[Elecraft] [OT] High SWR on 20 and 40

[Guy Olinger K2AV]

There are many kinds and configurations of tuners, each one having
differing weak spots.  There is not a single one outside of military
prices which does not have impedance ranges that are inappropriate for
the particular tuner design.  Some tuners use CONTINUOUSLY variable
inductors AND capacitors to get around most of those "blind spots" but
there will still be matching points where it can't be brought down.
Often where circulating currents in that particular design MUST become
so high as to destroy components or waste half the power or more .

You can fit a hundred KX1's inside of the case of many tuners, so in
the KX1, the overriding issue is to use a design that CAN be
MINIATURIZED. That you have an auto tuner AT ALL in a KX1 is already
on the wonderful side of remarkable.  To criticize it for not having
the range of a larger tuner with continuously variable components
seems unfairly critical to an extreme.

Tuners designed with switched components necessarily have a "lumpy"
performance but are the only method that can be made small enough for
internal use in a K2 or KX1, etc. None of these that I have seen will
deal with 1000+ ohm loads.

But the real root of the calling these no-match ranges a "problem"
seems a lacking in basic antenna understanding.  ANY wire with ANY
feedpoint will have harmonically related frequency ranges where the
feed impedance can go into the thousands of ohms. If you have put up a
wire antenna for all band use and haven't MEASURED what these are for
your antenna on intended frequencies of use, you are quite short of
putting forward a reasonable case for a tuner not working or having
poor design.

Loading any antenna to all ham bands in any location with any
miscellaneous conductors around REMAINS a very sticky problem.  For
sure, NOT among god-given rights, is that any auto-tuner in any rig
(including a KX1) must able to tune ANY antenna to ALL bands in any
circumstance and provide a 1:1 SWR.

There is an antenna, manufactured for decades by B&W, that is a folded
dipole with with a feedline on one wire at the center, and a high
power RF termination resistor on the other wire at center.  The
termination resistor prevents the nodes of very high feed Z, reducing
the range of Z extremes to values easily matched across the spectrum.

There are tens of thousands of these antennas in use over the world at
military sites, embassies and other installations where frequency
agility is important, particularly in spread-spectrum modes. The
"wasted" watts on certain frequency ranges are made up for by removing
the high-Z nodes at the feedpoint. That this is an entirely successful
approach and design fulfilling a continuing need is proven by
continued sales to this day.

Designing a single antenna that does not have Hi-Z nodes on
wide-spread wanted frequencies is a pastime that goes back to the dawn
of radio, and continues to this day.  G5RV's, 86 and 43 foot end-fed
wires, off-center fed dipoles, are but a few of the answers, and each
has characteristics here or there that make it unusable or less
desireable in a given circumstance.

If you can't match it, START WITH THE ANTENNA, THEN THE FEEDLINE.
Random collections of elevated wire and feedline usually DON'T work
everywhere. But if it doesn't work and you don't get it, you have a
challenging and possibly highly entertaining education in front of
you.  Something like learning to play chess.  Join the century-old
society of antenna designers and tinkerers going back to Marconi and
beyond.

Dumping it on tuner manufactures is just so ......

Never mind.

73, Guy.