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eHam Forums => Station Building => Topic started by: KC2KMJ on July 09, 2011, 03:57:26 PM



Title: RG-213/u: direct burial?
Post by: KC2KMJ on July 09, 2011, 03:57:26 PM
I need rougly 90' of coax for my HF antenna install. I've tried to determine if the RG-213/u "MIL-C-17" determines burial but haven't been able to confirm. Is "RG-213/u" direct burial or does it need to directly state this? I was considering Davis 9914F but then found out it's foam dielectric and I've had bad experiences in the past with foam. I can get 213/u (MIL-C-17) locally for a good price but was wondering about direct burial application. Thanks.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 09, 2011, 04:51:14 PM
I have a run that has been buried for 15 years now. It is pretty tuff stuff and as long as it is not rocky soil that could damage cable it will be fine.


Title: RE: RG-213/u: direct burial?
Post by: KC2KMJ on July 09, 2011, 06:05:08 PM
John, does/did your cable indicate anything about being direct burial?  I've seen 213 with that printed on there and others that don't.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 09, 2011, 06:40:48 PM
Mine is from a roll of new surplus Mil Spec 213 I bought about 20 years ago.(it came from a gov supplier and was real mil spec 213) I still have some around that has never been used and still looked great last time I saw it but I do not have it handy at moment to tell you what it says on it. (I am not in shack either) Sometimes you can find some RG 393 which is a double shielded RG8 type cable with a very tuff jacket and teflon dielectric. Good stuff if you can get your hands on it. The RG 58 version is called RG 142


Title: RE: RG-213/u: direct burial?
Post by: K9KJM on July 10, 2011, 10:00:42 PM
It is always a very good idea to put any type of coax used inside some type of "conduit" instead of direct bury. For lots of reasons.   The "conduit" does not have to be actual expensive conduit, But any type of cheap low cost plastic pipe.   Corrugated 3 and 4 inch diameter drainage pipe sells in the 20 some dollar range for a 100 foot long roll.
Very cheap insurance. Put a pull string in it right away and you can always pull more coax through in the future if wanted.   Also, While the trench is open, Be SURE to also lay in a bare copper wire or copper tube OUTSIDE the conduit to bond your ground systems together, And to add to your overall ground system.



Title: RE: RG-213/u: direct burial?
Post by: K1CJS on July 11, 2011, 05:17:54 AM
I would second "KJMs answer.  It is ALWAYS better to do a job once and be done with it.  Putting a cheap conduit in place is wise for more than one reason.  If you want to run more cables or run a rotor control cable one day, you won't have to dig again.  And, if the co-ax developed problems, it is far easier to pull it out to check it than it is to dig it up.

You may have your reasons, but the smarter, easier and far better way to lay underground lines is to put them in a conduit.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 11, 2011, 07:42:29 AM
It is amazing how many can take a simple job of slicing damp ground and pushing in some direct burial 213 and make in complicated. Conduit is not needed here and can bring its own problems. It can fill with water over time and limits routing options as well to name a few. The conduit will cost you more than coax too. (and how much more depends on size of it)

BTW I dug out my old roll of 213 and it says "Times Wire and Cable Company Inc    Mil Type    RG-213/U" on coax.


Title: RE: RG-213/u: direct burial?
Post by: K8KAS on July 11, 2011, 08:24:23 AM
I used the RG213 on the ground for years with no trouble, but when I put coax a few years ago inside PVC pipe I had water in the PVC and trashed the coax in a year. The pvc was very well sealed at both ends with RTV. The nice thing on the RG213 on the ground it sort of melted into the sand/ground in 6 months and you could not see it. No pipe for me again...Denny K8KAS


Title: RE: RG-213/u: direct burial?
Post by: WB2WIK on July 11, 2011, 09:16:26 AM
I need rougly 90' of coax for my HF antenna install. I've tried to determine if the RG-213/u "MIL-C-17" determines burial but haven't been able to confirm. Is "RG-213/u" direct burial or does it need to directly state this? I was considering Davis 9914F but then found out it's foam dielectric and I've had bad experiences in the past with foam. I can get 213/u (MIL-C-17) locally for a good price but was wondering about direct burial application. Thanks.

