On Jan 9, 8:24*am, Cecil Moore wrote:


There seems to be developing the myth that a tuner
at the shack cannot accomplish that feat. Although
strictly technically true, a low-loss tuner and low-loss
transmission line can come close enough to achieving a
conjugate match at the antenna that almost all of the
available power is transferred to the antenna (if losses
are made negligible by good engineering practice).

It can be proved mathematically that in a lossless
system, a conjugate match is established at the
antenna feedpoint by the tuner located back in the
shack. A near-conjugate match is established in the
case of a low-loss system resulting in near-maximum
available power transfer to the antenna.
--
73, Cecil *http://www.w5dxp.com

Judging from my mobile antenna tinkering, I'd have to
say that is true.
As an example, with a short run of coax that feeds
the antenna, you would think that it would be required
to place the matching device or tuner at the feed point
of the vertical. And strictly speaking, it would be the
best place for it.
But... I've found that you can have very good results
if the tuner is at the radio end of the coax.
In actual operation, there seems to be little difference
in performance.
But the short piece of coax "maybe 10 ft long" is
fairly low loss on the lower HF frequencies.
So it's not a lossless system, but fairly low loss
considering the frequency and short length of
the line.
But if I run a long coax to the same antenna, I
would prefer to keep the tuner at the same place, in
front of the short 10 ft piece, and then run my long
cable from the radio to the tuner, which is still at
the car.
I often did this when using the radio at picnic
tables, tents, while using the mobile antenna on
the car.
My most recent installs on the two trucks place
the matching device at the antenna.
But in my older car I once used, I used the tuner
at the radio end. It was convenient, and let me
fine tune the match while driving.
There seems to be little difference in performance
that I can see using the short fairly low loss pieces
of coax. Not much difference where I place the
tuner. So this tends to back up your theory.