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Burying Coax Feedlines & Control Cables
I have a 64 foot Trylon Titan Tower at 64 feet (with a 3 element Steppir)
and it's 30 metres from my home. I intend on burying the feedlines (X2 1/2" heliax and x2 RG213 coax) plus rotators cable and Steppir cable. I was going to dig a 4" wide by 6" deep trench then just bury them. Yeah, that's alot of work with a shovel. Any better suggestions? This is my Labour Day weekend job (get the pun?). 73 de Mike VE6HMG |
Burying Coax Feedlines & Control Cables
On Sep 5, 10:20*pm, "Mike, who else?" wrote:
I have a 64 foot Trylon Titan Tower at 64 feet (with a 3 element Steppir) and it's 30 metres from my home. I intend on burying the feedlines (X2 1/2" heliax and x2 RG213 coax) plus rotators cable and Steppir cable. I was going to dig a 4" wide by 6" deep trench then just bury them. Yeah, that's alot of work with a shovel. Any better suggestions? This is my Labour Day weekend job (get the pun?). 73 de Mike VE6HMG That is my setup but I put large 4 inch plastic tubing in the trench so that the innards could be easily removed, inspected and added to without having to re dig the trench each time. I left a heavy wire in place to make it easy to make changes over the years. Because of the length underground and then the tower I used 7/8 heliax. I also placed a pipe into the tower concrete so I could place the coax inside the tower if I wanted without the possibility of the mower hitting it. |
Burying Coax Feedlines & Control Cables
Mike, who else? wrote:
I have a 64 foot Trylon Titan Tower at 64 feet (with a 3 element Steppir) and it's 30 metres from my home. I intend on burying the feedlines (X2 1/2" heliax and x2 RG213 coax) plus rotators cable and Steppir cable. I was going to dig a 4" wide by 6" deep trench then just bury them. Yeah, that's alot of work with a shovel. Any better suggestions? This is my Labour Day weekend job (get the pun?). 73 de Mike VE6HMG Well, if it were me and more than a few feet, I'd rent a trencher for installing sprinklers systems and put it all in a PVC pipe with downward facing elbows at each end stuffed with foam to keep bugs and water out. Mine has been out there for about 6 years and no water or bugs yet... -- Jim Pennino Remove .spam.sux to reply. |
Burying Coax Feedlines & Control Cables
On Sat, 5 Sep 2009 21:13:57 -0700 (PDT), Art Unwin
wrote: On Sep 5, 10:20*pm, "Mike, who else?" wrote: I have a 64 foot Trylon Titan Tower at 64 feet (with a 3 element Steppir) and it's 30 metres from my home. I intend on burying the feedlines (X2 1/2" heliax and x2 RG213 coax) plus rotators cable and Steppir cable. I was going to dig a 4" wide by 6" deep trench then just bury them. Yeah, that's alot of work with a shovel. Any better suggestions? This is my Labour Day weekend job (get the pun?). 73 de Mike VE6HMG That is my setup but I put large 4 inch plastic tubing in the trench so that the innards could be easily removed, inspected and added to without having to re dig the trench each time. I left a heavy wire in place to make it easy to make changes over the years. Because of the length underground and then the tower I used 7/8 heliax. I also placed a pipe into the tower concrete so I could place the coax inside the tower if I wanted without the possibility of the mower hitting it. I just hate to admit that Art is right (this time only). Conduit is the way to go. Don't direct bury the cables. Bury conduit and pull the cables through. Incidentally, a local state radio building went cheap and used direct burial cables. 3 months later, the whole mess failed. I popped the pull box cover and discovered that the gophers had chewed through the coax and control cables. I don't know what manner of ground you're working with, but you might consider horizontal drilling. See: http://www.borit.com About $250 or available from your local rental yard. Most plumbers and electricians have one or something like it for laying conduit under driveways and sidewalks. The standard back reamer is about 5" diameter, which is about right for 4" I.D. schedule 40. Otherwise, you get to do some trenching. Sweat or Ditch Witch from the rental yard. You decide. You'll need to go considerably deeper than 6 inches. Check your local electrical code, but as I vaguely recall, it's at least 2.5 ft. Putting 1.8" of dirt on top of a 4.2" diameter pipe just isn't going to work. The first time someone drive a vehicle over the conduit, it's going to crack. Dig deeper. Actually, I'm not sure that 4" diameter will work. Measure or calculate the required diameter. Just use a circle template and draw the bundle on a piece of paper. Leave PLENTY of extra room. Be prepared to leave extra space to pull the RF connectors through (one at a time) or you'll be cutting off some expensive Heliax connectors. Don't forget to leave a polypropylene pull line in the conduit for repairs and additions. You'll need 100 meters of line as you need to pull a new line through with every wire pull. 30 