I remember some years back about a rf cable being made for audio work. I
don't remember the particulars but it had to do with high end. I removed
all the pl259 from them and reused them. (I know it being cheep) 73 Gene
K2QWD
----- Original Message -----
From: "D.W. Fearn" <dwfearn@dwfearn.com>
To: <towertalk@contesting.com>
Sent: Friday, September 04, 2009 8:40 PM
Subject: Re: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
>I was using RG-174 as a shielded lead in a product we build and
> experienced exactly the same problem as Larry describes. This was
> from a brand-new, very expensive roll of Belden RG-174. This was to
> the grid of a tube, so even a very high resistance had an effect. We
> have changed to a Teflon-insulated coax and that solved the problem.
>
> Doug K3KW
>
>
>
>
>
>>Date: Fri, 4 Sep 2009 06:55:15 -0400
>>From: "Larry - K7SV" <k7sv@comcast.net>
>>Subject: [TowerTalk] NON-INSULLATION STRIKES AGAIN! RG174 ANOMALLY
>>To: <towertalk@contesting.com>
>>
>>Some of you may remember my posting about our experience with beverages
>>using plastic boxes to house matching transformers. The black plastic
>>boxes
>>turned out to be conductive which obviously led to a lot of head
>>scratching.
>>
>>Well, I've been working a small project using RG-174. I kept finding
>>shorts
>>after putting connectors on the ends. Nothing was making sense so it got
>>to
>>the point that I cut a foot long piece of the stuff, stripped back about
>>an
>>inch of the outer insulated jacket at both ends and pushed the shield away
>>from the ends. I then took resistance measurements between the shield and
>>the ends (didn't strip back the inner insulation, just stuck the meter
>>probe
>>in the end). So I'm still seeing resistance between the shield and the
>>center conductor.
>>
>>On a whim I connected a meter probe to the inner "insulation" at both ends
>>of the piece. Sure enough it was a conductive material. I picked up a
>>couple
>>hundred feet of this stuff from Mendelson's at Dayton a few years ago. As
>>it
>>turns out construction consists of an insulated black outer jacket,
>>stranded
>>copper shield, a black conductive material, a light opaque insulation and
>>then the stranded copper inner conductor.
>>
>>My problem obviously existed anywhere that the inner black "insulated"
>>material was touching the shield.
>>
>>This is the first time I've experienced something like this with RG-174.
>>Actually as I think about it, the stuff must have really great isolation
>>between the center conductor and the braid! I don't think this is typical
>>RG-174!
>>
>>73 de Lar K7SV
>
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