I have used various inverted L configurations in my portable 160m contesting.
The vertical sections were at one time or another 19', 33', 37', 50', and 60'
tall. Also a 90' top loaded vertical was used a few times. They were all used
over very good ground (salt water). I stopped using the 90' top loaded
vertical because of the effort it took to put the antenna up. I came to the
conclusion my radiation angle was too low. I now use a 50' tall inverted L to
cover as wide of a vertical angle as possible (it was 60' but the dropping top
wire got snagged by a truck and a section broke). The shorter vertical
sections worked as well, but conditions had to be just right. I worked all
kinds of DX with the 19 footer during one contest (115' sloping section). A
35' tall inverted L was used in the last Stew Perry with good results. During
the last CQ160 two phased 33' tall L's turned out to be just too short, and it
was a struggle a lot of the time.
I was thinking about using the top loaded 90' vertical again, but using a
vacuum relay to switch it into an L configuration as needed.
By the way I use a tapped unun wound on a FT240K core for matching the
inverted L's. The 30 footers match on the 12.5 Ohm tap, the 50 footer on the
28 Ohm. The 90' vertical's pattern was very narrow, so I had to use a Harris
RF601A automatic coupler to cover the band (until I burned up the discriminator
circuitry). The 19 footer was matched with the Harris coupler in manual mode
(still burned up) with added external capacitors at the antenna terminal.
This is a second try to reply to this post, the first one a week ago
apparently never made it.
Niko - AC6DD
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