The following two steps seem to have solved the problem I had on 75 meters,
at least when running the Orion barefoot.
1) Ran #12 wire through the 2nd-story window sill and down to a 10 feet long
copper clad ground rod. The length of the wire run is about 15 feet. While
this may seem to be an obvious step, at my previous QTH the use of an earth
ground made RF feedback problems worse on some bands.
2) Installed an Amidon FT-240-77 ferrite toroid as a common-mode choke (11
turns) in the Orion's DC power supply cable and located about 18" from the
Orion. I am using an Astron RS-35A linear power supply (the fan on the
Ten-Tec switching PS was too noisy). The cable run between the power supply
and the Orion is somewhat lengthy because the Orion is connected to an
MFJ-1129 multi-outlet strip.
Step 2 above seems to have also corrected an occasional "flakiness" in the
operation of some of the front panel controls, which I had blamed on
progressive failure of the RIT/XIT encoder. For some inexplicable reason,
the computer problem I had with the USB connected keyboard has disappeared
with the installation of the Orion's power supply cord toriodal filter!
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