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Re: [TowerTalk] Cable TV hardline question

To: Tim Holmes <W8TAH@Zoominternet.net>, towertalk@contesting.com
Subject: Re: [TowerTalk] Cable TV hardline question
From: Mike <k4gmh@arrl.net>
Date: Fri, 29 Oct 2004 14:45:32 -0400
List-post: <mailto:towertalk@contesting.com>
Hello Tim,

The 50 to 75 Ohm transmission line transformer (TLT) described by Sevick work well. Used a couple of homemade TLTs (one at each end of a 200 ft run of CATV hardline) with 1500 Watt RTTY and they survived. They were used for HF for 80 thru 10 meter antennas.

At 12:08 PM 10/29/04, Bob Pack, NX5M wrote:
Build 1/12th wave coaxial transformers on each end.  Easily done if you are
not happy with the swr.  My last install for a 20m stack was almost 300
feet of the 3/4" catv with trannys on each end.  Tested into a dummy load I
could find no swr to speak of.....and the swr after all the antennas were
up in my worst case combination is no higher than 1.3:1.  I might add that
I am also using 1/2" catv from the phasing/switchbox to the tail of RG213
connected to the antennas.

GL
Bob NX5M

On Fri, 29 Oct 2004 11:33:28 -0400, Tim Holmes <W8TAH@Zoominternet.net>
wrote :

> Yeah, thats what I was worrying about-- If anyone has any good
> suggestions, I would love to hear them,  I hate to have this stuff just
> sitting around, not doing anything.
>
> Tim
>
> >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
> >radios.
> >
> >73 Tom
> >
> >
> >
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
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>
>
>
>
_______________________________________________

See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

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73,
Mike, K4GMH



_______________________________________________


See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

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