1/12 wave at what frequency?
Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Bob Pack, NX5M
Sent: Friday, October 29, 2004 11:08 AM
To: Tim Holmes; towertalk@contesting.com
Subject: Re: [TowerTalk] Cable TV hardline question
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
> >
> >
> >
> _______________________________________________
>
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>
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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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_______________________________________________
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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