Topband: Using GE silicone as antenna sealant.

Shoppa, Tim tshoppa at
Mon Mar 18 09:25:54 EDT 2013

After several less than satisfactory experiences with various outdoor sealed boxes and junctions etc. I have had my ladder line, transmit antenna, and all junctions completely exposed to the weather for the past 4 years with no problems.

The problem was never as bad as the corrosion due to sealant, but I found out that what was happening was that I was sealing water in! Obviously I was doing something "wrong" but many of these containers had no lead-ins or holes in the top, only sealed lead-ins with drip loops at the bottom.

I briefly had a NEMA rated junction box with watertight cover and seal over the spark gap, but after water started accumulating in there, I simply removed the cover. Every fall I go blow the leaves and bugs out.

On the receive antenna side... My K9AY relay board and termination resistor are covered by a Tupperware dish but are exposed at the bottom. I had made a brief attempt at sealing them inside the Tupperware but despite drip loops and all the wires entering only at the bottom... I found water accumulating in the Tupperware even though I swear it hadn't rained since I had installed it. I don't have any fancy conformal coating or anything on the K9AY relay/transformer/termination board.

Tim N3QE

-----Original Message-----
From: Topband [mailto:topband-bounces at] On Behalf Of Don Kirk
Sent: Monday, March 18, 2013 8:17 AM
To: wa3mej at
Cc: topband at
Subject: Re: Topband: Using GE silicone as antenna sealant.

WA3MEJ said :

be very sure that if you pick GE silicone sealant.. (RTV or whatever you
> call it) DO NOT use the kind that has acetic acid in it.

This is a very good point, and this is the reason I use GE Silicone Sealant II versus GE Silicone Sealant I.  GE Silicone Sealant II is a "neutral cure silicone" whereas GE Silicone Sealant is an acid or acetoxy cure silicone.
  "Neutral Cure" silicone means no acids are released during the curing process (note this information was obtained from the GE website).

Don (wd8dsb)
Topband Reflector

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