Tom,
Lets assume your total coax cable length is 500 feet from your transmitter, out
to your tower, up the tower, then to the C31XR feedpoint.
Here are the loss figures in feet per dB for various common coaxial cables:
CABLE ATTENUATION (feet per dB)
14.0 21.0 28.0
LDF5-50A 714 588 526
3/4" CATV 769 588 435
LDF4-50A 588 400 323
9913 220 190 155
RG-213 130 100 83
As you can see, RG-213 would have just over 6 dB of loss on 10 meters, and
nearly 4 dB on 20 meters. You would do about as well with a dipole immediately
next to your house! Even 9913 has over 3 dB of loss on 10M and almost 2.5 dB
on 20M. However... notice that good old 3/4 inch 75 ohm CATV cable performs
really well, with slightly over 1 dB of loss in your situation. If you're a
purist, you could purchase 500 feet of Andrew LDF5-50A, but that would set you
back about the same amount as your tower and beam!
73!
Frank
W3LPL
---- Original message ----
>Date: Wed, 16 Aug 2006 20:55:40 -0400
>From: "Tom Crothers" <TCrothers@columbus.rr.com>
>Subject: [TowerTalk] Antenna Distance From Shack
>To: <towertalk@contesting.com>
>
>Hello Fellow Tower Talkians,
>
>I'm placing a 65 ft. tower with a C31XR on top, approximately 400 ft from my
>shack in the house. I've always used RG-213 or RG-8U in the past to this
>Yagi, (but I've never had the tower that far away before either). Anyone
>see a problem continuing to use the same coax with that distance?
>
>Thanks,
>
>Tom
>K8ANA
>
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