..."I didn't tell the whole story about the 1/4 wave vertical:
it's mounted 30' out in a saltwater river that has a pretty clear
saltwater path to Europe, Africa, and South America. "....
There is a huge difference between a vertical over salt water and one
over average ground, maybe as much as 15 dB at very low angles. With a
decent radial system to get connection to the salt water, the vertical
should beat the XM240 below about 6 degrees elevation (even if the XM240
happens to be over salt water too). From about 6 degrees thru 44
degrees elevation, the XM240 should win.
Or so says EZNEC.
It sounds like the only connection you have to the salt water is the
feedline (assuming you didn't add a choke).
A four square over salt water is a very good weapon.
Jerry, K4SAV
RLVZ@aol.com wrote:
>Guys,
>
>Thank You for the quick replies that stated the "Shorty-Forty should be doing
>much better". That's what I originally thought too or I wouldn't have put up
>the antenna.
>
>Some asked "what type of Shorty-Forty"? It's a new Cushcraft XM-240 that was
>cut for Mid-Band. The resonant frequency turned out to be 20khz higher than
>the chart. (1.2 to 1 SWR).
>Tomorrow I will take a look at the Shorty-Forty with a AIM 4170 antenna
>analyzer.
>
>Since several people indicated that the Forty-Shorty should be working much
>better than it is I need to back track and clarify the ground system of the
>1/4
>wave vertical. I didn't tell the whole story about the 1/4 wave vertical:
>it's mounted 30' out in a saltwater river that has a pretty clear saltwater
>path
>to Europe, Africa, and South America. (I'm about 2 miles from the Atlantic
>Ocean and there are numerous small barrier Islands in between... but it's
>mostly saltwater river) The reason I listed "average ground conductivity and
>a
>reasonable radial system" is because the vertical has no radials and just a
>single corroded ground strap going down into the salt water... and I've been
>told
>that isn't sufficient to connect to the saltwater.
>
>Perhaps the vertical is making better connection with the saltwater than
>expected? If so, would that be the reason the simple 1/4 wave vertical with
>no
>radials is equal in performance to the Shorty-Forty at 90' on DX qso's... or
>do
>you still think I have a problem with the Shorty-Forty?
>
>One more thing, to the West where the vertical does not have a saltwater
>path, the Shorty-Forty is 10-15db better. But since the vertical has no
>radials
>and no saltwater to the West I'd expect at least that much difference.
>
>73,
>Dick- K9OM
>
>
>
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