This is one of those "what problem are you trying to solve" issues - ac
safety, lightning, or RF management?
Towers should have an ac safety connection between the tower and the
station/house ground. It is permitted by NEC to use coaxial feed line
shields for that. Bonding over the long distances doesn't hurt anything
and if the conductor is buried, acts as another charge dispersing path
in the soil. But long conductors aren't much use at RF due to
inductance (at low frequencies) and impedance (at RF).
The 200' figure was taken from MIL-419A which is the military's cutoff
for requiring bonding of the tower and building perimeter ground, IIRC.
You can find other definitions of "too distant for bonding" but 419A
actually specifies a figure. There are various references here and
there to 60', 100', etc but I was unable to find an authoritative
reference with those figures.
Perhaps one of the more knowledgeable folks here on the reflector can
add something to that. Jim Lux's post helps clarify things.
73, Ward N0AX
On 10/18/2017 5:21 PM, towertalk-request@contesting.com wrote:
A couple of questions:
1) on page 15 of your referenced document you say a distant tower should not be
bonded to house (shack) ground and go on to connect the coax shield.? How is
that not a connection between the two?
2) Where does 200' come from?
Wes? N7WS
On 10/17/2017 7:09 PM, Jim Brown wrote:
On 10/17/2017 11:39 AM, Bob Shohet, KQ2M wrote:
Please share with me what you would do and why.? Thank you.
Why not just buy and study the new ARRL book by Ward Silver, N0AX, which
covers all of this, and to which I contributed?? Or "Up the Tower" by K7LXC,
for which I contributed the chapter on Grounding. Or study the slides for the
talk on Power and Grounding for Ham Radio that I've given at Pacificon and the
Visalia DX Convention?
http://k9yc.com/GroundingAndAudio.pdf
73, Jim K9YC
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