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Frequency Skips and Sporadically Tunes Down the Band
Problem: The MP would sporadically start
tuning down the band. It didn't always do it, but it would sometimes. Some front
panel settings would affect its tuning down; using the Notch filter in
conjunction with the EDSP would almost always cause the down tuning. It only
tuned down, however, when in SSB mode.
Solution: It appears that Heil wired the
cable adapter for the Yaesu radios incorrectly. The Heil adapter ties the Mike
Ground and the DC ground together and connects them to pin 5, while the pinout
diagrams on page 4 of the MP manual shows that Mike ground goes to pin 7 and DC
ground to pin 5. I rewired the plug per the page 4 diagram, and the radio no
longer tunes down the band by itself. Why did it not tune down in CW mode? When
in CW mode, I always pull out the Heil adapter cable, to get it out of the way.
Why notch and EDSP? I haven't figured that out, but my theory is, by letting
that signal return float, some kind of circulating current was being interpreted
by the radio as an instruction to "tune down"- as though the button on the mike
was being pushed. I originally thought it might be a short in the cable, telling
the radio to tune down, but there was nothing to short that was connected to
either pins 1 or 3. What I can tell you is, since I rewired the cable, it hasn't
tuned down on its own. Dennis NB1B
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