MIL-C-17 is just the general specification for cables.  It doesn't imply anything other than it was manufactured by a Qualified Product List supplier.

"Direct burial" cable is a special design that is self-repairing if pierced.  To do that, during the manufacturing process a tar-like substance bonds the outer jacked to the outer conductor (shield) of the cable, making the cable a bit more difficult to strip and work with.  The stuff is sticky and makes a mess, but it serves a purpose.  If you can install the cable so that it is never pierced by anything (including the sharp teeth of critters outside!), it shouldn't matter if you use "direct burial" cable or not.  I've used regular high-quality RG-213/U buried slightly beneath the soil lots of times, often for several years, with no issues.  The issues I've had are mostly above ground, where rodents can chew on it!


Title: RE: RG-213/u: direct burial?
Post by: K1CJS on July 11, 2011, 09:34:04 AM
I used the RG213 on the ground for years with no trouble, but when I put coax a few years ago inside PVC pipe I had water in the PVC and trashed the coax in a year. The pvc was very well sealed at both ends with RTV. The nice thing on the RG213 on the ground it sort of melted into the sand/ground in 6 months and you could not see it. No pipe for me again...Denny K8KAS

You didn't put drain holes in the PVC--or use a conduit that had drain holes in it already?  Didn't have any gravel under it either, huh? No wonder you had problems.  If you don't do a conduit installation right, it isn't worth doing at all.  

Another thing--if you live in an area where the ground freezes during the winter, just pushing coax into the ground a couple of inches isn't going to be conducive to making the coax last longer either.  Frozen ground can be just like a knife to coax if something heavy goes over it.  In any event, if you do the job once and do it right, you'll never be sorry.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 11, 2011, 11:21:06 AM
You didn't put drain holes in the PVC--or use a conduit that had drain holes in it already?  Didn't have any gravel under it either, huh? No wonder you had problems.  If you don't do a conduit installation right, it isn't worth doing at all.  

Over rated and not needed. I have a 175 foot run of 8/3 UF that I just threw in trench with water line going to barn 25 years ago. No conduit, no problems. I regret not throwing some RG 213 in trench too.

Another thing--if you live in an area where the ground freezes during the winter, just pushing coax into the ground a couple of inches isn't going to be conducive to making the coax last longer either.  Frozen ground can be just like a knife to coax if something heavy goes over it.  In any event, if you do the job once and do it right, you'll never be sorry.

Well I live were temps have been as high as a 100 or so (97 right now) and as cold as 28 below and my coax has never failed in ground or in grass. Frozen ground is not going to do squat to cable unless it is maybe real rocky. Some like to make a major project out of a minor one.


Title: RE: RG-213/u: direct burial?
Post by: K1CJS on July 12, 2011, 10:27:52 AM
....Some like to make a major project out of a minor one.

Touche--but the opposite is true also.  Some like to do a project time after time because of changes or additions, while if you do it right the first time, you'll never have to do it again.

As you also said--

Quote
I have a 175 foot run of 8/3 UF that I just threw in trench with water line going to barn 25 years ago. No conduit, no problems. I regret not throwing some RG 213 in trench too.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 12, 2011, 11:03:05 AM
Touche--but the opposite is true also.  Some like to do a project time after time because of changes or additions, while if you do it right the first time, you'll never have to do it again.

But using conduit does not promise no problems and no rework needed. So doing it right is a matter of point of view at times. Conduit near surface by nature will have frequent temperature swings and pressure changes because of it which will tend to draw moisture that can collect in conduit over time. If you really want to use it it would do better either below frost line or with positive venting to keep moisture out.



Title: RE: RG-213/u: direct burial?
Post by: WB2WIK on July 12, 2011, 02:05:25 PM
Anecdotally, most of the problems I've had with coax occurred above ground, not below it.

That's because the squirrels and such don't live below ground and some like to snack on coax.

Moles do live below ground and have sharp teeth but haven't given me many problems like the above ground critters have.


