[TowerTalk] Re: Lightning & parasitic elements arcing

[Jim McDonald]

I forgot to add one thing.  A lightning bolt did strike the desert ground
about 200' from the tower last year.  Strong enough to destroy a neighbor's
pool pump probably 300' away.

Jim N7US

----- Original Message ----- 
From: "Jim McDonald" <n7us at earthlink.net>
To: <towertalk at contesting.com>
Sent: Monday, June 02, 2003 6:37 AM
Subject: Lightning & parasitic elements arcing


I have a Force-12 340 (3L 40) at 101' and a C-31XR below it on the same mast
at 90'.  On top of the mast, at 105') is a Diamond F-22 2M
fiberglass-covered antenna.

When I lived in New Mexico, I had a Mosley TW-33XL (WARC version of a
TA-33), which has grounded parasitic elements, above the 40, and the
tribander then was a KLM KT-34XA.  I had no arcing from the 40M parasitic
elements to the boom during storms, though I do now.  N6BT told me that was
because the top antenna shielded/protected the 40M yagi, which has floating
parasitics.  (The 89' tower was at only 49' due to local zoning.)

I have Scotch electrical tape between the boom and the centers of the
elements of the 40M antenna but I get lots of arcing/popping during storms.

The choices:

1. Ignore it - it's a good static drain.

2. Rent a boom truck and ground the centers of the parasitic elements on the
40M yagi.

I have seen four direct hits during a 30-minute period in one storm here in
Arizona, and probably others have occurred too.  No apparent damage.  Have
several 8' rods at the base and in a coax/control line trench to the shack,
ICE protectors on the coax cables, rotor line, and DX Engineering switch
cables, and the ground rods connected to a large horse arena pipe fence near
the tower.  Use mostly Cadwelds to connect wire to rods.

Jim N7US