N4CF antenna 160M upgrade

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Jan. 28, 2017

The desire to participate in contests on the 160-meter band led me to investigate how to make my 80M-6M Carolina Windom antenna operate on 160M. The Radio Works sells a 160M version of the antenna, so I checked its website and saw that antenna is the same as my 80M version, but with legs 99' and 33' longer. The vertical radiator is the same 22' length.

I cut #22 insulated hookup wire to the required lengths, then soldered an alligator clip on one end of each. I lowered the antenna, sanded off the oxidation from the wire, looped the hookup wire through the insulator, and clipped on the alligator clip. Then I hoisted the antenna, secured the extension wires to hearby trees, and went inside to test my work.

The initial tests looked good. The K3 transceiver could tune the antenna with a 1.8:1 SWR across the entire 160M band. Not only that, it tuned it achieved nearly a 1:1 SWR on the 80M-10M bands.

I decided to make the modification permanent. Calculations indicated that shortening each extension would improve the 160M SWR. So I lowered the antenna, cut off 3' and the alligator clip from each extension, and soldered the extension to the antenna wire. Then I hoisted the antenna one last time, and tied-off the extension wires.

I'm pleased with the result. The The K3 transceiver now tunes the antenna with a 1.5:1 SWR or lower across the entire 160M band. Actual performance in the first hours of the CQ 160M contest was encouraging. I made 90 contacts in the first 90 minutes, and worked stations across the US and into the Caribbean, plus one in Morocco.

Updated March 4, 2018