I just finished digging 4 anchor holes 16 in in dia and 5.5 ft deep and the
tower foundation hole 30 inches in dia and 4.5 foot deep for a Rohn 45
Foldover tower. It is the 64 foot version. The holes were all dug in
"solid rock". Took 5 hours to dig the holes with a 32,000# pier truck. I
didn't like Rohn's recommendations to put the four anchor holes on a 25
foot radius (obviously designed to keep the antennas out of the guy wires
when folded over), but I followed their design anyway after calculating the
guy wire and base reaction loads, and they were higher than normal, but
reasonable. I also dug a 9 inch hole 9 ft deep for a ground rod and never
did get through the rock layer. Wonder how the ground will work?
Now, I am getting cold feet about ordering the tower, after looking at Glen
Martins Hazer that runs on a bolt on aluminum track on the Rohn 45 tower.
I got one response from the local dx packet cluster that highly recommended
the Foldover tower over the Hazer.
Question 1: Does anyone out there have any recent experience with the 64
foot Rohn 45 Foldover (rated 130#) or the Glen Martin VH8-70 Hazer (rated
225#)? I can't afford to buy the wrong one since this is a one time
investment for me. I am getting to the point where I do not want to
continue to climb towers everytime something quits working!!!
I have always used fixed towers, but this qth is located on a hilltop
approximately 400 foot above Fort Worth and has a sloping terrain to the
horizon in all directions. If you believe computer programs, the 64 foot
will work ok with this type of location.
Question 2: Does anyone have a good lightning protection recommendation
for a tower that I can implement on this one? I am very concerned with
lightning and grounding since this tower will be the highest thing for
several miles in all directions and Texas is second only to Louisianna in
average lightning strikes. I was planning to tie all anchors to the tower
with #6 copper wire, but have no idea if this is adequate. Driving ground
rods is out of the question, although, I do have the one 9 foot hole and
will use each of the anchor holes as grounds, also. The power service is
200 amp and comes in 150 foot underground on the North side of the house to
the power panel in the ham shack. The tower feed lines (3 - RG213)and
rotor and control cables will come in through the attic on the West end of
the house. If anyone has solved this successfully before, I would
appreciate any information you could forward to me. I would like to have
the polyphaser book on grounding, but I have not decided whether it is
worthwhile to purchase at this time, but I have read the polyphaser catalog
and notes. None of them have very good specifics on what to do for
lightning protection.
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