[TowerTalk] RG-174.Conductive plastic. K0Ff

David Robbins k1ttt@berkshire.net
Sun, 11 Jun 2000 18:37:16 +0100


belden catalog does state that "rg-174/u type" has a conductive layer under the
braid, but only claims 88% shield coverage.  this is compared to the foil
shields under the braid that they claim 100% coverage on.  they also group
"rg-174/u type" under 'low noise' cables and do not give loss figures for it. 
this is in contrast to the "rg-174/u mil-c-17d" that they do not show with a
conductive layer and do list loss figures on that are pretty darn bad.  you
might want to check the losses on that stuff before you use too much of it.

K0FF wrote:
> 
> The other day, I remoted the meter on a Bird Wattmeter, and it would not
> work with  jumpers I made from RG174. Today another jumper using the same
> stuff for a keying line went goofy, so I decided to solve the mystery once
> and for all. After all I have a 3000 foot spool of this stuff from a
> hamfest...
> Wound up being a partial short from center conductor to shield. This
> particular cable has  a black plastic sheath under the braid, and over the
> inner insulator. I never knew that this sheath is conductive to electricity!
> Not much but since I left it on there, and actually stuck it into the center
> pin of the connector, it presented a high impedance short/
> 
> Mystery solved. All connectors cut off, and will be redone properly...
> 
> Had no idea. Must be for some special shielding application.

-- 
David Robbins K1TTT (ex KY1H)
k1ttt@berkshire.net   or   robbins@berkshire.net
http://www.berkshire.net/~robbins/k1ttt.html

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