We are setting up an active Amateur Radio station at Colorado's
"Wings Over the Rockies Air and Space Museum" here in Denver. We
are currently installing a Hustler 6-BTV Vertical on the very
large metal roof of the hangar which is about 40 to 50 high, but
are having difficulty with proper tuning.

We initially assembled the antenna with the following dimensions
(in inches) according to the manual:

A = 1, B = 1-5/8, C = 1-1/16, D = 1-1/2, and E = 1-1/2

The mast and metal roof are well grounded and show continuity
between all panels. The mounting bracket had to be placed 24"
above the roof and, although the mast/bracket/roof are grounded
and bonded, we have placed a grounding cable from the mounting
bracket to the roof.

We have also made the 6" RF choke coil, however, SWR measurements
are not significantly different with or without the coil OR with
or without the ground cable.

Initial measurements with an MFJ Antenna Analyzer show that the
lowest SWR measurement is significanly below each of the band
segments.

For instance, our measurements on the 10-meter band we

SWR dipped to 1.5:1 at 25.9 mHz with the 72" tube fully shortened.
SWR dipped to 1.6:1 at 25.8 mHz with the 72" tube extended 1",
SWR dipped to 1.6:1 at 25.7 mHz with the 72" tube extended 2",
SWR dipped to 1.5:1 at 25.6 mHz with the 72" tube extended 3", and
SWR dipped to 1.5:1 at 25.4 mHz with the 72" tube extended 4".

According to those measurements we would have to cut over 30" from
the 72" tube to get to a tuned frequency of 29 mHz.

That does not seem right, so I would appreciate any comments or
suggestions to help make this antenna work.

73,

KB6CC