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Old February 19th 04, 07:12 PM
bb
 
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Default Mark Keith?? vertical

Please describe your vertical in detail.

Does it have to be elevated, # of radials, length of radials, etc.

VK is exactly where I'm trying to go on 40m from the NW US.

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Old February 20th 04, 09:40 PM
Mark Keith
 
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bb wrote in message ...
Please describe your vertical in detail.

Does it have to be elevated, # of radials, length of radials, etc.

VK is exactly where I'm trying to go on 40m from the NW US.


It has to be elevated if you want to avoid many, many radials. Mine
was a standard 1/4 wave ground plane, just like you would see on 2m ,
or any other band. I used an old heavy duty 5/8 CB antenna for
material, and added tubing to make it 32 ft tall. The tubing at the
top was very thin, and the antenna was self supporting.
It used 4 wire radials which sloped towards the ground at about 45
degrees.
The base was mounted on a 36 ft radio shack pushup mast. The radials
also help out as guys. In considering the number of radials, you must
consider the antennas height above ground in wavelength. If you use
the "standard" 120 radials on a ground mount as a benchmark, as you
raise the antenna, less radials are needed to equal this same level of
performance. At 1/8 wave, "appx 15-20 ft on 40m", you need appx 60
radials to equal 120 on the ground. At 1/4 wave, appx 8-10 radials, at
a 1/2 wave up, 3-4 radials. Each of these scenarios has appx equal
ground losses.
So you can see that my antenna at 1/4 wave up, using 4 radials, was
about equal to a ground mount using about 50-60 radials. This is still
quite good performance, but I could have slightly improved by doubling
to 8 radials. That would have given me losses appx equal of the 120
radials on the ground. You put up one like I used or better, and you
will say adios to that dipole on paths to VK land. If you really want
to brown the food over there, put up a bobtail curtain and run a KW.
"I did usually run a KW myself". Heck, even to the west coast, many
nights I'd have guys coming up on freq and wondering what the heck I
was running. They would often say I was the loudest thing on the band
at that time. And thats just at 1500 miles away. You start seeing a
bigger differences the farther away you work. I popped in on a JA
contester one night. Gave him a quick one shot call, and he jumped
right back and said I was 20 over 9 in Tokyo. I think I startled
him....I'd never be able to do that on my low dipole. :/ MK
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