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Author Topic: Direct Burial RG-59 cable  (Read 3695 times)
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K5UJ
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« Reply #25 on: April 27, 2010, 12:33:20 PM »

Don, I think this is your problem:  You are looking for "direct burial" line but your problem is really finding a line with the ruggedness to withstand animal contact.  "Direct burial" only means the jacket is made to resist breakdown from contact with soil and there is some attempt at waterproofing to keep the dielectric from wicking up water.  None of this guarantees the feed can stand up to a mole chewing on it.  In fact, some of the direct burial line has jackets that are made of soft chewy plastic. 

This place has some Andrew RG11 direct burial https://www.mjsales.net/items.asp?FamilyID=861&this_Cat1ID=266&Cat2ID=34&Cat3ID=27  but again, it is probably not what you really need.

What it boils down to is if you want professional grade reliability, you are going to have to bite the bullet and spend the money on real professional/commercial grade feedline.   If it were me, I'd start getting prices on 1000 feet of 3/8 inch Andrew heliax.

There are three things it has going for it:  1.  Heliax has the toughest jacket I have ever seen.  It is almost like a PVC pipe for a jacket.  2.  If the jacket does get breached, the shield is solid corrugated copper.  The dielectric is still protected by the solid shield -- in fact the line would work fine electrically with no jacket at all.  3.  If any of this fails, and you do have to make a repair, the splice will be made with Andrew connectors.  These are waterproof and the only soldering is with the center pin on each male.  A couple of N males and a N bullet between them and you are back in business. 

I really can't think of any other coax cable solution for animals, other than buying less robust cable and putting it in PVC pipe but that would probably be a lot more work and expense than just getting heliax.

Another option is to bury so deep (a few feet) that you get below the below grade region where most animals burrow.   But now we're talking about trenching 600 feet and if you have anything go wrong down there you have another problem (usually when radio stations run deep feedline, it is in a big pipe with a few pull lines so they don't have to excavate and have plenty of room to pull another line).

Rob
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« Reply #26 on: April 28, 2010, 08:20:24 AM »

Im pretty sure that 1/2" CATV jacketed hardline is a lot cheaper than Andrew. In some areas you can buy a reel right from a CATV installation outfit at their quantity discount. UHF or N adapters are easy to fabricate and waterproof, no impedance bump worries at HF.

Carl
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k4kyv
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« Reply #27 on: April 28, 2010, 03:53:54 PM »

I have about decided to abandon the idea of burying the cable.

I use a run of mil-spec direct-burial RG-213 between my transmitter and antenna tuner.  Decided to check it out yesterday, with 100 watts and dummy load.  The load shows 1:1 SWR on 75m, so I attached it to the tower end of the RG-213.  Placed an average-reading wattmeter between transmitter and RG-213, and adjusted power to exactly 100 watts.  Then moved the wattmeter to the far end, between RG-213 and dummy load, and had only 75 watts.

The first line I used, which was doubly shielded silver plated RG-214, dropped from 93% efficiency to something like 80% after about 10 years, and that's when I discovered something had chewed holes in the jacket.  This time, with the RG-213, the efficiency has dropped even lower, and I am not sure it has even been 10 years since I replaced it.

I think I still have enough 213 on the spool to replace what I am now using, but I am going to put up some poles and run it above ground as a temporary measure until I can get the open wire line working.  I'll just go ahead and put up the poles for the open wire, and temporarily use them to suspend the coax until I can complete the project.

I am thinking of making up a set of portable tripods out of PVC pipe to suspend the beverage feedline off the ground over the winter.

I think moles may be the culprits; in recent years they  have pretty well kept the entire lawn and garden ploughed up with their tunnels.  I surrounded the veg garden with castor bean plants last year to keep them out of there, and I believe it might have helped, but that wouldn't be a solution for the antenna problem.
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Don, K4KYV                                       AMI#5
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« Reply #28 on: April 28, 2010, 04:11:17 PM »

Don, have you ever thought about burying PVC pipe then running the coax through it for protection?
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k4kyv
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« Reply #29 on: April 29, 2010, 10:00:44 AM »

900 ft. would be pretty expensive.  Plus it would fill up with water from  condensation even if there were no leaks, so the coax would have to be rated for direct burial.  I have a couple of used rolls of that black flexible stuff, but don't think 900 ft. It would take a lot less PVC to make the tripods, but then there is still the hassle twice a yeor of deploying the cable and reeling it back up.

As badly patched up as that old cable is, I  still got enough signal from the beverage that I did not  have to use a pre-amp.  In the worst case I  could still patch it and use it another season or two.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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N4LTA
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« Reply #30 on: April 29, 2010, 10:47:15 AM »

Don,

I may have 500-1000 ft - most of a spool that you can have for shipping. Let me know and I will cut you a sample. I bought it for a beverage years ago.

Pat
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k4kyv
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« Reply #31 on: April 29, 2010, 06:41:49 PM »

I'm interested.  Just about any coax would work with the beverage if I suspend it off the ground, 50Ω or 72Ω.  Thanks.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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KB2WIG
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« Reply #32 on: April 30, 2010, 11:51:55 AM »

 All is not safe with hardline......

http://www.radioworld.com/article/99672


klc
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