This my second attempt to post ... if this was received earlier I
beg forgiveness ... So here I go again:
Hi to the group! Dave Hockaday WB4IUY put me on to this group and I
have monitored ideas for the past couple of days . . . very
educational!!!
I have recently erected a 135 foot old (40+ year old) tower in my back
yard. I have not mounted any antennas that have been connected to
radios yet ... and need some help or suggestions.
First of all I'm working on a home page and will add some pictures of
the tower in a few weeks to help everyone understasnd my site. I will
try to have some images scanned in by next week for jpg or gif viewing.
The tower was puschased at State Bid for very little $$$. I followed
Rohn's specs for a three legged tower for my footings. That put four
legs mounted on 4 - 10 foot columns of concrete poured in a 2 foot galv
drain pipe. Each pipe has re-bar running the length of the column and
exiting at the base to form a 4 foot re-enforced pad. The columns rest
on hard clay 8 feet below ground level in 4 x 4 (minimum some closer to
5 x 5 foot) holes. Each column has a least 4 feet of concrete poured at
the base of the columns. Plus the column of concrete. The tower is
mounted on 8 1" by 18" L-shaped bolts that have had a 4 foot angle iron
extension welded to them with off sets. The tower base is 12' x 12' and
a 5' 8 sided alum platform was mounted at the top of the tower. A 14' x
14' concrete pad has been poured at the base to house the 8' x 10.5'
equipment shack. A total, of 28 yards of concrete have gone into the
project. Tower has almost no rust(only on climbing pegs) for its age.
Tower is made of galv angle iron with cross bracing between horizontal
supports which are spaced at ends of each single run of support angle.
Sorry for being so long winded but want to give everyone the best
description before pics are available.
I plan to mount the following on a 20' alum mast (2" with 1/2" thick
side walls) at top that will have 2" bearing mounted ontop of platform
with 8' of mast running thru platform to Tailtwister rotor 8' below on
platform. That leaves 12' above platform where 2 - 440 beams, 2 - 2m
beams, 1 - 6m beam, 1 - 220 beam, and a 2m,220,440 verticle will be
mounted on the mast. I plan to later add ATV and 900 mHz beams. Also I
will mount about 5 additional verticle anetnnas as side mounts. Plans
now are to pull my HF dipole antennas off as well. I plan to run 1 5/8"
and 7/8" hard line for most of the antennas and flexi 4 foam core coax
as jumpers. I have been purchasing Polyphaser arresters as money and
availablity permitted. And they will be mounted in the equipment shack
and to my pending ground system. And hard line run into my ham shack
30' from the tower.
I have several questions/comments:
1) I plan to make to 3 runs of 1 5/8" and 3 to 4 runs of 7/8" hard line
up the tower. There is no hard line ladder and I am looking at building
a ladder out of electrical galv uni-strut to ease the tower loading.
Does anyone have comments or suggestions.
2) I now see that I need to ground all tower legs(presently only 2 legs
with the greatest distance from the house are grounded with 5/8" 10 foot
copper clad rods with No. 2 copper welding cable (insulated/stranded).
I see that the sheilding needs to be removed and wire soldered??? I
mounted heavy brass lugs on tower legs (brass to galv) with brass clamps
on rods. Do I need to put stainless steel spacers between galv tower
and lugs?
3) I plan to,ring my house with ground rods and a ground field on the
opposite side of the tower from the house as Polyphaser recommends (35
grounds are planned) Do I need to Cad weld all connections or what are
suggestions. Also if copper stranded wire (provides greatest electrical
conductive surface area) is used does it needs to be solder tinned. Is
this for prevention of corrosion do I use tin or silver solder??? Will
not tinning reduce the surface area and reduct potention capacity???
Also any suggestions on driving in ground rods (I'm 45 and not as
"strong" as ground is "hard".)
4) My understanding of lightning strikes are that proper grounding
bleeds off charges that build up and reduces potential for ground
potential developing on tower, trees, etc. This potential originally
created an ion bridge that provides the path from the ground, tower,
tree, etc, for eventual atmospheric discharge. Lightning travels down
this bridge so in fact lightning does start from the ground but does
suffer a downward discharge that is more destructive. (Comment Only not
a question)
Thanks for this forum and I will add more later ... any help will be
greatly appreciated. I can also provide you with many Do and Don't in
buying an old tower, getting a crane contracted and SIZING for the job,
what can go wrong (crane getting stuck!!!) and many other tid-bits of
widsom (after the fact!!!)- most of the site prep and work was hand
labor and "jackleg planning".
Thanks ...Steve KD4WIW
=========================================================================Thanks
to Steve K7LXC who saw my 1st bounce (to the wrong address) and replied
with earlier response. 73 Steve KD4WIW
=========================================================================
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