For once someone went and did some authoritative research instead of just
speculating.... thanks, Bob. This also indicates surge suppressors are
useful on the rotator control cables.
73, Jerry K3BZ
----- Original Message -----
From: "Robert Chudek - KØRC" <k0rc@citlink.net>
To: <towertalk@contesting.com>
Sent: Thursday, December 14, 2006 4:20 AM
Subject: [TowerTalk] Lightning damage to rotor housings (Was: Which
thrusebearing?)
Okay... you guys theorized ever which way to Sunday about damage to rotors
from a lightning strike. Most everyone on the list has had a rotor or two or
three during their radio career. I'll be blunt, I didn't like your
suggestions and all the jerry-rigging ideas that were being tossed about. So
I went to the experts. The two companies that have been in the business of
rotor sales and service. That would be C.A.T.S. and Norm's. Here's my
information request and the replies I received from them both:
KØRC>>>Hello Dr. Rotor (Craig) ! There is a discussion warming up on the
TowerTalk reflector regarding lightning damage to rotor housings when an
antenna mast is struck and discharged down through the tower to ground. What
kind of damage have you seen to rotor housings, bearings, balls, and races
over the years? I am curious about physical damage more than electronics
being destroyed. Does the bearings and races provide an adequate, low
resistance path for a high current discharge like this? Thanks in advance
for any insight and real-world experiences you can provide. 73 de Bob - KØRC
in MN
CRAIG>>>Hi Bob :
Sounds like most of the discussion is pure conjecture and no one has yet
chimed in from experience.
OK, from 30 years of experience working with rotators : A metal housing
protects the interior parts, as does the framework of the tower structure
surrounding a rotator. Lightning damage to a rotator has been almost unheard
of; with the few cases we have seen suspected of coming from the surge on
the cable itself. In my early days when I was in the TV antenna business, I
saw numerous cases of the rotator wiring arcing over to the legs of the
metal tower and the rotator itself surviving just fine.
Now, I would suspect that a rotator with a streamlined design from top to
bottom would be the least susceptible to a lightning surge; but I haven't
seen enough data to back this theory up.
Oh, and to answer your other question. Never ever have we seen any damage to
bearings or races.
Craig,
C.A.T.S.
KØRC>>>Hello Norm...
There is a discussion warming up on the TowerTalk reflector regarding
lightning damage to rotor housings when an antenna mast is struck and
discharged down through the tower to ground.
NORM>>>What kind of damage have you seen to rotor housings [none], bearings
[none], balls [none], and races [none on any of these that I can attribute
to lightning] over the years? I am curious about physical damage [I don't
see much physical damage, I did have one with a broken off upper mast
support but that was because the whole tower came down in the lightning
storm] more than electronics being destroyed. [Everything I get in has
burned up electronics mostly in the control units with lightning coming down
the rotor cable.] Does the bearings and races provide an adequate, low
resistance path for a high current discharge like this? [maybe if they
suffer severe physical damage, guys just chunk them and I never see them, I
don't know. This is all based on what I recollect from the dozen or two over
the last few years.]
Thanks in advance for any insight and real-world experiences you can
provide.
73 de Bob - KØRC in MN
So there you have it. Create a rube goldberg solution to a non-problem if
you like. I'm not going to waste any time, energy, or money protecting my
rotor housing from lightning. Oh, and I can speak from experience, my tower
has been hit by lightning numerous times and I have never had any damage to
the rotor on the tower.
73 de Bob - K0RC
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