Title: RE: RG-213/u: direct burial?
Post by: K1CJS on July 12, 2011, 05:16:54 PM
But using conduit does not promise no problems and no rework needed. So doing it right is a matter of point of view at times. Conduit near surface by nature will have frequent temperature swings and pressure changes because of it which will tend to draw moisture that can collect in conduit over time. If you really want to use it it would do better either below frost line or with positive venting to keep moisture out.

Exactly the point that I'm making here.  A rework is much easier and less time consuming if the coax and other lines ARE in conduit.  Doing the installation with conduit does take more time and money the first time, but you'll never be sorry, especially if you have the need to pull more cables in the future--or if you need to pull back a cable because of a fault.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 12, 2011, 05:49:05 PM
Exactly the point that I'm making here.  A rework is much easier and less time consuming if the coax and other lines ARE in conduit.  Doing the installation with conduit does take more time and money the first time, but you'll never be sorry, especially if you have the need to pull more cables in the future--or if you need to pull back a cable because of a fault.

When ground is damp/wet using a square blade shovel you can slit open ground 6 inches at a time and lay in cable and tamp it shut at a rate of several feet a minute with a little practice and be done in a matter of minutes. It cable goes bad it is easy to remove or leave it in place. If you are running several cables to one place maybe a conduit makes sense but for one or two going same way direct burial is good. Also with direct burial you can run to several locations without digging trenches all over yard and a few days time too.


Title: RE: RG-213/u: direct burial?
Post by: K9KJM on July 12, 2011, 10:12:31 PM
The 3 and 4 inch diameter corrugated plastic drainage pipe I mentioned that sells for 20 some bucks for a 100 foot roll comes in both solid and PERFORATED for the same price.  So if you are worried about moisture or water build up, Just get the perforated stuff.  Most any farm and fleet type store will have it in stock. 
Small sharp stones WILL damage coax jackets in the freeze/thaw cycle around here. So will the wife digging a hole to plant flowers.  Lots of us learned the hard way that in the end, It is better to put the coax inside some kind of conduit.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 13, 2011, 01:01:05 PM
The 3 and 4 inch diameter corrugated plastic drainage pipe I mentioned that sells for 20 some bucks for a 100 foot roll comes in both solid and PERFORATED for the same price.  So if you are worried about moisture or water build up, Just get the perforated stuff.  Most any farm and fleet type store will have it in stock. 
Small sharp stones WILL damage coax jackets in the freeze/thaw cycle around here. So will the wife digging a hole to plant flowers.  Lots of us learned the hard way that in the end, It is better to put the coax inside some kind of conduit.


That pipe will crush if not buried deep if run over by a car. I would use something smaller and stronger if i wanted to use conduit.


Title: RE: RG-213/u: direct burial?
Post by: K1CJS on July 14, 2011, 04:27:03 AM
The 3 and 4 inch diameter corrugated plastic drainage pipe I mentioned that sells for 20 some bucks for a 100 foot roll comes in both solid and PERFORATED for the same price.  So if you are worried about moisture or water build up, Just get the perforated stuff.  Most any farm and fleet type store will have it in stock.  
Small sharp stones WILL damage coax jackets in the freeze/thaw cycle around here. So will the wife digging a hole to plant flowers.  Lots of us learned the hard way that in the end, It is better to put the coax inside some kind of conduit.

That pipe will crush if not buried deep if run over by a car. I would use something smaller and stronger if i wanted to use conduit.

That type pipe will not crush easily unless you run over it while its above ground, and coax will get crushed long before that corrugated pipe will if you only bury it a couple of inches below a driveway's surface..  The corrugations in that drain pipe prevent that from happening.  That pipe is originally meant for water drainage, and anything so meant isn't going to give 'way under the pressure of a car--and its usually buried down deep enough so that it won't freeze and will allow water to drain away.  In any event, most people don't drive cars over the lawn, nor run cabling under a driveway.  If you do and don't think about that beforehand you deserve what you get.

