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[Towertalk] GP on a tin roof - a cautionary tale

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Subject: [Towertalk] GP on a tin roof - a cautionary tale
From: (Pete Smith)
Date: Mon, 26 Aug 2002 07:52:11 -0400
I just installed a Butternut HF9V on the galvanized steel roof of my 
garage, using the roof in place of radials.  Just a couple of things I 
thought people might find worth knowing:

-- I could not use my MFJ 259B at the base of the antenna (standing on the 
roof).  Readings were wildly dependent on where I was holding the meter, 
whether my hand was on the case or not, etc.  Evidently standing on part of 
the antenna is not recommended.

-- Resonances on the higher bands are quite far off nominal, presumably 
reflecting the difference between the roof and a normal radial 
arrangement.  15M is 'way high, while 10 is 'way low.  20m still centers 
around 13.9 MHz, but SWR in the band is acceptable.  I WAS able to adjust 
80 and 40, but what with needing to get down off the roof every time I want 
to measure anything, I haven't sorted out the other bands yet.

By the way, performance is quite adequate.  Ran a few comparisons to Europe 
on 20m last night, and it's down 6-12 dB compared with my stacked 
tribanders, although QSB was also quite a bit worse on the vertical.  It 
also is only down a few dB with domestic stations on 40m, compared to my 
yagi at 104 feet.  Presumably both antennas are too low-angle for this 

73, Pete N4ZR
Sometimes a tower is just a tower

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