Your crankup installation sounds similar to mine. I have three conduits
running about 250': a 4" for transmission lines, a 2 1/2" for low-power
control cables and a 1" for 220VAC.
I used #10 for the AC, and had an electrician install a subpanel with
surge-protected 110VAC circuit breakers at the tower base.
Before selecting the type of conduit, check the requirements of your local
building code. The code may require schedule 40 electrical conduit (the grey
stuff.) If you install sweeps, you should put expansion joints at each end.
The conduit, sweeps, expansion joints, splices, etc are available from
electrical supply houses.
The rule of thumb is to size the conduit at twice the diameter of the
cables. There's no way you can pull three runs of 7/8" hardline through 4"
conduit. It would be very difficult to pull even two runs of 7/8", though in
theory it can be done. It would take a lot of lubricant and elbow grease
(and maybe a winch.) I agree with the other post that recommended you
direct-bury the three hardline runs (and maybe a 4th for good measure!)
It'll be cheaper and easier than trying to pull it through conduit. That's
how I installed a couple of 225' runs of 1-5/8" hardline to a different
tower, and I'm glad I did it that way.
You may be able to get away with a 2 1/2" or 3" conduit for the control
cables. I have quite a few control cables running through my 2 1/2" conduit,
and it was no problem to pull them. Again, size the conduit to 2x the
diameter of the cable bundle, maybe a little larger if you anticipate adding
more cables in the future.
If the trench is wide enough, I would lay the two conduits and the three or
four hardline runs in parallel on the bottom of the trench. If the trench is
narrow, I would lay the conduits at the bottom of the trench, the lay the
hardline on top of them. That's to avoid the conduit crushing the hardline.
For termination, I used Hoffmann 16"H x 16"W x 8"D metal utility boxes with
built-in grounding panels. They're not cheap, but they're weatherproof and
very rugged. I used large boxes because I have a lot of switches and
lightning suppressors in each box.
Home Depot sells several kinds of cable lube that's made for pulling
electrical cables. I don't know if it's better than plain-old soap. I think
the difference may be in what's left when it dries out. But I don't think
you'll need any lube if you direct bury the hardline.
I'm not aware of a comprehensive Ethernet-based system that can be used for
controlling SteppIRs, rotors and switches. That said, I'm pretty sure that
there are separate systems that could do the job, though it would require
more than one run of Cat5e Ethernet cable:
- The newest SteppIR controllers have a remote control board option that
allows you to control the SteppIR over a Cat5e cable running between the
shack and tower. I'm not sure if the remote board requires AC or DC power,
but since you have AC it shouldn't be a problem. I think this is a good
solution because it avoids a long buried run of expensive SteppIR control
cable. There's also a lightning suppression option available for the remote
board. That's a good idea because the driver chips are expensive. You should
join the SteppIR reflector and ask about owner experiences with these
products.
- Green Heron has a "wireless cable" solution that would allow you to
control your rotor and switches via wireless Ethernet. I believe it would
require you to put a Green Heron rotor controller at the tower. If the tower
is too far away for wireless, then you might have to put a small wireless
router at the tower as well, and connect it to the shack via Cat5e. Here's a
link to the Green Heron brochure:
http://www.greenheronengineering.com/download-files/wireless-cable.pdf
The folks at RemoteRig also have an Ethernet- (and web-) based remote
control solution that may work for some or all of the functions you need.
Take a look at this site:
http://www.remoterig.com/wp/
So, in theory it's possible to control everything with one or two Cat5e (or
Cat6) Ethernet cables (plus one or two for backup!) But it could be fairly
expensive and will require a large waterproof utility box at the tower. It
would also be a fun part of the project, at least for me!
Hope this helps.
73, Dick WC1M
-----Original Message-----
From: john@kk9a.com [mailto:john@kk9a.com]
Sent: Monday, September 12, 2011 7:20 PM
To: TOWERTALK@contesting.com
Subject: Re: [TowerTalk] New Conduits
You can direct bury your Heliax, which makes the project much easier and
less costly. You can use 4" PVC DRAIN pipe for the cable conduit. It has
a thinner wall and a belled end so no fittings are needed. It is
inexpensive and vrey easy to work with.
John KK9A
To: <towertalk@contesting.com>
Subject: [TowerTalk] New Conduits
From: "Steve Jones" <n6sj@earthlink.net>
Date: Mon, 12 Sep 2011 14:14:36 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
I need to install underground conduits to my new HDX-589 crank-up tower.
The distence between my garage wall and the tower foundation is about 125'.
I plan to put in straight conduits with a 90 degree sweep at each end where
they come up out of the ground. I plan 4 #10 copper conductors in a 1" PVC
conduit for 220VAC power to the raising winch. For the coax I'm hoping to
score some local surplus 7/8" LDF5-50 heliax. I have been thinking of using
one 4" conduit for three runs of the 7/8" heliax, and a second 4" conduit
for various control cables (RF switches, rotor cables, SteppIR control,
etc.). So I'd have two 4" conduits and one 1" conduit in the trench.
Those of you who have experience with such installations, please tell me:
1. Are these conduit diameters adequate for my proposed loading? I have
put in 4" PVC water pipe and it's unwieldy stuff to work with, so if I can
get by with smaller conduit pipes I'd prefer to.
2. What is a good source for electrical boxes to terminate these cables
above ground at each end?
3. Is there a better way to control the rotor, switches, SteppIR etc. by
using Ethernet in the conduit and local AC power at the tower?
4. Is there something better than Ivory liquid for a cable lubricant?
5. What have I not mentioned that I need to address?
I appreciate any and all advice!
73,
Steve Jones
N6SJ
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|