Greetings to fellow Ten-Tec enthusiasts!
A few months ago, I replaced my Kenwood TS-850 with an Omni-6. I'm very glad I
made
that choice (I don't say this lightly, because the 850 is a very nice radio).
The
Omni-6 has been masterfully engineered, and we're fortunate to have such a
company as
Ten-Tec in our country.
Now for the problem.... When I pulled the TS-850 out, I put the Omni-6 into
the empty
slot. Then I hooked up my computer (25 pin serial port), key, Heil mike,
external
speaker, antenna (via SB-220), and a footswitch to the Mute & PTT jacks. It
checked out
on CW just fine. When I tried it on SSB, it worked OK on 160, 80, & 40, but
had RF
feedback in the audio circuit on 20 and 15.
Here are some observations:
1) The feedback was power sensitive--as I decreased the power, the feedback
decreased.
2) With my SB-220 engaged, the feedback was unbearable.
3) When I connected a dummy load (either directly to Omni-6 or with SB-220
engaged, the
feedback stopped).
4) The feedback was the same with either an R7 or a longwire connected.
5) The feedback was so bad that it would motorboat with mike disconnected (if
the mike
gain was turned up high)!
6) I did not have the problem with the 850.
7) I tried several different mikes, including the Ten-Tec.
I have a good, low impedance, single point ground to which all of my equipment
is
connected. I rebuilt my operating desk to put more space between the SB-220
and the
Omni--no help.
Finally, I removed each connection from the Omni, one at a time, checking for
the
feedback. When I removed the last one, the computer serial interface (25 pin),
the
feedback disappeared, and the audio was beautiful.
As per the Ten-Tec manual, I was using a commercial serial port cable, about 5
feet
long (I had been using a homebrew interface and homebrew cable on the 850).
Before I
make up a new cable (the old fashioned way) and proceed with the resolution of
this
problem, I decided to ask you fellows if you have been down this path. (Is the
answer a
new cable, isolation, filtering?)
Thanks for any comments you may have.
73, Dan - W4TQ (Dunnellon, Florida)
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