You do it your way and we'll do it ours, John.  Don't try to convinve us that your way is better, because it isn't--for several reasons.  I'm done here--I am not going to waste my time arguing with you any longer.  73.  


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 14, 2011, 06:20:57 AM
You do it your way and we'll do it ours, John.  Don't try to convinve us that your way is better, because it isn't--for several reasons.  I'm done here--I am not going to waste my time arguing with you any longer.  73.  

     Well Chris some of us have  lived in country for 30 year and have buried a LOT of things (like drain lines, water pipes, leach fields and what have you).  The pipe in question being discussed here is drain tile and it WILL collapse if near surface and run over with a heavy vehicle, I have seen it. It is meant to be buried much deeper. The version with holes is used as drain tile or leach field runners but in both applications they are buried much deeper and better protected. The solid version is for interconnects. The ribbing it to prevent collapse when being buried in ground, not against cars never surface. Heck a decent riding mower will crush pipe laying on ground.  I have also see shrub roots go through it and plug it up more than once as it is not as strong as you imply. I have never seen white PVC damaged from drive over or root.

Of course you do not want to waste you time because you are wrong here but will never admit it. Moral is either go direct burial or PVC if you want a conduit. If you want to use drain tile either bury it deep were no tree or shrubs are present or make sure you never drive over it.  BTW you can run 213 over with a mower and cars just laying in yard time after time and not hurt it not so with drain tile.


Title: RE: RG-213/u: direct burial?
Post by: N0YXB on July 14, 2011, 10:14:44 AM
I don't believe it's a matter of right and wrong, but a matter of what works for your circumstances.  I've got corrugated plastic drainage pipe buried 6-8 inches underground that I've occasionally driven over without crushing it.   


Title: RE: RG-213/u: direct burial?
Post by: W8JI on July 14, 2011, 11:34:05 AM
I have about 2000-3000 feet of various pipes in the ground. I have never had a problem with the corrgated drain pipe crushing unless I crush it during install. I bury it about 18 inches deep minimum. As a matter of fact someone is in the backyard trenching right now and asomeone else is at the store picking up 250 feet of unperforated corregated. I'll put T's at 1/3 and 2/3 distance and drill holes at the low spots in the pipe bottom only, and lay rock below at the low areas.

http://www.w8ji.com/contest_station_w8ji.htm



I drive tractors and my F250HD diesel across pipes all the time, and two cross my stone driveway.

What you cannot do is tamp the soil with something or step on the pipe until it has at least six inches of packed dirt. For example I have crushed it by getting my tractor front tire in a fresh trench because I lined the wheel up with the trench before it had much dirt in it. Once there is a foot of dirt I can cross it any angle.

I have some thinner wall plastic drain pipe like for septic systems, too. It is easier to pull long cables through, and a little tougher. Maybe 5 or 8 of them between 50 and 300 feet long. 

I advise, no matter what type of pipe, having drainage at the low spots. If the spot is always wet then a sealed pipe with forced air venting might be necessary, or use hardline and flooded direct burial cables and just let the water pile up.



Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 14, 2011, 11:46:08 AM
I don't believe it's a matter of right and wrong, but a matter of what works for your circumstances.  I've got corrugated plastic drainage pipe buried 6-8 inches underground that I've occasionally driven over without crushing it.   

6 to 8 inches will work most of the time in somewhat firm ground but that means a trench 10 to 12 inches deep so top of pipe is 6 to 8 inches under surface. Depth is more critical in damp ground than firmer ground.


Title: RE: RG-213/u: direct burial?
Post by: W8JX on July 14, 2011, 11:52:43 AM
I have about 2000-3000 feet of various pipes in the ground. I have never had a problem with the corrgated drain pipe crushing unless I crush it during install. I bury it about 18 inches deep minimum.

And at 18 inch minimum you will not have problems (except maybe soft ground and a cement truck hi hi) It is not to be viewed as a pipe that you dig a shallow trench and cover it up and roll. The ribbing on the tube is to prevent it from crushing under weight of dirt on it when buried deep and back filled. Once dirt sets around the the form of the pipe it basically carries load around pipe when buried deep enough unless it is very mushy.