[TowerTalk] Tower and antenna decisions

Wed Oct 30 11:29:58 EDT 2013

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 at aol.com
Sent: Tuesday, October 29, 2013 11:25 AM
To: towertalk at contesting.com ; patrick_g at 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
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