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From: Saad Mahaini[SMTP:Saad.Mahaini@MCI.com]
Sent: Tuesday, August 04, 1998 4:37 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Lightning and static Discharge Issues
Hello Saad:
I have had an AEA IsoPole antenna on top of my 20 foot mast coming out the top
of an 89 foot crank up tower for over 5 years in this (fairly high lightning)
location. Before that it was on the top of a few other tower masts for about
10 additional years at other locations. I have not had a direct lightning hit
in that time, but I have heard from others that have with their IsoPole. In
each instance, the upper element tuning network literally exploded and no other
damage was ever noted thanks to the DC short to ground. Pretty cheap insurance!
The antenna is about 10 feet long including the mast the cones are attached to
and it has the maximum gain attainable for that length of antenna thanks to the
superior patented decoupling cones. The wind load is less than one sq. ft.
73/Mike,N7ML
Hello,
I have a 70 ft crank up with 15 ft mast, in a heavily treed lot. I
have a TH11 and a 40m dipole on top. I like to put up an 2M antenna
on top, to hit the DX packet cluster. It has to be an omni directional
(ie vertical), so it's not affected by turning the HF antennas.
The question is how much risk is there putting up a short 2M 4ft
vertical on top, as far as lightning is concerned. I guess it's not
just the height issue, but the tip of the vertical is much pointier
than just the mast.
Other issue, is static discharge. Even if the lightning is not an
issue, how about possible noise getting into the HF antennas resulting
from the vertical's static discharge just above them.
I guess the static discharge noise could be an issue by itself, and
I also like feedback on it when using a tall HF vertical. I plan to
put up a Hytower (53 ft) vertical in the next week or so, and I wonder
if there will be an issue with static discharge noise.
Would it help to install a brass or copper toilet float ball or similar
on top. If so, does anyone have a source for these.
Questions, questions,...
Tnx es 73s, Saad KB6VIR/5 Dallas
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