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<3548F98A.4780EE04@bellsouth.net> Date: Thu, 30 Apr 1998 18:22:03 -0400
From: "David E. Shelton" X-Mailer: Mozilla 4.04 [en]C-bls40 (Win95; U)
MIME-Version: 1.0 To: "Dr. Robert C. Smithwick" CC: dale and sue , RFI
Reflector Subject: Re: [RFI] Ground Rod Placement
References: Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit Yes, you should do more to be safe. I
would establish a common ground, one ground source. The ground at the
base of the tower would be best. The single ground rod is not enough for
the tower and antennnas you describe. The ground would quickly, about
one millasecond, become saturated and the "left-over" current from the
lightning strike would come into the shack and the rest is history, so
to speak, Hi Hi! If your ground that you spoke of first is inside the
shack then do not use it! It is an open invitation to current from the
lightning strike to come in and toast your equipment, as lightning is
seeking out a route to ground. What you need to do outside the shack at
the base of the tower. Start adding ground rods and connecting the
ground rods together with ground strap or braid, the larger the better,
minimum 1/2". This is the simple way to map out the ground rod
placement, if the ground rods are the commonly found ones, 5/8" X 8ft,
then they need to be 16ft apart to prevent the ground from becoming
saturated in a direct strike. Whatever the length of the ground rod
double it and this is your spacing. I would add at least three more
around the base of your tower. After placing the ground rods and
connecting them together at the base of the tower, establish a ground
window at the entry site of your coax, rotator cable, remote antenna
switches, telephone lines, cable tv, main power utilities, and anything
else you may have coming into house. This is the site where it all comes
together and works no matter what route the lightning strike's current
comes in, off the tower or antennas via feedlines or utilities services.
You can really start spending some money right here at this point. You
can Polyphaser yourself out of a paycheck or two here. So what is
essential? Great question, I would probably take care of the tower and
accessories first; feedlines, rotator controller cable, remote switches,
and anything else coming off the tower. I have been doing a lot of
research since asking my question to the newsgroup recently. The most
important thing I have to add is a ground inside the shack is probably
the most dangerous thing you can do. OK that is my two cents worth, now
the rest of you guys tell me how I did. Dr. Robert C. Smithwick wrote: >
At 9:49 PM 4/29/1998, dale and sue wrote: > >This is in regards to
W4DES' grounding dilemma. First, both K0IL and > >WA1TQG/5 have made
excellent comments that bear careful review. I'll > >also add: don't
drill through the basement floor for a ground rod. > > > > This 'net' is
a great resource! I have been following it wid great interest > and
saving hard copies. > > Let me ask a question of these experts, such as
Dale, author of the above. > And my question is simply this: > > IF I
haven't gone to extraordinary efforts to establish a true ground >
system as the ones Dale and others describe, and IF I have no
identifiable > problems as a result, should I, "just to be safe"
(whatever that means), go > to all that effort? > > I use a simple 8'
copper rod tied to the transmitter with about a 2" copper > strip about
5-6' long. Equipment consists of maximum power amp (Henry 3K), > 55'
tower, base of which is about 20' from rig. Tower is grounded on one >
leg only with single ground strap onto relatively short rod driven into
the > ground adjacent, antennas are 6 element beam for hi bands, 2-el
40M beam, > and 2-3 assorted dipoles. I have no problem so far as I can
detect - no > 'hot' mics or cabinets, no squeals or howls, nothing. No
TVI to speak of in > my own equipment (TVs, hi-fis, satellite TVs, etc.)
No TVI has been > reported in several years (nearest neighbor about 100'
away). Under these > condx, should I do more?? > > And thanx for all the
ideas! > > "Smitty", W6JZU -- 73 dit dit, David E. Shelton, RN W4DES
Amateur Op w4des@bellsouth.net Amateur Radio Transmitting Society of
Louisville, KY
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