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RE: [TowerTalk] Cable TV hardline question

To: <towertalk@contesting.com>
Subject: RE: [TowerTalk] Cable TV hardline question
From: "Keith Dutson" <kjdutson@earthlink.net>
Reply-to: keith@dutson.net
Date: Fri, 29 Oct 2004 12:42:31 -0500
List-post: <mailto:towertalk@contesting.com>
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
> >
> >  
> >
> _______________________________________________
> 
> 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.

_______________________________________________
TowerTalk mailing list
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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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