Topband: underground cables question

Thu Oct 5 08:49:31 EDT 2017

I agree with Ken, with only one option, and that would be if the conduit is open on both ends.. allowing free air flow thru. That situation, MAY help dry the water from sitting on the cable, depending on the average humidity at the underground temp. Warm air from inside.. to cold air outside may not work out well either.

Have a great day,
--... ...-- Dale - WC7S in Wy

"Actions speak louder than words"
1856 - Abraham Lincoln

________________________________
From: Topband <topband-bounces at contesting.com> on behalf of Ken Claerbout <k4zw at verizon.net>
Sent: Thursday, October 5, 2017 6:19 AM
To: topband at contesting.com
Subject: Re: Topband: underground cables question

As you have found out, it's impossible to keep water out of a conduit like that.  I use direct bury cabling and put it directly in the ground.  Granted the cable is flooded, but putting in back in the conduit ensures it will sit in some water, something I would try to avoid.

73
Ken K4ZW

-----Original Message-----
From: John <beaumonts at beaumonts.karoo.co.uk>
To: topband <topband at contesting.com>
Sent: Thu, Oct 5, 2017 4:11 am
Subject: Topband: underground cables question

Hi all, some  years ago I buried a 4 inch conduit about a foot deep in my field , inside I run a control wire and a coax line RG213 to a 160 m vertical the feeder was a total of 5/4 wavelength long about half of it in the conduit, it was used as one line for a pair of verticals spaced 5/8 wave apart. When first installed it worked very good but after a while I noticed it dropped off and I suspected water ingress. An insulation test with 1000v from my electricians test equipment showed indeed a fall in insulation resistance.

So my question is I have a couple of large reels of commscope F1160 BEF flooded 75 ohm
do you think I could put it in the same conduit which has allowed some water in or would you make alternative arrangements . I realise it a direct bury coax but appreciate advice.

I wish to get the two verticals going again will use 1 X 3/4 line above ground 1x5/4 line part in conduit and a 1/2 wave to switch in and out above ground.

regards

John Beaumont
G4EIM

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