On 10/03/2005 4:15 PM, clvrmnky wrote:
On 10/03/2005 1:04 PM, Cecil Moore wrote:

clvrmnky wrote:

The lack of good RF ground is going to be a challenge, and may
preclude any of this.



If you use a balanced antenna system, you don't need
an RF ground for the receive function.


Hmmm. I can probably make a decent-sized folded dipole out on the
patio. It will have to turn a corner, but I can probably get a
fair-sized loop out there.

Ok, further to this. Even if I'm not to care about impedance matching
or choking, my receiver has an unbalanced antenna input. One side of
the antenna connection simply goes to "chassis" ground.

This implies that I should use a traditional BalUn to make the balance
connection work for me. Otherwise, one side of a dipole or looped
longwire is just going to go straight to ground (such as it is.)

I built myself a reasonably stealthy random-wire running along the top
of my wooden balcony railing (which turns a 90-deg corner around the
building) for a total length of around 25-30 ft. I was considering
simply looping the wire to make a bent, untuned, "folded dipole" (the
wires would be 5-6 inches apart) just to get more wire into the wind.

To realize this, I am supposing I'll have to use a true BalUn to get the
signal into my unbalanced front-end somehow. Since most designs for a
true BalUn assumes I have a decent ground, I'm a bit stumped by your
comment. Perhaps the ground of the BalUn can just go to the coax sleeve?

Thanks for all your suggestions.

On Mon, 14 Mar 2005 13:02:20 -0500, clvrmnky
wrote:
This implies that I should use a traditional BalUn to make the balance
connection work for me. Otherwise, one side of a dipole or looped
longwire is just going to go straight to ground (such as it is.)

Hi OM,

You reject the BalUn (matching/choking) to only presume the
implication (one wire goes to ground) forces you to use it for another
reason?

Wrong implication, even if the solution works. The one side of any
dipole/loop antenna design going "straight to ground" (ground a
euphemism for Hell?) is not a loss in any sense of the design. The
receiver is sharing the same path - unless it is strictly battery
operated without a charger connection.

Your radio wants to see a signal potential applied across its input
and chassis (as you put it, which is suitable enough). With a
monopole the input is satisfied, but you need either a ground or
counterpoise connected to the chassis. With a dipole or loop, the two
returning wires meet the radio's needs at the input/chassis
connection. A ground connection or counterpoise for the dipole/loop
would be benign in the practical sense. You won't need it (unless you
have lightning phobias); and with the common specie of radio you will
have it, somewhere, anyway (it will then simply be uncontrolled and
variable).

Perhaps the ground of the BalUn can just go to the coax sleeve?

That will work fine.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote

A ground connection or counterpoise for the dipole/loop
would be benign in the practical sense. You won't need it (unless you
have lightning phobias);

Well said. And most of us who get anywhere near as much rain as Richard
does (in WA) unfortunately have a LOT more lightning to deal with in the
summer. In that case, shield-grounding the coax of a dipole should happen as
soon as the feedline is down at ground-level, and again at the station
entrance/single point ground, where it should connect to a coax
surge/lightning arrestor.

Perhaps the ground of the BalUn can just go to the coax sleeve?

That will work fine.

73's
Richard Clark, KB7QHC

Indeed, matching transformers such as Industrial Communications Engineers
make, insist the metal xfmr case be grounded for safe and proper operation.
I ground long wires on both an I.C.E. xfmr and a current-type Balun,
directly to ground rods that the equipment is mounted on. This is also the
connection point for ground radials for the long wire, if used.

Best regards,

Jack Painter
Virginia Beach, Virginia

On Mon, 14 Mar 2005 16:53:57 -0500, "Jack Painter"
wrote:
And most of us who get anywhere near as much rain as Richard
does (in WA) unfortunately have a LOT more lightning to deal with in the
summer.

Hi Jack,

In all actuality, Seattle sees the least lightning nationwide. If
you drew a line from Seattle to Miami, you would find that the
incidence of lightning grows roughly ten-fold as you progressed along
that line.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote
"Jack Painter"
wrote:
And most of us who get anywhere near as much rain as Richard
does (in WA) unfortunately have a LOT more lightning to deal with in the
summer.

Hi Jack,

In all actuality, Seattle sees the least lightning nationwide. If
you drew a line from Seattle to Miami, you would find that the
incidence of lightning grows roughly ten-fold as you progressed along
that line.

73's
Richard Clark, KB7QHC

Hi Richard, I knew that, and meant by inference that it was admirable for
someone (you) with so little lightning, to realize it is not a minor-thing
for others.

I might act like my station is bulletproof (because I spent the time and
money to try to make it so), but when you watch that line of a storm
approaching, and lightning is striking every few seconds on a path you can
see coming straight for you, the realization that one is likely to land on
top of you is real, not a phobia, lol. All too often, it does strike one of
the tall pines in my yard, sometimes jumping to non-conductive things like
wooden fences, which it splits on its way to ground.

In Virginia Beach, we get more than half the lightning Miami gets, but
slightly less than half what the 100+ area of West-Central Florida does. It
serves to make summer a lot less fun for those with masts, wires and towers
up in the air!

Best regards,

Jack