[TowerTalk] Black UHMW ?

[Jim Thomson]

Date: Fri, 15 Aug 2014 22:10:25 -0400
From: Charlie Gallo <Charlie at TheGallos.com>
To: Chuck Smallhouse <w7cs at theriver.com>
Cc: towertalk at 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