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
--
73 dit dit,
David E. Shelton, RN
W4DES Amateur Op
w4des@bellsouth.net
Amateur Radio Transmitting Society
of Louisville, KY
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|