On Sat, 02 Jan 2010 13:21:03 -0600, Lostgallifreyan
wrote:

Well, my plan is to use a ground at the antenna end, right
underneath it.

This bodes ill if you do not tie that ground directly to the service
ground. Further, a "ground" as you describe it (incompletely) sounds
suspiciously like a ground rod. This is NOT the same thing as RF
ground - not even close unless you live within several meters of low
tide along a major ocean shore.

I'll get a
good 4' ground rod and rig up an 18' vertical whip as I learned of in details
I posted about earlier.

Suspicions confirmed....

I understand that good reception depends on a good
compromise between selectivity and sensitivity, and no doubt the antenna
'tuner' helps with that, though I'll mainly be concerned with good ground and
local common mode noise rejection.

This does not acknowledge the significance of INTERMOD problems.
Experience may have to teach that (when you make all these
improvements and have poor results for your effort).

My first attempt at the line between
antenna and receiver will be a balanced line with a toroid at each end for
current isolation

This is a very, very curious novelty. You do not describe a
"balanced" system with a ground rod and vertical, so any effort at
"balanced" lines is window dressing only. The reason for placing
"balanced" within quotes is due to the inordinate care and skill
required in obtaining a balanced design. It is more often achieved
with coax. Too often, "balanced line" is approached with the
mysticism of universal relief for whatever ails a listener.

and possibly the suggested Norton preamp on the receiver
input,

I must have missed that posting. Sounds like another elaboration.

but I'll try without it first as I suspect I'll get enough signal
strength to satisfy me for a while. If I have to use coax I will but I'll try
the easier options first. This basic plan does involve a 10:1 ratio in
windings on the far end toroid which should help smooth out peaks of
resonance as described by John Doty and others as mentioned before, and if
nothing else, drives a stronger current in the balanced line part of the
system.

This is the doohickey I spoke of. It is basically the refuge
accessory of the lowfers where the span of frequencies is, maybe,
three to one and not like the ten to one of HF SWLing.

I'm no longer much concerned about matching impedances, but I will be
watching for results of changing antenna length if resonance seems to be an
issue.

This is at cross purposes. You don't have many realistic options of
changing antenna length (height) as you do with a simple tuner when it
comes to matching.

My interest in the 'doohickey' or any other widget was mainly in what
appeared to be a means of reducing the difference in signal strength extremes
due to resonance. I understand that if I subsequently have to select the
weaker of two close stations I'll either have to add some 'trap' for a
specific offender, such as a trimmed lengh of unterminated coax (though as
far as I know, that trick is usually reserved for much higher frequencies),
or use a manually tuned system which I'll explore if it becomes a dominant
concern.

Traps don't work very well for adjacent AM/SSB stations, you need
cascade XTAL ladders to do that. Tuners, also, can only operate
within the combination of number of reactive elements and Q.

Please respond to your perception of the problem of INTERMOD as it is,
as I said, the silent killer of reception.

73's
Richard Clark, KB7QHC