Rick,
The radios used with the double shielded coax were our usual assortment
of radios we use for FD, a Club owned TS 450 for SSB phone, a school
club Icom 707 for GOTA on 40m (sharing with the SSB phone above part of
the time) (GOTA on a half wave 40m dipole about 45 feet from center of
the SSB 88 foot doublet, and at right angles to it. (The ends were
within a few feet). The third (CW) rig in the same room as the above
two was an Icom 756 pro II. Mostly on 20m CW, but also did RTTY. The
SSB phone station was mainly for 20m but moved to 40m when most of 20
available stations had been worked.
With the GOTA station operating at a low rate with new ops or visitors,
we put the responsibility on their coach to pick spots on 40m phone band
where we were not using the other phone station. Thus, same band
interference was pretty minimal. I did not hear of GOTA bothering
either of the other stations.
Interesting that you asked if we had tested the radios before this co-
location. What was supposed to happen was we reserved a room for GOTA
and the SSB phone stations, and the CW /RTTY station was to have a room
unto itself. However, a scheduling mixup had the CW room in use that
Sat., and we had to move CW next door with GOTA/ phone. The good
spirits were with us, and we had no co-location issues that watching to
stay in opposite ends of a band could not solve. CW mostly stayed in
lower 25kHz of 20, or in the RTTY area. The SSB station trolled the
whole SSB sector, and simply moved the opposite of any frequency where
the other stations gave a problem. It was trial by necessity; but I am
glad it worked out so well. Had GOTA had more operators, it might have
been more of a problem, but they had periods with no activity.
I am sure the double coax shields helped some; but the siting of
antennas to space them in directions of least interaction helped as
well. The CW/ RTTY vertical antennas were 125 to 170 feet away from the
GOTA dipole, and 125 to 150 away from the SSB phone 88 foot doublet
inverted Vee.
-Stuart Rohre
K5KVH
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