[RFI] RFI Digest, Vol 58, Issue 27

[Tom Cox]

Don't know about RF characteristics, but some of those products have a 
strong acetic acid smell as they cure. They might be corrosive to 
copper. You can buy silicone caulk that is (supposedly) low in acetic 
acid. I don't know if foam is available similarly. You might try a test 
batch in a PVC capsule with some copper wire, and see how it looks after 
a week or so. If it eats the wire, RF characteristics are moot.

As to RF characteristics -- If you find foam that doesn't corrode the 
copper, and you can afford a realistic test, build a trap in PVC, run it 
on an analyzer (MFJ259B or similar), and run it again after filling  it 
with foam and allowing it to cure. Wasting one set of trap components is 
better than wasting a bunch. If you share your results with the list, 
many will probably appreciate it. Good luck.

73,
Tom, KT9OM

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> Today's Topics:
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>    1. Foam (Rick D)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 29 Oct 2007 18:21:28 -0700
> From: Rick D <n6pe at pacbell.net>
> Subject: [RFI] Foam
> To: Topband <topband at contesting.com>, SCCC <sccc at contesting.com>,	RTTY
> 	<rtty at contesting.com>, RFI <RFI at CONTESTING.COM>
> Message-ID: <47268718.5020401 at pacbell.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Anyone know the electrical/RF characteristics of the various expanding 
> foam products?
>
> I am building some traps for my 160/80/40 L and was considering filling 
> them with foam. Traps are made from old RO water filters with #12 wire 
> and HV ceramic caps mounted inside.
>
> Thanks,
>
>