Date: Fri, 15 Aug 2014 22:10:25 -0400
From: Charlie Gallo <Charlie@TheGallos.com>
To: Chuck Smallhouse <w7cs@theriver.com>
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Black UHMW ?
On 8/15/2014 Chuck Smallhouse wrote:
...snip...
> My question is the black version at all conductive ? I'm considering
> using scrap pieces of it, cut into plates, to mount yagi elements to
> their boom ? Someone mentioned that the white variety can
> deteriorate, when exposed to UV ?
...snip...
Looking at the data sheets, they do not specify the Dielectric
constant of black uhmw plastic, probably because black uhmw plastic is
reprocessed, so the can't. It is listed has having the same
Dielectric strength as the "natural" 900 KV/mm (BTW, the glass filled
is also the same)
That said, be careful, as there IS anti-static uhmw plastic, which is
intentionally at least semi-conductive, and is black, so my answer
would be "It depends on which uhmw" you get
You could with Acetal (aka delrin) which will only have a dielectric
strength of 420KV/mm
That said, for the combination of strength, dielectric strength etc
(but is NOT a good bearing) if is HARD to beat G10-G11 phenolic (The
fireproof grade FR-4 is what good circuit boards are made from).
Pretty much all the grades of phenolic are available from McMaster,
but that said, it is a bear to machine (plan un using carbide, and
having dull bits
--
73 de KG2V - Charles Gallo
Quality Custom Machine-shop work for the radio amateur (sm)
## I thought phenolic absorbed moisture ?? At least the old style phenolic
did. Fiberglass based material might work.
I have found that most grades of white uhmw will succumb to UV after time,
turm brittle and start to crack, and break off.
The black uhmw might be the ticket for a bearing plate..... and if it doesn’t
conduct.... used for ele to boom mounts.
The grey pvc tubing found in home depot electrical dept works great to
insulate eles from the al boom to ele plate.
Then a solid fiberglass insulator in the middle...for DE.
Jim VE7RF
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