[TowerTalk] Antenna Distance From Shack

[donovanf at starpower.net]

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 at columbus.rr.com>  
>Subject: [TowerTalk] Antenna Distance From Shack  
>To: <towertalk at 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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