Hello to the list,
I am new here, but have come for some ideas. I have a 100 foot Rohn 55
recently installed. There is nothing on it as of yet. The tower is
guyed at the 95 foot level with a single set of un broken steel 5/16"
EHS guys, they are insulated to the tower by 3 foot fiberglass strain
relief rods. The second set of guys are 1/4" EHS guys, also insulated
the same way from the tower, these are at the 60 foot level. At the 29
foot level is a set of 3/16" EHS guys, not broken up either but not
insulated from the tower. This set is connected directly the the guy
bracket assembly. There is a reason for this configuration, but I will
not get into it here. I was thinking of trying to use this in some
fashion as a 75 meter vertical. Since the tower is "grounded" by the
lowest set of guys at the 29 foot level, I was thinking of attaching an
elevated set of radials at this level and feeding the tower with power,
maybe through some sort of shunt feed, at some point above the lowest
set of guys. This would leave the remaining 70 feet of tower above the
lowest guy section as a radiator, since this part of the tower is
insulated from the guys.
Has anyone performed a similar type of installation? Or has anyone
modeled this set up on a computer program? I would love to hear from
anyone with a similar design.
The only concerns I have here are the fact that the tower is not
insulated from the ground per se at the base. It is sitting on a
concrete base via the flat base section. The lower set of guys are
grounded to the tower and at the anchors. In fact the upper two sets of
guys are also grounded at the anchors, but just not making electrical
contact at the tower do to the strain relief rods. I was thinking of
installing elevated radials mounted to a Nylon block just above the
lower guy bracket assembly, and then running an elevated feed with a
variable cap up the side of the tower at some point. Would this in
effect make a full length 1/4 wave vertical for 75/80 meters with an
elevated base at the 30 foot level? Or might I be looking at some
problem with the lower 30 feet of tower and guys reacting with the
antenna part of the tower? The tower is one unit, it is not broken by
any insulating sections.
73, Bruce K1XR
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