[TowerTalk] Determining "True" Resonance of Verticals

[n0tt1@juno.com]

Hi Gentlemen,

This isn't exactly tower talk...maybe close enough...

I have tried several methods to measure *resonance* of a
vertical 20m antenna (which will become a multiband
trap vertical).

In tuning a antenna, I consider resonance and impedance
two separate subjects.  Lowest SWR to me doesn't mean
"resonance".  At this point in testing I don't really care
about the "input" impedance at the coax connector...the
antenna will be matched to the line later.

I have made many measurements using a GDO and a
MFJ 259-B analyzer and I get different readings of
resonance depending on what method I use to couple
RF to the antenna.  When I used the GDO, the frequency
was monitored with a frequency counter of known accuracy.

I'm thinking that the lowest "X" (reactance) indication
on the 259-B would be THE resonant frequency, and
that I should connect the instrument with the shortest
possible leads (like a double-male coax connector)
to the "input" of the antenna.  Is this correct?  Or what
IS the best way?

BTW, the "X" reading has been 6 to 7 ohms with the
259-B and "X" will read zero when the 259-B is
terminated with a 50 ohm load.

73,
Charlie, N0TT


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