In a message dated 11/28/01 6:56:32 AM Pacific Standard Time,
bob.applegate@ulticom.com writes:
> Since the sections of a crank-up tower aren't meant to have a tight
> fit, how do people get a good ground at the top of the tower?
A 'good ground' is required at the bottom of the tower - the top is not
so important. Maybe the discontinuities of a crank-up do some good by
introducing enough resistance in the tower/antenna/cable system to discourage
a lightning strike in the first place.
Nonetheless the whole tower is connected by the cables anyway. The
sections themselves may or may not present a consistent path to ground since
they do have the large tolerances that you mentioned.
> Do they put penetrox on the legs to increase the quality of the contacts?
This is almost impossible since you don't always know where the contact
points are and even if you did, it's pretty tough to get those spots
adequately lubricated. Anti-oxidants are meant to be under compression at the
joint and that wouldn't happen with a crank-up. The rain would wash it all
off anyway.
> If I have a crank-up tower that's properly grounded at the base, how
> do I guarantee the top section has a good path to ground, at least better
> than the coax and rotor control lines? I'm just worried about lightning
> protection.
A lightning protection system is supposed to keep transients out of your
house so that's where your concern should be. The potentials between the
tower and ground, the Single Point Ground point at the house and ground, as
well as the potential between the Single Point and the tower, should all rise
and fall at the same rate. If they do, then there isn't any arcing which is
the main damage from lightning.
Cheers,
Steve K7LXC
Tower Tech
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