I have a G-1000DXA and a G-800SA for the top and bottom tribanders in my
stack, respectively. Recently the top rotator (the DXA) started to behave
erratically. When I would press the "left" or "right" ends of the control
bar, the indicator would taker off 45-90 degrees and then begin to indicate
very slow and somewhat irregular antenna rotation. I thought I might have
a connector problem, so I cleaned the connector at my entry panel, to no
avail. Then I switched the two controllers, and to my surprise, the
problem 98 percent cleared up (the G-800 controller on the G-1000 rotator
still displays a momentary indicator swing of ~5 degrees, before rotating
and indicating position normally). The G-1000 controller seems completely
normal.
I talked to Jerry Darby at Yaesu, who is pretty knowledgeable about the
rotators, and he said that this was a new one for him. He did say that the
circuits of the SA and DXA controllers that senses the antenna's position
are a little different, so that they might react differently to some sort
of cable problem - excess capacity to ground, for example. I'm not sure
that I can measure that, but I did measure the resistance of the motor
windings and the rotator pots - the pots seem virtually identical, but the
G-1000 motor reads 15 ohms, while the G-800's reads 30. Jerry says that
the motors are the same, so this may be indicative, but he could not
suggest what to look at next.
I have a workaround, described above, but suspect that there is still
something in the cable to the DXA that is haywire. Does anyone have any
suggestions for diagnostic steps I can take, hopefully from the ground?
73, Pete N4ZR
The World HF Contest Station Database
Full details on 3300 contest stations
Updated 5/5/07 http://www.pvrc.org/WCSD/WCSDsearch.htm
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