Wow, what great responses from so many on and off-line. Thank you all those
who helped think this through. As I mentioned in the original post, I have
been using the cable for VHF/UHF for some time and don't have any problems
making up the ends to be PL-259 or N-connectors. I seal the ends with a tight
wrap of electrical tape then apply a thick layer of outdoor grade Silicon RTV.
What's great about the RTV is, that if needed, it can be peeled off in just a
few minutes. I have had connections like this outside for years so far without
any signs of degradation even at 70cm.
But, regarding the mismatch between 50 and 75 ohms, if on all bands my antenna
were a 1:1 (at 50 ohms) I would not have worried about the immediate jump to
1.5:1 or the extra loss created by such. My antenna at best is around 1.5:1
and near the band edges gets higher than that. My concern was the added SWR to
this when using the 75 ohm cable. I do not own a high power tuner and just
purchased a legal limit amp and do not want to experiment tuning it into a
possibly high SWR. My rig of course has a built in tuner so lower power
operation would have been no problem.
I had considered the 1/2-wave principal early on but did not take it far
enough. I considered a 1/2-wave working on 20m and on 10m but not on 15m.
However, as several had mentioned, if the cable is made longer, like when the
primary frequency is made to be 40m or lower, then all three bands can be made
happy. That's the trick I was looking for. I want to thank everyone for
taking the time to share thoughts and ideas.....this is a great group of people
!!!
Hope to see you on the air soon. Oh, BTW, found the problem with the HAM-IV
rotor.....I faulty limit switch. Rotor is back together and soon to go up the
tower. I should be QRV this afternoon.
73,
Gedas, W8BYA
e-mail w8bya@mchsi.com
online gallery http://gedas.cc
web page http://www.w8bya.com
----- Original Message -----
From: David Robbins K1TTT
To: towertalk@contesting.com
Sent: Sunday, June 05, 2005 6:03 AM
Subject: Re: [TowerTalk] Using 75 Ohm Hardline
First, forget the impedance mismatch, for hf use it is absolutely
insignificant. Then follow the comments some others have made about using
plumbing fittings to make your own connectors, cover them with lots of duct
seal available cheap at the same hardware stores and enjoy them for years to
come.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> -----Original Message-----
> From: towertalk-bounces@contesting.com [mailto:towertalk-
> bounces@contesting.com] On Behalf Of Gedas
> Sent: Sunday, June 05, 2005 01:29
> To: towertalk@contesting.com
> Subject: [TowerTalk] Using 75 Ohm Hardline
>
> Hi everyone. I was wondering if someone could recommend an easy and
> elegant method that would allow me to use a bunch of 7/8" 75 ohm hardline
> I have. My antennas on 2 of 3 towers require over 270' runs and I would
> like to use this very nice hardline. On VHF and UHF I built custom 1/4
> wave transformers which have worked perfect for years but for my tribander
> that approach will obviously not work. Any ideas?
>
> 73,
> Gedas, W8BYA
>
> online image gallery at http://gedas.cc
> e-mail address at w8bya@w8bya.com
> web page at http://www.w8bya.com
> _______________________________________________
>
> 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
_______________________________________________
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
_______________________________________________
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
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