In a message dated 10/19/01 3:51:42 PM Pacific Daylight Time,
From my readings of things and listening to things, the idea of
near, at, or in the antenna appears to be the best thing to do for most
operation. I have been looking at the screwdriver types of antennas,
even offer a dipole arrangement. I think that the only drawback would
the lower radiation resistance. But I have not been able to figure that
out or the efficiency of tuning in the shack versus tuning at the
for the same size antenna. Then of course for smaller antenna tuning
Chris opr VE7HCB
Chris: A tuner at the antenna has some merit for complex loads but coax
is now the major feedline to the shack. A remote tuner has to be tuned and
I've done it at the tuner with 2 selsyns. You also need a band changing
switch. You are suggesting something that is very inconvenient and slow.
Using a tuner at the antenna admits you don't know how to create 50 ohms with
a matching system like a "T match, Series Xc or Folded Dipole Techniques" for
use in Verticals, Loops or what ever which the tuner is now required to do.
Transfer the task of impedance matching regardless how complex it is to the
other end of very low loss controlled open wire line length--in the shack.
This concept has been around since the Stone Age of the Last Century and has
never been improved on--just hot air RF.
There are places for a Remote Tuner. I have used one at the bottom of top
loaded vertical on the LF's as it was voltage fed there and coax loss is low
on LF for the rest of the way into the shack. Here the nuisance of remote
tuning it was worth it. It was an 80m dipole fed with a 1/4 wave of open
wire line. With the feedline shorted it's an upside down ground plane with a
hell of a low angle. There is a way to get a circular polarization and
controlled remotely. It was described in QST and another Radio Mag I have in
my files in the late 40's. This could be of great value in any contact or
contest on the LF's. This hasn't got any play and it works. It also reduces
QSB from Polarization Shift. You see there are still new/old ideas yet to
use in the year 2001.
In case there are any who have repeatedly missed the message, there are very
simple techniques from the Stone Age of the Last Century where you can match
any Z at the end of an open wire line to 50 ohms in a very low loss, a
repeatable and recordable form. Nobody has found better ways to do it--that
has shown it. I will personally reward anyone that does--with a reward of my
choice, naturally. Hopefully this will inspire someone to give it a try.
One of the main reasons for a tuner is to match the Z at the end of open wire
line preferably of a certain length--to 50 ohms. You let your fingers do the
matching in the shack. The antenna load can be resistive in the middle of
the band or it can be complex on the band edges at the antenna or end of the
feedline. Maximum power can be transferred to either load with the least
loss over the entire band(s) by matching the Z at the end of the open wire
line feedline in the shack which a MB will do.
The open wire line is the easiest to repair if damaged (coax is discarded),
lasts for a lifetime, costs the least of any feedline in particular if you
make it yourself. After the settings are determined and recorded across the
band they can be quickly selected without checking the SWR each time.
Heathkit had a box with a "Motor Driven Series Xc Variable" that was
installed at the feedpoint in one leg of a dipole or inverted vee for broad
banding purposes. Even though it was just in one side it worked just great.
It's "just another example" of where a "Series Xc" has been used to increase
bandwidth over the band "Very Successfully." It can be also used to obtain a
higher Rr value for verticals or L antennas in addition to increasing the
bandwidth--with a single component fixed or remotely tuned. Many seem
brainwashed they have to use a 1/4 wave vertical length when in most cases
the Rt is around 40 ohms. So make it a bit longer and add a fixed series Xc
such that it gives 50 ohms in the middle of the band. "Increasing the Rr" is
a more efficient way to go. Or add a motor or selsyn driven Xc to obtain the
lowest SWR over the entire band. Use the MFJ SWR Analyzer and a variable to
determine the value--fixed or variable.
This should be standard practice in this Century. I keep getting E-Mails
with this basic thread--"I've read your recommendations and finally decided
to try the Series Xc in verticals or L's or the MB and open wire line on and
on and on despite what the Poo Pooers say or those who never try it and--it
works. Why do they do that?" I suggested "they ask them!" Progress is
tough unless the "Professional Poo Pooers" supposedly generate an idea which
is of course very rare. Progress is not their state of the mind.
Regardless how far you look you will never find a more useful technique than
a "Series Xc." In a survey I made, it's now one of the most used by those in
the know. What's puzzling is why it took so long to catch on? I guess it's
too simple to understand and the flee markets are full of choice variable
Xc's at a low price. A variable Xc of the right value can do a lot of things
in a small rotational movement often in less than 30 degrees with a component
with virtually no loss. I will be describing "even more of them." Stay
tuned. Those who "Slam It Repeatedly" do not give any other technique that
is more useful or what they use. I'm still waiting. I'll give credit where
it's due to anyone. I'm looking for new ideas all the time regardless who
they come from. Please send them to me or TT. If you have a better way to
do something--show it. K7GCO
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