meters is a long way for a conduit pull. You may need to get some slimy cable lube to make it easier. You can try to pull the whole bundle through at once, but I don't think you'll make it, especially with 90 degree elbows at each end. Put some effort into making sure that the conduit is waterproof. This is best done by proper gluing and testing with an air compressor and bubble soap mix. I'm partial to sealing the ends and pressurizing the conduit, but that's overkill for the typical ham installation. You'll need a 90 degree elbow at each end. Use the largest radius you can get away with. Heliax does not like to be snaked around sharp corners. You'll also need some kind of protective cover or rams-head at the conduit ends. You don't want the open end of the conduit pointing up and acting as a funnel. You should also get some useful pointers from the Tower Talk mailing list: http://www.contesting.com/FAQ/towertalk In case you haven't noticed, this is a bit more than a weekend project. It's also not cheap. Good luck. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Burying Coax Feedlines & Control Cables
"Jeff Liebermann" wrote in message ... Conduit is the way to go. Don't direct bury the cables. Bury conduit and pull the cables through. Oh, yes -- please. I did my satellite dish that way in 1985 and have had no problems. You'll need a 90 degree elbow at each end. Use the largest radius you can get away with. To the OP: A sweep elbow is that "large radius" section. Sweep elbows are available in various large radii, like 36", and will treat your Heliax or other cable bends kindly. The plumbing trades use them, too. This picture shows a half-buried sweep elbow http://sugarmtnfarm.com/blog/uploade...GElectPedestal OpenT6799w.jpg It's from http://sugarmtnfarm.com/blog/2009/08...-electric.html The article may provide the OP some tips. RELATED: With my dish install, I picked too-small PVC and couldn't pull the whole length. I had to cut the PVC into sections, pull the conduit through each section (and through new couplings) and then glue the sections back together. My mistake wasted half a day. Check your "pull-ability" before gluing your parts into a unit. Sal |
Burying Coax Feedlines & Control Cables
On Sun, 6 Sep 2009 22:33:52 -0700, "Sal M. Onella"
wrote: To the OP: A sweep elbow is that "large radius" section. Sweep elbows are available in various large radii, like 36", and will treat your Heliax or other cable bends kindly. The plumbing trades use them, too. I've often thought I would try a 45 degree elbow, and then a straight section of pipe coming out of the ground at an angle. That makes it much easier to pull but does look a bit odd. It also has the advantage that I might be able to use some manner of power assist to pull the cables through the conduit. Pulling on a 90 degree elbow is a sure way of breaking it. 45 degrees can be handled with a pully or careful positioning of the winch. Disclaimer: I've never done this so beware of surprises. RELATED: With my dish install, I picked too-small PVC and couldn't pull the whole length. I had to cut the PVC into sections, pull the conduit through each section (and through new couplings) and then glue the sections back together. My mistake wasted half a day. Check your "pull-ability" before gluing your parts into a unit. One tower owner had a 90 degree elbow projecting out of the ground near the outside of the concrete tower pad. He tried to pull the entire cable bundle through at one time with a winch hooked to a pully on the tower from above. Instead, he pulled the 90 degree elbow and about 10ft of pipe out of the ground. I didn't see it happen but was involved in the subsequent cleanup job. Moral: Don't let the cable bundle get twisted as it enters the conduit or it will develop a "lump" and jam. Tower drivel: http://www.agl-mag.com It's totally for commerical tower owners, doesn't have anything on construction, is stuffed with tower politics, but does make interesting reading. Full issues are downloadable. http://www.qmags.com/magazines/PubHomePage.asp?publication=89 -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Burying Coax Feedlines & Control Cables
Thank you all for your responses. I definitely need to review the best
approach. I've gone through a lot to put this tower up and don't need to have a weak link in the system. I'll look into getting conduit that meets electrical code for Alberta. As far a critters are concerned, I have field & deer mice along with voles so to keep this little buggers out, this is the best way to tackle the job. I do have an electrician coming to my home for other upgrades and just may have him work on the conduit piping, too. Time is against me as I have approximately 6 weeks before the ground freezes. Oh yes, I have about 2 feet of beautiful Alberta topsoil before I hit clay. I'll keep the newsgroup up to date with my progress. Once again, I thank everyone for their ideas. 73 de Mike VE6HMG |
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