You can take exception all you want, but if you study any antenna design you
will find that it either has grounded elements, and the active element is
not grounded, or it has some kind of reactive isolation of the active
element from ground. the antenna simply cannot function unless one of these
conditions exist. period.

"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

On 2 meters I use a copper J-pole. The entire antenna is soldered pipe and
any point can be measured to ground with an ohm meter and is at DC ground.
The antenna is fed a few inches up from the bottom with the braid going to
one point on the DC ground and the center lead to another point on the DC
ground. The RF impedance is in the area of 50 Ohms.

I have no earthly idea what you are referring to when you use the term
"reactive isolation". Once any reactive element is brought into the
equation, we have left the DC world.

DC ground is included in no antenna equation I am familiar with, but I stand
ready to be proven wrong.

I reply not to be argumentative, but in the furtherance of knowledge.
"Zombie Wolf" wrote in message
...
You can take exception all you want, but if you study any antenna design
you
will find that it either has grounded elements, and the active element is
not grounded, or it has some kind of reactive isolation of the active
element from ground. the antenna simply cannot function unless one of
these
conditions exist. period.

"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