On Sat, 02 Jan 2010 17:20:24 -0600, Lostgallifreyan
wrote:

I haven't a clue about intermod, yet. One thing at a time.

The term Intermod is probably mis-direction if you research it.
Basically, if an nearby AM/FM/TV transmitter (and nearby can be on the
scale of several miles) happens to excite your antenna; then its
developed voltage will overload the frontend (Intermod follows, but
the products are not what I am emphasizing here). This overload can
be many, many kHz, or MHz from the intended and tuned signal; and yet
this frequency remote signal will develop an AGC that drives down gain
on your intended signal.

This characteristic is VERY common for untuned frontends in modern
receivers. It is not often noted for poor antennas (those whips, when
they are used for SW), but when a real antenna is attached *BINGO*
sensitivity goes down the toilet. By providing a tuned input, the
side-signal that would otherwise silently drive AGC is attenuated, and
AGC is developed only by the in-band signals.

Right now I see at
least three contradictions (re ground rods, transformers, and feedlines) with
advice from several people, one of which (the guy who wrote the description
of the antenna and balanced line I mentioned) is part of a group of hams who
is turned to for advice by the others. No guarantee of correctness, perhaps,
but if I keep on being told I'm wrong when my stuff is coming as directly as
I can get it from others with experience, then as far as I'm concerned I'll
do what I think best and get out of the crossfire.

A reasonable posture.

Specifically, many times
I've seen advice that service grounds are not adequate because of common mode
noise and local currents, hence the ground rod you vehemently negate.

I don't negate its use, I say that it is NOT RF ground. If you tie
this ground rod to the service ground, then that wire will probably
act more in your behalf than either "ground." There is a world of
difference between safety grounds (what those rod-thingies are) and RF
grounds (which often don't go into ground at all).

Ground is a long and rich story that has been celebrated in this group
for years. It deserves respect and attention well beyond these few
words.

I can
ground to service ground at near end but if the receiver is on batteries, not
connected to anything except a transformer coupling RF from the antenna, then
the ground only needs to be at the antenna end, according to advice I've seen
in several places.

To your specific arrangement - quite true. However, many who have
claimed to have made every precaution then connect their receiver to
an amplifier, computer, what-you-might-call-it and a new path to
ground winds its way through interesting environments that are RF
rich.

Even if I do ground to a water pipe or other local ground,
all advice I see until now insists on having a ground rod as close to the
antenna as possible, no matter what else I do, yet now you urge against this.

I urge against mixing grounds. Such things arrive by the most benign
and seemingly inconsequential actions.

I will stop asking for advice if all I see is vigorous contradiction between
people who claim knowledge I do not have. Diverting that disagreement to one
with me doesn't alter this, I did not originate the info behind the choices I
am considering. Even if all the various contributors come here and duke it
out between them it appears I'll be none the wiser.

Attention to one detail at a time helps, but a lot of this arrived
through responding to the query for antenna port Z. Those adjuncts
that massage input/output Z also fold in the discussion of ground.

Convention has it that you start a new thread for each side-topic that
drives you into conniptions. Asking about the facts and foibles of
ground would be a good start on a new thread - especially when Art's
wet-dreams descend into discussion of particle duality self
annihilation driving all participation away from antenna design. For
instance "Why are ground rods considered insufficient for RF
application?"

I am content to respond to either discussion.

73's
Richard Clark, KB7QHC