I recently built a 80 double extended zepp using the HamCalc configuration.I
cut the lengths for 3.555 MHz. Hoping for a broader multiband performance with
a tuner. The lengths are as follows...168.4 ft for each top leg and 38 ft of
450 ohm ladder line for the matching section and then into a 1:1 current balun.
My question is should the swr be 1:1 for the design frequency, is it
attainable, or are double extended zepps inherently a high swr antenna. It
currently runs about 5:1 without the tuner and goes higher on the other bands.I
have not done any trimming or adding to the antenna lenghs. The information
says to trim the ladder line matching section for lowering the swr. Another
source I found said that the ladder line matching section should be cut at 30
ft.
I see a couple of options; scrap the balun and coax and run ladder line
directly to the tuner, start trimming the ladder line (what is a reasonable
amount per test?), scrap the antenna entirely and put up something else. I
recently built a 40 meter loop with 72 ohm matching section and it worked
perfectly 1:1, at its design frequency. I have a fair amount of room to put up
wire.
Your thoughts are appreciated.
Tom KC0PYK
KC0PYK
Thomas Rieff
2059 Sundance Lane
North Mankato, MN 56003
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