[Boatanchors] Antenna sealing questions, silastic?

[Robert Bethman]

Phil,

Need to watch which RTV/Silastic you get and use.

Many of them give off acetic acid during the curing.  Bad for any joints.

GE has its 737 silicone sealer.  It is completely inert.  Doesn't give off anything that will cause issues.  It is not inexpensive though.

Regards, Bob Bethman

-----Original Message-----
From: Boatanchors [mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Phil
Sent: Wednesday, March 09, 2016 6:18 PM
To: Boatanchors <boatanchors at mailman.qth.net>
Subject: [Boatanchors] Antenna sealing questions, silastic?

Hi All,
Been doing antennas many, many years, but I still have a question, maybe
2 :)  Yeah, this isn't boatanchors, but there are a lot of antenna experts out here.

I just recently installed a TYT TH-9800 (Quad Band clone of the Yaesu
FT-8900) in both the shack and the Ford "Screw".  Both radios are installed and get excellent audio & signal reports.  I don't expect to use the 10M & 6M (FM) bands, just got them to use for 2M/440. They were only $6 more than the TYT 7800 dual band radios (clone of the Yaesu 8800).

While I ordered the radios I also ordered a new dual band base antenna, the Tram 1481 (17 foot colinear).  Supposed to be a pretty good antenna, but if I'd read the reviews first I might have chosen a different model as some users have had problems with water ingress (sp?), even though they said they sealed it well. Others say they've never had a problem with it.

Anyway, I didn't think to order coax seal, and RadiosShack is totally gone from the Central Valley here in Calif.

The antenna has 3 fiberglass sections that screw together and is supposed to have factory seals, which apparently don't do the job.  Many folks seal the sections with Coax seal or other methods, and "Silastic' 
repeatedly came up.  WHAT pray tell is "Silastic".  It sounds like something a woman might wear.  I sort of thought about heavily wrapping the joints with black plastic tape and them put a coat of clear RTV over that.  Those are things I can obtain locally.

OR is there something else available at the usual hardware store (ACE, Lowes etc) that might be better, especially to seal the coax fitting at the base. . .

By the way, the feedline I bought for this antenna is a 25 foot length of LMR-400 with factory PL-259's, bought from MPD Digital it looks like a VERY good product!  It's my first experience with LM-400, I didn't realize it was as stiff as it is. IF I do the install RIGHT it should be good for a long time (I'm getting too old to have to re-do antennas and push-up poles very often).

We DON'T get a lot of rain here (other than this El Nino year) and seem to be in a perpetual drought, but once I put the antenna up I don't want to have to take it back down to letthe droplets of water that might collect in the bottom dry out.

Are there better ideas here?