[TowerTalk] Length of Mast

[Bill Tippett]

W0UN wrote:
 >K0RF, W4ZV, and myself all noted that electrical storms would stop
striking as they approached the grounded towers (with lots of elements)
and then resume striking as the cell passed by the towers.  Typical
experience indicated that the lightning would stop some 1/8 to 1/4
mile away and resume in an equivalent distance once the cell had passed.

         Just to add to John's comment, my wife and I were
having dinner one evening during some stormy weather.
We were amazed to see a lightning bolt strike the bare
ground only about 500 feet from my 155' tower.  That tower
was the tallest thing for miles around yet lightning chose
to strike an in an open field.

         Many times I could hear arcing across my RG-17 coax
that fed that tower.  I'm not sure but I seem to recall the
breakdown voltage of RG-17 is around 11 kV.  It was not
unusual to even hear arcing in relatively clear weather
when a dark cloud might move overhead from the front range
of the Rockies just miles to the west.  In the 13 years
I had antennas up in that location, I was never hit by
lightning that I know of.  I agree with John that the
antennas apparently bled off the charge (source of the
arcing in my coax) and averted direct lightning hits.

         Here in NC, that same tower has been hit many times.
I only use it for a 160 vertical here and have not put
up the KLM520 and KLM340 that I had up in Colorado (all
KLM parasitic elements were grounded).

                                         73,  Bill W4ZV