Based upon an EZNEC model of a 102’ doublet in free space and varying the
copper wire size, the efficiency and loss in dB for #20 wire is 97.1% with 0.13
dB loss, #24 is 95.4% with 0.2 dB loss, #28 is 92.7% with 0.33 dB loss, #32 is
88.4% with 0.53 dB loss and #40 is 71.1% with 1.5 dB loss. This is based upon
the Average Gain Test for 500 watts power at 7.1 MHz. Losses don’t change
significantly at 28.4 MHz (actually decrease some).
Like others said, mechanical strength is probably the limiting factor, not IR
loss
Steve, W3AHL
---------------------------------------------
Date: Sat, 2 Dec 2017 22:00:59 +0000 (UTC)
From: Gary Slagel <gdslagel@yahoo.com>
To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: [TowerTalk] guage of wire for 500 watt antenna?
I'm hoping to get to Belize to work ARRL DX CW contest this year and I'd like
to take my Elecraft KPA500/KAT500 and operate 500 watts.?I will be at a friends
house and not next to the ocean so I'm thinking of getting a doublet up in the
air as far as I can on a fiberglass pole, feeding with 450 ohm ribbon and
tuning it on 10 thru 40 and maybe 80M.?
The fiberglass pole won't take too much weight so I'd like to go as small as I
can on the wire.? ?Any suggestions or input?
Thanks,?Gary?KT0A
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