The AM Forum

I am looking for a reel of RG-59 or equivalent coax rated for direct burial without conduit.  I understand that "direct burial" means, amongst other things, that the vinyl jacket is treated with some kind of additive to make it repulsive to critters that like to chew on plastic cable.  I find direct burial RG-59 listed on several websites, but wonder if anyone has any actual experience regarding which ones might be a quality product vs ones known to be crap.

Look for flooded RG-6. I think DX Engineering sells it. I use the flooded stuff and it works FB. Some have had problems with critters eating through it. I haven't.

Ive had quality name brand quad shield and flooded RG-6 and RG-11 destroyed by critters when run on the ground 700' thru the woods from the Beverage relay box. With 1/2" jacketed hardline no problems in almost 20 years. For the 100' of lawn area it was placed under the sod about 3-4" down in a slit trench. Running the RG cable up thru tree branches increased noise pickup and affected directivity as the raised radials for the phased verticals were crossing within a foot or so.

Carl
KM1H

Hi Don, My Times Microwave LMR-600db (direct burial) has been working just fine for the past 6 to 7 years I've had it in, not cheap but good. It's probably less than 1 foot deep and 350 ' long. It runs right next to a 13 wire sprinkler system wire that flips the relars at the antennas. Dave :)

Hi Don,

I'm curious what you need the RG59 for, as it is not usually all that great except for a pretty short run.  If you need it for a TV rx antenna I'd definitely do as Carl recommended and invest in some 75 ohm 3/8" heliax.  I think you can order it from Davis RF or RF Parts.  Yes it won't be cheap and you'll probably have to deal with N connectors and N to F adapters (I have one or two of those if you need them) but you'll never have to mess with your feedline again.  I also have 75 ohm heliax N males.  Actually what the heck, I have 75 ohm 1/2 inch LDF4-75 here, about 50 feet.  I can bring any or all of this to Dayton if you are interested.

Rob

This is for the beverage receiving antenna.  I need about 600' of it. For  the past several years, I have just rolled cable-TV RG-6 out on top of the ground, but something loves to chew on it.  A couple of times they actually cut a slit, just as clean and neat as if someone had used a razor blade.  The final straw was when I forgot and ran over the thing last week with the lawn mower.  That cable is now about as much patches as it is cable. I plan to bury a new one just under the sod, but I recall when I used RG-213 for the transmitting antenna, critters chewed big holes in the vinyl jacket.  I don't think that stuff was rated for burial or even for outside use.  In only a couple of years, UV from the sun noticeably deteriorated the jacket where it was exposed to daylight.

I haven't looked at the RG-214 direct burial stuff I replaced it with to see if anything has chewed on that.  I need to run a power loss test to see if it has degraded any since I installed it 4-5 years ago.

My question is, will "things" chew on cable that is rated for direct burial?  I was told that some additive in the plastic is designed to make it unpalatable to animals.  As far as hardline goes, unless it has a protective plastic cover over the metal tubing, won't soil minerals eventually eat holes in it?

What, exactly, is  "flooded" cable?

Dave, where did you buy the Times Microwave stuff?

No, I haven't put anything in the dawg house yet.  Still have some finishing touches to add to the structure, as well as finishing painting it.  Then I have to work on the layout, even though I will mostly use the same tuner components I am already using at present.  

Don
What about putting it inside of underground sprinkler tubing? The stuff is cheap and I've never seen anything chew it.
73 N8QPC

Don, it's coax with a silicone gel applied to the braid before the outer jacket is put  on. The idea is that the stuff oozes into and seals cuts in the cable jacket, keeping moisture out. I don't think it would have any effect to prevent critter damage, though. I've seen them bite right through some 3/4" PVC I have laid on the ground for the irrigation system. Cut it like with a knife, I think to get at the water.

Try looking for used or surplus 75 ohm rigid and jacketed CATV cable. Epay, perhaps? Get yourself a 500' chunk.  You can screw standard PL-259s on the ends. There's no critter that's going to chew into the stuff. I am using buried runs of surplus 1/2" Heliax for RF connections between the tower and house. Also a buried run of flooded, direct burial CAT-5 for the data connection to the 5.8 GHz microwave transceiver on the tower. Got that for free from a ham, leftovers from a data center in Texas. No DSL or TV cable out here. Internet is microwave over to Chuck, K0RF's place some 6 miles south of here.

Hi Don, I shopped around on the internet. I can't remember exact place I found the best price but I believe it was in Texas. They made up the length I wanted and also my delay line lengths (used lmr400 regular for those above ground cables) Dave

Wow Don, 600' sounds like a pretty long run for a rx antenna.  I have no direct experience with long runs and beverages but I'd be surprised if there is any signal left to detect at the end of 600 feet, even with good cable  :D

if the bev. length is not critical I'd make it longer and the coax shorter.   I know the jacket on Andrew Heliax is tough stuff.  It is thick too.  You almost have to try to damage it in order to do anything to it, but I know animals like to chew on things.  I've seen geese waddle up to small cables and eyeball them and peck at them.   Well, let's see...600 feet is not going to be cheap....I like Bill's idea of getting used CATV hardline and I'd also consider putting some kind of RF amp in the line halfway, some sort of solid state preamp to keep the signal alive--of course that means running some kind of supply voltage to it and more problems...

