We used a Butternut HF6V on a large metal roofed county building successfully.
The base loading coil had to be stretched out really long (per the manual's
hints regarding a metal roof) and we eliminated the 75-ohm coax quarter-wave
matching section intended for 20M. The loading coil should be slid over a
plastic tube and mounted securely to stabilize it.
I think a 43' vertical with an SGC tuner is probably a better option, but have
never compared them side by side....
Steve, W3AHL
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Message: 3
Date: Thu, 21 Jan 2010 14:27:26 -0500
From: "David Jordan" <wa3gin@comcast.net>
Subject: Re: [TowerTalk] Hustler 5BTV Problem and their servicing.
To: "'Tower and HF antenna construction topics.'"
<towertalk@contesting.com>
Message-ID: <F17EACE9A87844C1B2EB2B42539790B7@DTSFBXZ441>
Content-Type: text/plain; charset="us-ascii"
Our club mounted this antenna on top of the County Court House roof which is
copper for 100ft in all directions. It won't load worth a damn. I guess it
was never designed to operate over a almost perfect conducting ground plane.
All the bands resonate low in out of the ham bands. We're going to have to
cut the lower most portion to bring them up in freq. That is a good thing
because the lower portion mast is thin-wall soft aluminum which bent the
first time we had over 30mph winds. Replaced that portion and it bent
again. We asked DX Engineering to provide us with a thick-wall mast but no
joy. So, if you are going to roof mount the beast consider guying it at the
mid-point or find a way to beef up the mast below the 10m trap.
We also found that the trap camps do not grip the well using the hose
clamps, in fact the hose clamps fail when attempting to achieve enough
compression to maintain a tight fitting. Not impressed with the current
physical implementation of this antenna.
We're looking for an alternative solution for this wonderful vertical
antenna location. The roof is about 400ft ASL.
73,
Dave
Wa3gin
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