Our FD group acquired a used Cushcraft A3 yagi. We downloaded the manual for
the A3S from the Cushcraft/MFJ web site, and dimensioned the yagi elements for
mid-band resonance. We temporarily assembled it atop a 35 foot wooden
scaffold/tower to measure SWR and bandwidth. Despite dimensioning it for
mid-band, the antenna shows lowest SWR at the very bottom of 20M and 15M (14.01
and 21.07 MHz respectively) and at 28.15 MHz on the 10M band. The feedline was
a 42-foot length of RG-8X, with a W2DU-style "choke balun" at the feedpoint.
What we noticed when we dimensioned the elements of the A3 was that the overall
length of each element was not what the A3S manual said it should be, despite
each band's measurement being double-checked and verified as spot on. I'm
guessing that the length of the trap housing is different between the two
antennas, but that's just a guess.
So, does anyone have a manual for the A3 (not
A3S) and can you
provide me with the dimensioning info from it? Many thanks.
K3AN
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