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KG6BAJ > NWSGRP 08.09.09 03:49l 110 Lines 4982 Bytes #999 (0) @ WW
BID : 10904_N1OES
Read: GUEST
Subj: Re: Burying Coax Feedlines & Control Cables
Path: DB0FHN<DB0FOR<DB0SIF<HB9EAS<OK0NHD<DB0ERF<OK0NAG<IK6ZDE<IK2XDE<F8KFY<
F4DUR<CX2SA<N6RME<KG6BAJ<KG6BAJ
Sent: 090906/2001Z @:KG6BAJ.#NCA.CA.USA.NOAM #:10904 [Grass Valley] InterGate $
** NEWSGROUP: rec.radio.amateur.antenna
** FROM : "J. Mc Laughlin" <jcm@power-net.net>
Dear Mike: If you decide not to place wire in conduit, consider the use of
PE jackets. Heliax seems to have PE jackets. The animals in Michigan love
chewing on PVC jacked wire/coax. You might be far enough north not to have
the sort of chewing animals common in Michigan.
My experience with 4 inch conduit (plastic, outdoor) is that one may pull
one set of wire/coax while assembling and sealing ten foot sections, and
then forget about pulling more wires.
Let us all know what you ended up doing. 73, Mac N8TT
--
J. McLaughlin; Michigan, USA
Home: JCM@power-net.net
"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:8eg6a51rhp9la27dkh0nh3ut2mlbkpbqb6@4ax.com...
>
>>On Sep 5, 10:20 pm, "Mike, who else?" <h...@there.com> 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 jeffl@cruzio.com
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558
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