[BC] AM transmitter lightning sensitivity issue

[Gordon Carter]

And I always thought the ones on top of light posts and such were to
keep the birds from perching...

Gordon S. Carter, CPBE, CBNT
Chief Engineer
WFMT and The Radio Network
5400 North St. Louis Ave.
Chicago, IL 60625
773 279-2071

-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net] On Behalf Of Paul Smith W4KNX
Sent: Thursday, May 22, 2008 9:29 AM
To: Broadcasters' Mailing List
Subject: RE: [BC] AM transmitter lightning sensitivity issue

Here in this area, these dissapation devices are all over.  Almost all
traffic signals now have them, hospitals have them along roof lines.
Several manufacturing plants and electric substations have them.  Those
that
have them all note a much lower incidence of lighting damage and
strikes.
These are not the old style lighting rods, but devices that look like a
wire
brush with hundreds of sharp needles on the ends.  This is the lightning
capital of the US and a great test area.  I also see the use of what
looks
like razor wire you would normally see around a jail wrapped around guy
wires on towers.

Paul Smith,
Sarasota, FL

-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net]On Behalf Of Ron Nott
Sent: Wednesday, May 21, 2008 7:00 PM
To: Broadcasters' Mailing List
Subject: Re: [BC] AM transmitter lightning sensitivity issue


Before a thunderstorm arrives, the electric field builds up to many
thousands of volts per meter from the ground up into the
atmosphere.  If it is not discharged, it can cause VSWR trips (and
eventully lightning) long before the thunderstorm arrives.  There is
nothing wrong with your antenna system and its ground system.  The
transmitter sees a problem and reacts to it properly.

If you discharge part or all of the electric field as it builds up,
you can prevent this from occuring.  Charge dissipation products are
not glorified lightning rods, but dissipate the near electric field
as it builds prior to a storm to greatly reduce the incidence of
lightning and its effects.  The closed minds on this list will tell
you that it does not work because they are incapable of grasping how
it works, but in fact it does work.  A lightning strike is measured
in Coulombs (one ampere for one second).  The reason that lightning
does damage is that it discharges this energy in a matter of
microseconds.  If you discharge it slowly over a time period of
seconds or minutes, the discharge is normally in milliamperes or a
few amperes instead of 10,000 to 30,000 amps or more in a few
microseconds.

There is a solution to your problems, but only if you have an open
mind. Lightning is not magic or evil witchcraft.  It is all based on
science and specifically Ohm's law and the time constant formula (TC
= RC).  If you really want to solve your problem, please contact me
off list.  If you just want to whine, then don't.

Ron Nott


_______________________________________________

The BROADCAST [BC] list is sponsored by SystemsStore - Your Premium
Supplier Of Components To Build and Maintain A Technical Infrastructure
www.SystemsStore.com       Tel: 407-656-3719    Sales at SystemsStore.com