[Elecraft] Open wire feeder protection

[Ken Kopp]

Paul and others,

I didn't mean to imply the use of resistors on open-wire
feeders to drain off charges built up on the antenna.  It
would work, but the resistance would "mess up" the 
tuning of the antenna unless they were of very high
resistance, which would limit their effectiveness.

I have a 2" wide strip of copper flashing that runs across the
wall of my shack just above the table top.  There are 1/4-20
brass bolts with washers and wing-nuts at interals along the
strip.  This strip runs outside under the wall atop the foundation
to several ground rods driven several feet apart.

The 2-inch spaced feed-throughs for the open wire come into
the shack just above the copper strip and there are large 
RF chokes from the thru-bolts to the strip.  This places the
feeders at ground potential and drains off any unwanted
voltage to ground.  The impedence of the RF chokes is
invisible to the RF energy on the feeders.

I'm "serious" about 160M and there are 32 ground rods on the
property. They're all tied together with #8 CU and to the well's
casing.  There are 120 radials under the 80/160 tower, all tied
into the ground system.

I've also used RF chokes from the terminals of my KW
Matchboxes to the ground post just below the terminals.
Needless to say, the 2" CU strap also runs to the bolt.

Older ARRL handbooks depict a method of building a spark-
gap arrangement between the feeder insulators.  Some have
used automobile spark-plugs in this application.

Using a resistor on open-wire feeders wouldn't be ... in my 
opinion ... a satisfactory arrangement.

73! Ken Kopp - K0PP
k0pp at arrl.net
or
k0pp at ixpres.com