[TowerTalk] SteppIR

[Jim Lux]

On 2/28/15 8:33 PM, Richard (Rick) Karlquist wrote:
>
>
> On 2/28/2015 5:46 PM, Jim Thomson wrote:
>
>> ##  whats wrong with installing a shaft encoder on the plane jane
>> DC..or AC
>> motor?    That’s what K7NV  does on his prop pitch conversions..and works
>> slick..simple concept, easy mod to any motor.  Its all fed to the
>> Green Heron
>> box...which is a modified RT-21.
>>
>> Jim  VE7RF
>
> What is wrong with it is unnecessary complexity.
> The SteppIR stepper motor scheme works perfectly, with
> occasional recalibration.  Don't fix it if it ain't
> broke.  The SteppIR antennas have had their share
> of reliability problems, but the stepper motor isn't
> one of them.  They just work, even if other stuff
> in the antenna may not always work.


This is why steppers (or their close cousins brushless DC motors) 
dominate in industrial applications, particular where you need slow and 
stop speeds.  For "continuous run at variable speed", variable frequency 
drive induction motors are popular.




  If there is
> a weak point, it is the controller that operates
> the stepper motor.

I would think that the stepper drivers are vulnerable. Particularly with 
long runs: a lot of inductance, and very sensitive to lightning and 
transients.  The SteppIR remote driver box probably fixes this.. put the 
driver close to the antenna, and use RS485 as the comm link.

A previous TT post (in 2007) said that they use a L6219 chip as the driver.