Rob

RG6 will show well less than 3 dB loss, even on 80 meters and less than that on 160 meters. This amount of loss in a receive antenna is insigifiant.

3 dB for how many feet?

Yep, loss is minimal and insignificant at 80/160 even with RG-6. With the 700' run of 1/2" 75 Ohm CATV hardline its even less and I sometimes use the Beverages up to 12M (probably work on 10 also) when T storms or snow static make a mess on the yagis. I have one of those 160-6M Palomar SS tuneable preamps to help on the high bands as the Beverages themselves are losing signal also since they are way too long. Its the S/N that counts.

Don, I know a guy who ran bare aluminum hardline on the ground for almost 20 years and when he moved it had barely shown any corrosion and thris was thru pine and oak woods. He said its an almost pure aluminum which is highly resistant. When its alloyed for strength then problems start.

Carl

My chart shows .35dB/100' @ 160M and .47dB/100' on 80M

Way less than 3 dB for Don's case - 600 feet.

I just finishing typing a long, old buzzard response explaining exactly why I need the 600' run, and somehow managed to hit one of those @#$%&!! mystery keys and the entire message dumped, leaving only a blank "post reply" page. I tried "going back" and reached all the way to a previous post, but the one I just typed was gone.  Whatever key I hit evidently cleaned out cache and all. >:(

I don't feel like re-doing the whole thing.  Suffice it to say I can't avoid the 600' and attenuation is not a problem.

I've had that happen to me on several occasions. I've invented at least half a dozen new cusswords over it.


FWIW, I have a big roll of white cable TV coass out in the back shed. I rescued it from a trip to the landfill. If anyone wants it, the first one that comes to get it can have it, free of charge! ! !  (I need some more room for storage)

                                                                     The Slab Bacon

Well what do you know--I learned a few new things  ;D  I am guessing the ends of the bevs are placed far away to isolate them to some extent from the tx antenna.

Yep Don, I've wiped out a few long replies hitting a wrong key--boy does it stink when that happens.

Due to layout of the land, the transmission line end of the wire is at the far end. I lease cropland and have to take down part of the antenna during growing season, so a two wire beverage set up to feed at the forward end of the wire is out of the question.  Taking down and putting up a two wire system would be way too much work to perform twice a year.

Don, I have RG-59B/U which is supposed to be direct burial coax with a jacket that has a silicone rubber "feel". I don't have a reel but I have a total of 554' feet in 4 unused odd lengths (78' + 90' + 140' + 246').  It has a copper stranded center conductor rather than the typical solid conductor so standard F connectors cannot be used with it.  You are welcome to it if it is helpful to you.  I have absolutely no need for it and would love to see it put to good use.  If interested, please email me directly: wb2cau@gmail.com

Eric

Don, I found another 3 lengths of approx 25' each, so there's over 625' feet total.  If you don't mind splicing lengths together, you're in business.  I'll mail you a 6" sample of the stuff if you want.

Eric

Thanks, but I prefer a single unspliced piece since I plan to bury the entire thing.  I have tried splicing my buried transmitting feed line on more than one occasion, and every time, despite my best efforts using a variety of products, water still managed to make its way inside.

I'll bury most of it just below the sod, except where it goes across the cultivated field, where I plan to bury it deeply enough that farm tilling equipment won't touch it.

Ultimately, the buried transmitting co-ass will be replaced with open wire feeders above ground from the tower all the way to the  shack.

Here's an idea.

You can make a simulated coax line from five insulated open-wire feeders. One in the center, and four in a box around the center. Extremely low loss, will take a gazilion watts, even 6" spacing between conductors would be fine on 160-40. We still have the 1950s remnants of same out at one of our 50KW AM stations. The #6 center conductor on power line insulators and four conductors around it on wood X crosses. All on 20' wood poles between the transmitter, the ATU and the stick.

If you still have a lot of that copperweld, it might be worth trying.

I have thought of that for the transmitting feedline, but I think I'll stick with balanced two-wire line.  The long run of beverage receiving feedline needs to be buried, away from the farm activity, lawnmowers and other surface traffic.  If I knew for sure the rodents or whatever it is would leave it alone, I would simply purchase a 1000' spool of direct burial RG-59 and bury it in the ground.  I just don't want to go to all that expense and do all that work only to find a year later that something has chewed up outer jacket and allowed the cable to become contaminated. I want to be sure my "direct burial" cable is really satisfactory for burying in the ground.

The phone company buries plastic covered twisted pair directly in the ground all the time and nothing chews up the insulation, so I know such material exists, but I don't trust advertisements and manufacturers' claims without some verification from actual experience.

Don,

The only direct burial I have used is Times Microwave LMR-400DB which is RG-8 sized 50 ohm coax.  I buried 125 feet of it to my Hy Tower vertical and it has been in place for around 10 years without any issues. 

Soldering a coax connector to it was a major pain.  It is impregnated with waterproofing material and I went through a number of solvents before finding anything that would clean the shield well enough for it to cleanly take solder. 

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

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
KM1H

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.

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.

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
N4LTA

I'm interested.  Just about any coax would work with the beverage if I suspend it off the ground, 50Ω or 72Ω.  Thanks.

 All is not safe with hardline......

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


klc