oddly enough, I found some 'Direct TV High Definition' RG-6 that has a solid
coppercenter conductor. it seems to behave better at low frequ's than the
copper cladsteel. less loss and closer to 75 ohms Zo. ( i get 79 ohms on 160m
with my VNA )
Zo seems to rise as you down in freq. less so with the solid copper center cond.
FWIW, 73, W5XZ, dan
--- On Tue, 2/1/11, Jim Brown <jim@audiosystemsgroup.com> wrote:
From: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: Topband: Skin Effect of RG-6U
To: topband@contesting.com
Date: Tuesday, February 1, 2011, 12:31 PM
On 1/31/2011 3:02 PM, Dennis W0JX wrote:
> I have found that the quality, and therefore the loss, of RG-6 cable varies
> quite a bit. On the average, I measure about 14 ohms of resistance in 500
> feet if shorted at the far end. Recently, I put up a dual flag RX antenna and
> felt that the sensitivity was far down from normal. It turned out that my
> resistance was about 20 ohms for 500 feet. I discovered some oxidized
> connections in a splice and also some water contaminated aluminum shielding.
> If you are going to use long runs of RG-6, I recommend Quad with the larger
> center conductor, very careful sealing of any splices to prevent moisture,
> and if available, flooded cable to seal any pinholes.
Great advice. Also, stick to major mfrs like Belden and Commscope.
>
> I have found that the low-price Home Depot stuff has a PVC jacket which is
> easily cut and exposes the braid to moisture. The aluminum shield then starts
> oxidizing.
See http://audiosystemsgroup.com/Coax-Stubs.pdf
73, Jim K9YC
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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