I roll my own, with aluminum 4" OD irrigation pipe. The first one was 70', no
top loading, with matching networks at the base for 40, 80 and 160. See my
article in Ham Radio May 1984. The 80m network was a single series 600 pf
capacitor and the antenna covered the whole band. L networks were used for 40
and 160.
40 is narrow enough to cover the whole band. On 160 one network will cover
only a small part of the band, so used a screwdriver motor to drive a rotary
coil to tune on low power for low swr in any part of the band. After getting
the 160m bug, 70' was not enough, so went to a 90' vertical, with portions of
the top guys being wire for top loading. With that it looks like a quarter
wave vertical electrically. Two L networks cover all of 160m. For 80m I use
the screwdriver motor rotary coil to tune for desired part of the band.
Could have added a 40m network, but have a lazy-v for 40m.
177 countries on topband, but not many this year! 73 Bob W7LR
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