seal 
does), you might want to first apply a protective "don't stick to me" wrap 
of plastic tape (even the cheap stuff will work here), and then apply the 
self-vulcanizing rubber tape, and finally a UV protective layer of good 
quality plastic tape.

Finally, the question of how to 'terminate' a taped wrap... some just pull 
it tight and then yank on the tape until it breaks, wrapping the loose end 
around the already-taped connection.

I've found, from experience, AND from numerous suggestions from those who 
have done a LOT more if that I, that when terminating a wrapped connection, 
it is best to pullout a loose end of maybe 3"-4", CUT it off, and allow it 
to hang free for a short period of time, to allow any previous stretch to 
be recovered by the loose end. Once it has returned to its UNstretched 
length, wrap it snuggly around the taped joint, using the larger diameter 
of the taped joint if possible and WITHOUT much pulling on tape as you wrap 
it. This allows the tape to seal against itself well, but having not been 
stretched, it won't want to unstretch later on when the sun comes out and 
heats up the taped joint, softening the adhesive.

73,

Tom   N0SS