February, 2006: I built a half-sized, end fed halfwave for 160 with
plans to use it during the ARRL 160 meter SSB contest. It would
have been my first ever transmissions on this band. I planned to set up
portable and lift the 123-foot wire with some helium balloons and
operate in the QRP category. Long story short is that I drove 50 miles
round trip to buy two 36" balloons from the only store in the Denver
area that still carried the large latex balloons. Two was all I could
carry in the bed of my pickup under the two large boxes I brought
along. When the store tried to inflate them, they burst after
about 30". After getting them home I discovered I actually needed three
of them. Then, one burst within an hour. Oh, well. Maybe next year I'll
rent one of those big helium tanks and find a four-foot weather
balloon. The alligator clips are used to short out the coils. That makes the
antenna a full-size halfwave on 80 meters.
Since none of my match units would tune down to 160 meters, I built one from scratch. The general design was taken from the Fuchs Antenna project
I redesigned it to work down to 160. Here is the schematic I came
up with. Note: I did not need the second, fixed capacitor and left it
and S-3 out.
The tuning capacitor is from an old AM radio, and the toroids are a T80-2 and a T106-2 from Amidon.
Here are the coils before installation.