Topband: 33', 50', 60' inverted "L" comparison assistance request
ac6dd at yahoo.com
Wed Nov 29 13:05:45 EST 2006
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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