Jack's suggestion is a good one. If there IS interaction, what happens
when disconnecting that feedline will strongly depend on the length of
the feedline between the antenna and where you disconnect it.
Our contesting trailer for county expeditions and FD has the feedpoint
for 80, 40, and 20 antennas within about 3 ft of each other. We run 500W
from a KPA500 on each station, so we have double stubs on both the 40
and 80M feedlines, optimally placed on each feedline with respect to the
antennas. That placement is discussed in great detail on my website, in
a piece published by National Contest Journal, and with a pdf of slides
for a talk I've done at Visalia, Pacificon, and to several clubs.
k9yc.com/publish.htm
When two antennas closely spaced antennas are related by their second
harmonic, the lower frequency antenna can screw up the pattern of the
higher frequency antenna. It so happens that the optimally placed stub
nearest the antenna is also optimally placed to kill that pattern
distortion!
73, Jim K9YC
On 9/4/2024 1:16 PM, john simmons wrote:
How about opening/shorting the 40M feedline whilst testing 15?
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