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Re: [TowerTalk] Cable TV hardline question

To: "Tim Holmes" <>, <>
Subject: Re: [TowerTalk] Cable TV hardline question
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Fri, 29 Oct 2004 09:59:07 -0400
List-post: <>
> I also came up with some Cable TV hardline.  Its 1/2 inch
(I think) -
> Jacketed in PVC with an Air Dialectric.  I have been
looking for ways to
> connect it for my VHF / UHF antennas.  Also I am concerned
about the
> impedence mismatch.

I would be concerned also, since the cable can cause an SWR
of over 2:1 at the radio.
Most VHF and UHF radios do not tolerate such a high SWR this
very well.

What you can do is build a transformer using lengths of 50
and 75 ohm cable mixed. It is pretty tricky to do this at
UHF, but it can be done if you have the test gear and are
careful. I don't have references, but I'd bet someone else
does. The devices are called non-synchronous transformers.

I certainly look into matching the cable at VHF or UHF, not
because of cable loss but because of bandwidth and impedance
problems at the radio. A 2:1 SWR is not good for most

73 Tom


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