Here is my FD experience:
Had prepared a muti-fan dipole antenna (paralled dipoles with single
feedline) for 40-20-15-10-6m and tested it at home suscesfully with the
F5Ka.
Problems on Field Day:
Since we were A4 (4 HF stations) we had other stations nearby. I
experienced a lot of baseline-noice pumping (abt.20-25DB) due to overload
from the 40m phone station. (we shared the same tree (on one side) as a
ty-point for our antennas. The antennas were on right angles. However I had
expected this and figured I could just get on another band away from the
40m. However I had the same baseline pumping on 20-15-10 and 6 meters. As
it turned out I could not work any band.
After a lot of head scratching I figured out the problem. Since all the
fanned dipoles share the same feedline, the 40m overload on the front end
was still present at the antenna terminals of the F5Ka no matter what band I
operated including 6m. So the solution was to dump the Fanned Dipole.
I replaced the the multi band antenna with a single band 20m dipole and had
no more overload problems. I started to work PSK31 low in the band and had
no problems, even that a 20m phone stations was transmitting nearby (same
tree shared) about 180KHz higher in frequency. However the joy was only one
sided. It did not take long before the owner of the Icom 756 Pro-III ( the
20m phone station) came over to complain about interference. He now
experienced the baseline pumping on his rig.
Since he ran 100W on transmit and I was doing 75W I concluded that that the
Flex 5K had a superior front end.
Anyone having any specs on these rigs for dynamic range to back this up?
Moral of the story:
Do NOT use a multi band antenna on FD unless you are working by yourself
far away from other transmitting stations!
John, ve3dvv
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