JLB wrote:
Hence my question. Are we? I recall that a 5/8 wave vertical was
'close' to
50 ohms at the feed point and could be 'adjusted' with an inductance
across
the feed point (with the feedline at a tap perhaps?).

Tuned to an electrical 3/4 wave...Basically, just tuning out the
reactance..

That is the whole
point is using such a 'magic number' as 5/8 wavelength.

Huh? The point of the 5/8 radiator is pattern and gain related, not feed
impedance, or matching.

If you look at the
impedance curves, though, you find that they are quite steep at this
point,
so a small error in length causes a large error in impedance, and some
tuning will be needed. The 5/8 wave is not a 'build it and go' antenna!

It's pretty close to it though. All you have to do is start off with a
"best guess" coil and test. If it's resonant low in freq, take turns
off. One at a time, if close. If it's high in freq, you need more
turns. Not really any more complicated than trimming a dipole for
resonance. After building a lot of those, I can guess the number of
turns needed in my head and come pretty close. Reg's guess of 13 turns
is pretty close if the form is 1-1.5 inch wide. Using my built in
guessing machine, I would have quoted appx 15-16-17 turns off the top of
my head , if the coil is made of #12 solid wire, and wound on a 7/8 inch
pipe former, "I use a piece of 7/8 inch copper tube as the former" and
then taken off the form. "On those type of coils, I make them self
supporting. The #12 wire is stiff enough to hold it's shape. Just
connect and clamp each end of the coil to hold it in place. MK

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