[Antennas] Underground open wire feeders

Thu, 16 Oct 2003 06:02:11 -0700

 One thing more-- I'd avoid  9913- type hollow coax like the plague.
it *WILL* eventually fill with water. I have two 150 foot runs in the ground
now that became unusable after a few years because they did.

73  Dick W0EX

>Message: 1
>Date: Tue, 14 Oct 2003 07:58:18 -0700
>From: Dick Carroll <[email protected]>
>To: [email protected]
>Subject: [Antennas] Re: Antennas digest, Vol 4 #245 - 12 msgs
>
> Tom, your problem will be keeping out the water, especially so in Oregon.
>I once worked where we used a radio system remoted through underground 
>metal
>pipe (rigid, not conduiut) which was sealed-screwed together same as 
>water pipe) ane
>commercially sealed with an appropriate  plastic resin sealant at each 
>end exit. And still, it
>filled with water. How it did it I never could determine. But with time, 
>we had to replace the entire
>cable system,  with newly installed conduit (we used 4inch schedule 40 
>PVC this time so that new cables could be easily pulled)..
>
>
> As to your situation- I'd consider using a very low loss coaxial cable, 
>twin runs as you
>noted, only I'd get something like hard line or fairly large diameter 
>rubber coated  TV
>cable trunk line. Of course you'd have to install the cable in the 
>conduit as you buried it
>since you  couldn't pull the hardline through installed conduit. But a 
>reasonably short run
>woiuldn't seem to degrade your signal enough to worry about.
>
>If you're sure to have water enter the conduit, and I'm convinced it 
>will, then installing
>twin lead as you describe will prove to be an exercise in futility.
>
>Dick W0EX
>
>  
>
>>Message: 2
>>Reply-To: <[email protected]>
>>From: "Tom Scott" <[email protected]>
>>To: "Antennas Reflector List" <[email protected]>
>>Date: Mon, 13 Oct 2003 15:08:57 -0700
>>Subject: [Antennas] Buried ladder line?
>>
>>Okay, this is really a serious question, despite the seeming
>>contradiction in the title. 
>>
>>Has anyone ever considered running ladder line underground through large
>>diameter ABS tubing? It seems like you could add spacers (maybe
>>margarine tub lids) to keep it centered? I need to go a short distance
>>    
>>
>>from my shack to a tower but it crosses a driveway and I hate to put it
>  
>
>>up in the air. I will be digging a trench anyway for the rotor cable and
>>some control wires and probably some coax as well. I can easily get 5 or
>>6 inch abs pipe and figure that ought to provide enough air spacing from
>>the ground to minimize loss. Bends are a little bit of hassle, but it
>>seems like there are a couple ways to deal with this. My case is almost
>>a straight shot anyway, except for down into the trench and back up
>>again.
>>
>>This would be sort of like giant air-core twin-ax.
>>
>>I'm not interested in proposals that involve burying pairs of coax; yes
>>that can maintain balance, but is lossier with a mis-match than ladder
>>line.
>>
>>Thanks!
>>
>>- Tom Scott
>>27005 SW Neill Rd
>>Newberg, Oregon 97132
>>503-330-6867 - Cell
>>503-538-5839 - Home
>>503-554-9468 - Fax
>>KD7DMH
>> 
>>
>>    
>>
>
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