[TowerTalk] Green Heron RT-21 Offset

[Grant Saviers]

I found a similar problem in trying to cal a Yaesu G-1000 on an RT21.  A 
large number of tries using the manual procedure still had significant 
error in the readout vs actual azimuth for significant portions of the 
compass.

Removing this rotator and bench testing revealed that the 500 ohm pot 
that provides the G-1000 position voltage that the RT21 digitizes was 
not correctly installed or was damaged.  The G-1000 has a hard stop at 
CCW 180* (if north centered).  The pot reached its zero limit value well 
before the rotator stopped turning, determined by using the Yaesu 
controller (could also be tested with an ohmmeter and DC supply).

So the RT21 interpolation of CCW 180* and CW 180* digitized voltages 
would not work.  The Yaesu "overtravel" feature can further confuse what 
is wrong.

A rotator with a reed switch for turns counting would not have these issues.

My G-1000 is sitting for a bench disassembly.  The Yaesu pot is not just 
any 500 ohm pot as it requires rotation that exceeds the usual 
mechanical limits of standard pots.  I don't remember that value but 
know it exceeds 300* but it is not a continuous rotation pot.

Of course if antenna or mast are slipping that problem needs fixed first.

Grant KZ1W



On 5/23/2022 06:09, john at kk9a.com wrote:
> I'm sure that W2FU could give much better advice but I believe offset is
> where your rotator stops, most of us use south.  Hy-Gain rotators have
> switched stops in them so if the antenna is not aimed properly it will no
> longer be stopping on south plus if something is slipping it will continue
> to do so until that issue is resolved.  For my rotators with pulse counters
> and no stops I simply turn the antenna true north and set the control to 0.
> For my rotators with potentiometers and no stops, I do a calibration however
> this will only work if the pot is close to midrange when the antenna is
> north.
> 
> John KK9A
> 
> 
> 
> Kim Elmore N5OP wrote:
> 
> I've determined that my antennas point a fair bit east of the direction
> indicated on my RT-21. Rather than rent a lift and readjust them, can I set
> a general offset bias within the RT-21? I'm confused by what the "offset"
> does based on the manual. My rotator is a T2X, but I can't imagine that
> makes much difference.
> 
> Is there a setting that does what I want?
> 
> Kim N5OP
> 
> "People that make music together cannot be enemies, at least as long as the
> music lasts." -- Paul Hindemith
> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk