Gary Schafer wrote in message . ..
On Fri, 19 Nov 2004 07:44:50 -0500, "Floyd Sense"


As Jack mentioned grounding the cable "at the bottom of the tower like
is used nation wide in tower designs" is ideal. But unfortunately that
is not how it usually gets done. Often the lines come off the tower at
6 to 10 feet above the ground to go to the building in a cable tray.
But it would indeed be best if they were taken all the way to ground
level before exiting the tower.

The reason being that during a strike the tower and associated lines
on it develop considerable voltage drop due to the high current being
conducted. Coming off the tower above ground is like taping a resistor
part way up from the ground end. Allowing more voltage to exit on the
lines rather than the potential at the base of the tower where it is
closer to ground. The tower usually has considerable inductance for
voltage to develop across.

I'm one of those who pulls the coax off the tower at around eight feet
and hangs it on a carrier wire from the tower to the outside wall near
the shack. In the past I've had end insulators at both ends of the
carrier wire. Your point about grounding the coax at the base of the
tower is well taken but is obviously not possible in these situations.
It occurs to me that the same effect can be accomplished by connecting
a #6 or #8 solid wire between the the coax shields where they bend
away from the tower and the base of the tower. Yes?

Taking it a bit further it also occurs to me that the carrier wire
could be connected to the base of the tower at the point where the
tower connects to the ground rods there, then up the tower and
connected to both the coax shields at the eight foot level and the
tower again. Then horizontally to the house wall with the coax, then
down to the ground rods just outside the shack to which the equipment
is also grounded. I'd also connect the coax shields to the carrier
wire again at the point where they turn away from the wire and go
through the wall. One hefty continuous, unbroken length of copper
wire. There would still be voltage differentials involved because
there is no escape from the inductances BUT . . . is my thinking in
the right direction here?


73
Gary K4FMX

w3rv