[TowerTalk] Emotator Rotator

[Joe Subich, W4TV]

> Information on Emotator is very sparce, but this one uses 28V AC and 
> the rotator has two windings with a common point. Voltage is supplied
> between the common point and either one of the windings. There is a
> capacitor (of unknown value) between the two directional inputs. My 
 > latest thought was that perhaps this capacitor was faulty.

The most common reason for sluggish turning of AC motor based rotators
is, in fact, the capacitor.

The one Emotator manual for an AC motor unit I can find on-line lists
a 6.5 uF cap (for a 100V! motor).  HY-Gain, on the other hand, with a
26 V AC motor lists a 120 - 140 uF @ 50V cap.

You might be able to hang an external cap across the CW and CCW leads at
the back of the controller as a diagnostic measure (Hy-Gain's cap is in
the controller).  If the unit turns properly with the external cap, you
can leave it there until things warm up and you can open the motor unit
to determine the proper value.  For diagnosis, I's use a Hy-Gain/CDE/MFJ
cap but anything in the 100 uF/50V or higher range should work for
testing.

> Looking at the waveforms on each of the inputs show that they both 
> have sine waves (of the same amplitude) with about a 90 degree phase 
> difference, and that this phase difference is reversed when direction
> is changed.
That is correct.  However, if the cap is bad the undriven winding will
be starved for current and the rotation will be sluggish or the motor
will not be able to start.

73,

    ... Joe, W4TV

On 2/9/2024 4:15 PM, Roger Parsons via TowerTalk wrote:
> I have been using an Emotator rotator and 1105MS controller for quite a few years, generally successfully. However, for the past several years it has not rotated when the temperature has dropped below about -10C.
> 
> My first thought was to put in low temperature grease, especially as this had not been changed for many years.This made zero improvement. I then wondered if the connections had gone high resistance. Measurements indicated that they had not, although I wasn't able to measure the resistance of the connector on the rotator. I parallelled several wires in any case, but this also made zero improvement.
> 
> Information on Emotator is very sparce, but this one uses 28V AC and the rotator has two windings with a common point. Voltage is supplied between the common point and either one of the windings. There is a capacitor (of unknown value) between the two directional inputs. My latest thought was that perhaps this capacitor was faulty. Looking at the waveforms on each of the inputs show that they both have sine waves (of the same amplitude) with about a 90 degree phase difference, and that this phase difference is reversed when direction is changed. This seems correct to me, but I would much appreciate any other thoughts.
> 
> Because I've run out of ideas! Of course, I can't actually do anything about it for several months until Northern Ontario gets a little warmer.
> 
> 73 Roger
> VE3ZI
>