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Re: [TowerTalk] Rotator loops

To:, "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] Rotator loops
From: jimlux <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Sat, 27 Feb 2010 06:33:57 -0800
List-post: <">>
Pete Smith wrote:
> I notice that typical ham rotator loops involve an unsupported loop that 
> is perpendicular to the mast, and attached at top and bottom.  It seems 
> to me that this means a lot of flexing through 360 degrees, and in the 
> wind.  I have also noticed that TV station remote trucks seem to use 
> another solution for their rotating dishes - they wrap a few turns of 
> coax loosely around the mast, so that a one-turn rotation only slightly 
> loosens or tightens the wrap.  Seems like this would be a better, more 
> durable practice for ham installations too.
I agree.. they also do this to accommodate the big difference in height 
as the mast extends, so the coax neatly stacks as it comes down.

But, ZOMG,(<grin>) adding each loop of coax (if about 4 feet in 
diameter) adds 10-12 feet of coax, and at $.50/ft, that's $5 per extra 
wrap. And what about the loss? Each of those turns adds 0.05dB at 10 MHz

(actually,all joking aside, if you were on 10m, the loss might be 
something to contemplate.. an extra 10 turns would start to add up, 
although antenna gain on 10m is pretty easy to come by.. making up the 
dB of coax loss is probably not tough)

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