What next , hambrecht ? Are we going to discuss rhombics ? and what would
that have to do with the average scanner user, that uses a 1/4 or 1/2 wave
vertical for an antenna ? ABSOLUTELY NOTHING. So far, we have heard from
people about their "hf wire antennas", we have heard from you about
"plumbers delight" beams (which , by the way still need a matching system )
, and we have now heard this "the antenna is directly grounded" nonsense
from you, all over again. Long wires ? I was probably running one when you
were still in diapers....
By the way, i never said the shield on the coax "contributes to the noise".
that is not what i said. I said, for all practical purposes, that if you
dont ground the damned coax shield, then it electrically does NOT EXIST.
Sure you have a ground on it in most cases , if it is hooked to the rig. the
rig either has a three wire cord that provides a ground (not to mention the
white lead in the ac cable, that is hooked to the same place), but you
should have grounded the rig's chassis to ground yourself anyway, to shorten
the ground path ! (you DID ground the rig, didnt you ?) What was that you
say ? the rig runs off a 12-volt power supply, and there are only two leads
to the rig, plus and minus ? then you better go out there and drive a ground
rod ! because the CHASSIS Of THE RIG IS NOT GROUNDED ! (and neither is the
shield on the coax ! ) It's an epiphany. Oops sorry about those 10-dollar
words ! I got that bad habit by actually studying to GET MY LICENSE. No dick
bash books around here..... quite a few Bill Orr, ARRL, Bill Cheek, etc...
but no bash.. hmmm.

"Zombie Wolf" wrote in message
...
byt he way, what do you think this "counterpoise" IS ?

As far as common mode noise, i was not referring to common mode noise. I
was
referring to noise that penetrates the un-grounded shield , which is about
as effective as a shield when not grounded as wet toilet paper. All this
info was well known and written about 50 years ago . Where have you been ?
Now, the fact is, when you ground the antenna pipe , on a 1/4 or 1/2 wave
vetical antenna , you usually ground the shield of the coax also , since
the
GROUND radials on these antennas are designed to be hooked up to GROUND.
They therefore are usually made so that these ground radials have a
connection directly to the anntenna mount where is clamps to the pipe, in
order to facilitate this grounding. I cant believe i have to keep
explaining
this stuff , that any NOVICE had to know a few years back, to you people.
Your wonderful "j-pole" does NOT operate at ground, since it is a stub
tuned
antenna, and this is what provides the isolation for the active element,
jesus , get a book and read it once in a while , will you, instead of
spending all your time on here talking sheer idiocy ?

"Dr. Fred Hambrecht Sr" wrote in message
...
May I take exception with your statement? Many antennas are operated at
DC
ground. A J-pole, and any beam that is of "plumbers delight"
construction
come to mind as I type.

As far as the shield contributing to noise, pure nonsense. If the shield
and
the center conductor are connected to the radio it has an RF ground from
the
antennas counterpoise. In the case of a long wire, a ground is necessary
to
provide a counterpoise. A ground rod does a very poor job of providing
one.
The main reason for a ground rod is lighting protection, and static a
bleed
off path.

No grounding system in the world will remove common mode noise.



"Zombie Wolf" wrote in message
...
No antenna is at DC ground, if it is going to function as an antenna.
As
far
as static building up on the outer braid of coax, if you have your
antenna
firmly mounted to the pipe metal to metal, then grounding the pipe at
the
bottom is as close to "grounded" as you are going to get, and this
will
ground any "ground" radials that are not active elements of the
antenna,
and
usually put the shield of the coax at ground, also. There is a more
important reason to ground the antenna pipe, and thereby the shield of
the
coax. It keeps local electrical noise and interference from
penetrating
into
the coax , and raising the noise and interference in the reciever. The
signals you are trying to pick up on the scanner or radio are hundreds
of
times weaker than a lot of local noise is, and the noise will tend to
over-ride the signal if this is not attended to. (the coax actually
acts
like an antenna when the shield is not at ground).
This will tend to severely limit your hearing range on the radio ,
especially in locations that are rife with electrical noise , like in
the
city, near a factory, etc, etc, etc
"Bob Parnass" wrote in message
news On Wed, 20 Aug 2003 22:37:52 -0700, Jason Wagner wrote:

... On the other hand, I do like the idea of having static build
up
on coax bled to ground. But does this product really work?
Anyone
using
them?

If you want to avoid building up a static charge
on your antenna, use an antenna that is at "DC ground."
Discones and Ventennas are not at DC ground.

I have a few of the spark gap arrestors like those
you cited. It takes a high voltage to jump the air gap
inside them. Using a more sophisticated receiver protector
with a gas cartridge will discharge the voltage to ground
at a lower voltage level than an air gap and provide more
protection.

I use an older Alpha Delta Transi Trap on my shortwave receiver.
It contains a replaceable gas plug. A newer version is
show at http://www.alphadeltacom.com/tt3g50.html

Disconnect your scanner from the antenna when not in use,
especially during lightning season.

--


================================================== =======================
Bob Parnass, AJ9S GNU/Linux User
http://parnass.com