On Fri, 15 Oct 2010 09:24:15 -0400, Mike Coslo wrote:

Initial idea is to run the separate wires as taps on the coil. I'm
intending to run them on the outside of the coil, probably separated
about an inch away. The wires would then go to a (insert whizbang gadget
here that I'm still figuring out) which then switches taps as needed.
I'll probably start with manual switching.

Hi Mike,

A rare confab of actual antenna design details. No controversy. No
wonder there are so few postings. Mike, on this cat walk of
fashionable posing, you are a buzz-kill.

How long are those tap wires? In other words, is this manual switch
sitting on your dashboard?

There is also the matter of
that tuning coil at the bottom of the antenna to ground, which varies
between 8 turns of number 12 on a 1.5 inch diameter coil on 75/80
meters, to no coil at all on 20 meters, which is the highest frequency
it will tune at.

Why have a coil there at all?

The antenna itself is semi-standard bugcatcher, a four foot bottom
section, followed by the six inch coil, (standard GLA systems) followed
by another roughly foot and a half section, then a 16 inch Capacity hat,
then a spring and topped off with a 102 inch whip.

Uh-huh. So you have a "top" hat that is actually very close to the
center? A center hat as I might be wont to describe it?

I've often thought (and probably modeled at some point in the last 20
years) about putting such "top" hats at regular intervals along a
vertical radiator. Sort of like a bottle washing brush kind of
design.

Taps at the present
short out the remaining coil below themselves.

Back when we had more designers writing here, instead of Xerox junkies
and home-spun Platocrats, the discussion of shorted coils made them
apoplectic where those turns became huge losses. This is different
from the screwdriver approach which shields those turns.

Anyhow, I pretty much assumed that there might be some small tuning
differences on the lower frequencies,

Well, as I inferred, IFF you knew what frequency any unadorned
(unchanged) original design was going to reside at; then I could well
imagine it would shove that understanding under the bus. IFF, on the
other hand, you have no idea (other than a general one of plus or
minus one MHz) of where the initial state of tune was, then it
probably wouldn't matter.

but I was just making sure that I
wasn't running the road to perfidy with any hidden "gotchyas" - like if
a stinger goes too far into a loading coil - one of those things that
might not be completely intuitive until after the fact.

But of course you will (I'm looking forward to those stories) -
otherwise you would have bought an antenna with a guarantee. In
regard to this last I have to tailor a quote from one of my favorite
authors, Walter Mosely:
"...you won't get to enjoy the honey,
if you worry the bees be stingin' you."

73's
Richard Clark, KB7QHC