Jim and Steve, Thank you gentlemen. One gets all kinds of advice and much
misinformation from the community at large but this forum seems a cut above.
I appreciate getting reasonable answers to my questions. It is very handy
to be able to take advantage of the experience base represented here. All
too often I have had to try to work out suitable solutions from first
principles when a small dose of experience would advance my state of the art
by a great margin.
This is my first ever actual tower for a rotatable antenna. It was designed
as a tilt-over crank-up with 2 each 20 ft sections. A friend bought it used
intending to put in a CB station until he took a good listen to CB and just
abandoned the project leaving the tower on skids in his field for over 20
years until he noted my renewed interest in low band hamming and gifted it
to me. I have cleaned and painted it, replaced the bearing in the sheave
that reverses the cable direction and made some mods. I removed the old
hand winch and its mounting plate and welded a length of 2x8 inch channel
in its place. To this I have mounted a small electric winch (smallest
readily available was rated 1500 lbs.) I welded half of a DIY piano hinge 7
ft above the base. The other half of the piano hinge is 15 ft AGL atop a 4
inch diameter steel pipe with 1/2 inch wall thickness set into 26 each 60 lb
bags of redi-crete. I built a galvanized weather enclosure for the winch
with a hole for the cable. Rubber "lips" are mounted to mostly seal the
exit hole from water ingress while not fouling the level wind action. (Think
lips sucking in a strand of spaghetti.) I really do aspire to be able to
remotely telescope this tower up and down unattended remotely from the
shack. Limit switches can't be that hard to construct/install.
A just under 7 ft extension to the bottom of the lower mast section gives
extra leverage for manually raising and lowering the tower (tilting not
telescoping) and at just under 7 feet it just clears the top of the concrete
in which the 1/2 inch wall pipe is set. After a rotator and short mast to
mount the K4KIO hex beam the base of the antenna mount will be about 52 ft
AGL. I am guying the bottom 20 ft tower section that is 28 ft AGL due to
the boost from the 4 inch pipe. When tilted up fully a pin is dropped into
rings, one on the pipe and the other on the tower, to pin the tower to the
pipe in the vertical position. It is my intention to not leave the tower in
the raised telescope up full height position except when operating with that
antenna in less than high wind conditions.
It has been raining just a little every couple days, enough to keep me from
mating the tower to the vertical pipe as I don't want the tractor to be
slipping and sliding on the slope while my assistant is up a ladder trying
to put in the hinge pin. I have a 3 ft deep 6 inch wide trench running 100
ft from my Hy-gain Hy-Tower 7 band (soon to be 8) vertical on the roof ridge
of a metal barn north out into a field where the tower is going. It is
raining now but Fri, Sat, and Sun are predicted for 0% chance of rain and a
ham friend is driving up fro Baja Oklahoma (AKA Texas.) We will be burying
2 each 4 inch diameter PVC conduits in the trench. One for coax and one for
power and control lines. and room to grow. Yet another first for me is
putting connectors on Andrew hard line but luckily my friend has over 30
years experience doing it.
My current plan is to make a hole in the conduit at the low point (the run
is on a definite unidirectional slope ) where I will have excavated extra
dirt and put in geotextile cloth wrapped around a cubic foot or so of pea
gravel. This should handle any condensation. I will mix in a good dose of
sodium bentonite into the fill dirt above and in the vicinity of the weep
hole. Bentonite is a typical ingredient of kitty litter, some floor sweeping
compounds, oil absorbers for shop floors, and is the chief ingredient of oil
well drilling mud. It is also used for sealing leaks in ponds. It will
reduce the penetration of surface water down to the pea gravel, reserving
the gravel's interstitial spaces for drained condensation.
Well, guys, there it is... THE PLAN I invite any criticisms that
don't suggest backing up and redoing. Much of the work listed will happen
Fri and Sat. After that it will be academic and overtaken by events (OBE.)
The above room to grow comment regarding the two 4 inch conduits is because
the trench extends another 282 feet north with another "node" at the 141 ft
point from the described tower install and the final node at the 282 ft
point at the trench's terminus. These two additional "nodes" will get
towers subsequent to the above install. The conduit will be glued up and
buried with pull ropes in place all the way along the trench as I need to
backfill prior to allowing my black Angus herd back into this pasture within
a few weeks.
I???d be happy to make any clarifications if any of my descriptions are too
obscure. I tried to eschew obfuscation. Honest.
Patrick AF5CK
-----Original Message-----
From: K7LXC@aol.com
Sent: Tuesday, October 29, 2013 11:25 AM
To: towertalk@contesting.com ; patrick_g@windstream.net
Subject: Re: [TowerTalk] Tower and antenna decisions
Anyone care to advise me regarding issues relating to the coax run up
the
tower in the case of a crank-up tilt over with a rotating antenna atop it?
1. How do you keep the coax tangle and jam free when the rotator
rotates?
Howdy --
There are 2 ways to do it: 1) tape all the cables coming down the mast
together and leave 4-5 feet or so between where it leaves the mast (or
antenna or whatever) and where it attaches to the leg, or in a crank-up
case,
to the coax standoff.
2) is where you coil 2-3 turns of coax around the bottom of the mast
before attaching it to the leg/standoff. You need a flat plate on the top
and enough room for the coax loops.
2. What are the best choices for the part of the coax next to the
rotator?
Should all the moving coax be some kind of "ultra flexible cable."
As long as you use a coax with stranded center conductor, most
coaxes will work.
3. How do you keep the coax from getting "messed up? when raising and
lowering the crank up? I have heard there is a way to keep the coax inside
the tower tangle free. Is that so?
NO. Sooner or later the cables will get chopped and I'm having
trouble picturing how you'd actually do it.
Again there are 2 ways to do it. 1) Secure the cables to the
standoffs. This is time consuming since you have to run the tower up and
down
repeatedly in order to get everything spaced right. 2) My preference is to
tape
all of the downward cables together at about one foot spacing and while
it's secured to the top cable standoff. In this case the cables will rise
and
fall together and pass thru the standoffs. When lowering it, the cables
will just lay on the ground as it comes down.
This is my first time so please treat me gently. I have never had a
rotating
ham antenna before.
Woo woo - fun ahoy!
Cheers,
Steve K7LXC
TOWER TECH
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________
No infections found in this incoming message
Scanned by iolo System Shield
http://www.iolo.com
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|