[TowerTalk] insulating properties of cured and uncured silicone caulking

[john at kk9a.com]

Why do you think the antenna impedance is wrong?  Are you checking it at the
feedpoint or through 1/2wl multiple length of coax?

Over the years I have used all kinds of silicone caulk (even acetic) on
antenna connections without noticing any issues however I do not recall ever
using it across a SO-239. I highly doubt this is causing an issue but if it
was a concern and reachable, you could insulate the center conductor with
shrink tube or tape prior to re-caulking.

GL,
John KK9A

  

N3AC wrote:

I've covered the back of a SO-239 at an antenna feedpoint with silicone
caulking. It wasn't electronic grade... it was probably from Lowe's or HD.
GE "SIL2KB CLR", Mod. GE284. It's Silicone 2 (without acetic acid).

I started checking my antenna impedance immediately, and all my readings
were lower than expected. Then I started wondering if uncured product was
more conductive than cured.

Then I found that silicone caulking can be anywhere from "high dielectric
properties" to pretty conductive, depending on what the mfgr stuffs in with
it.

In hindsight, I should have checked the antenna before gooping it. And I
should have sprung for some electronic grade, maybe.

Ok, here are the questions - but feel free to to add more if I've missed
the basic issues
:
1. Does anyone have experience with GE284 for electrical insulating
properties, specifically RF, and what was it?

2. Would you expect properties to differ between cured and uncured GE284?
If so, would you expect uncured to be more or less conductive?

thanks in advance,

Dave Haring N3AC
Forest, Virginia