[TenTec] "A low vswr will kill you ! "

[Dr. Gerald N. Johnson, electrical engineer]

My tuner uses the parallel secondary connection that Cebek reports for
some antennas and feed line lengths and the series connection for
others. With 1/4" edge wound strap in the coil, its easy to connect for
various bands and connections with alligator clips.

I use the tapped secondary coil connection for single band tuners. The
Johnson Matchbox uses differential capacitors to accomplish a front
panel variable set of taps, but with reduced range. I tend to not use my
Matchbox at home because it tends to not have the range needed for
antennas in use here.

The Harvey-Wells Z match uses a universal multi band tuner (originally
sold by National or Millen for PA grid circuits and plate circuits) that
has two coils and so two links. Some report it to have a good tuning
range. The problem with the multiband tuner is that its loaded Q varies
wildly over its frequency range (as does its L/C ratio) and that will
mean that its load range will be different on different bands. That's
true of band switched (or plug in coil) tuners but not to the same
extreme. Because of the size limitations for coils and capacitors, most
tuners don't tune as wide a range on the extreme bands (160 or 80 and
10) as they do in the intermediate bands. Especially when the antennas
are reactive which the tuner has to counteract to come to resonance.

The "power" meter with the matchbox is not a power meter, just a SWR
indicator. It is frequency sensitive. I quit using mine a like a
heathkit better though its not as good as the Collins rejected prototype
in my main tuner.

One might have to make an air core balun by hand by winding parallel
wires. Its not much more than a couple coiled up fairly closely spaced
parallel wire transmission lines. Probably #16 spaced 1/8" wound 2"
diameter and 10 inches long. Two coils and connected by some ARRL
antenna handbook circuit circa 1959 should be close.

73, Jerry, K0CQ

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