Re: [TowerTalk] Cable TV hardline question

[Mike <k4gmh@arrl.net>]

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.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

        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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