[CQ-Contest] Need confidence....
k9yc at audiosystemsgroup.com
Tue Oct 4 23:31:17 EDT 2016
What radios and what separation? What power level? Serious common mode
chokes on each antenna at the feedpoint? Some radios are a LOT better
On our CQP county expeditions, we regularly run two K3/KPA500 stations
into two C3SS on the same band, one on CW and one on SSB, with spacing
of about 200 ft, on 20, 15, and 10, and with no interference. The
antennas are aimed to 70 degrees and are carefully placed with their
driven elements co-linear. We've run two on 40 and two on 80 with
dipoles separated by about 300 ft.
There's a review of multiple bandpass filter sets on my website, all of
which are intended to run between the rig and the power amp. SOME sort
of harmonic suppression filter is needed on the output of power amps so
that harmonically related CW stations don't wipe out the RX of the
station on the higher band. Stubs work quite well for that. See the
piece on my website about that.
This doesn't answer your question about high power bandpass filters or
triplexers, but there are other solutions, depending on your resources
and the constraints imposed by your site.
Another point. Antennas resonant on a single band at a time inherently
help with harmonic suppression because the antenna is badly mismatched
to the feedline at the harmonic. For that reason, the small 2-el SteppIR
is an awfully good choice. It's quite lightweight,and collapses rather
73, Jim K9YC
On Tue,10/4/2016 6:03 PM, Ray Day wrote:
> to activate Santa Catalina
> Island (IOTA NA066) again in February 2017. In the past we've had problems
> with 2 radios simultaneously on 20/17, 17/15, 20/15, etc. We don't have the
> room to be completely "tip-to-tip" with our 2 hexes, nor can we get much
> physical separation between the 2 antennas for the 2 rigs. So - problems.
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