[TowerTalk] Antenna Rotor Speed

[Jim Hargrave]

Roger,

Normally I would agree with your suggestion. However, the RotorEZ circuitry
is designed to operate using the conventional feedback pot with the wiper
grounded and each end of the pot is a feedback line going to the processor.

The center of the pot is grounded and each end is fed with +5vdc through a
resistor. Each end must produce a range of approximately 0v to +4v to the
processor. One end must be at 0v while the other is at full 4v. These
numbers are reversed when going to the other stop. in practice the voltage
does not actually have to reach the exact ends because the unit has
calibration references to compensate for slight variations on both ends of
the rotation.

I'm sure circuitry could be designed to provide the correct voltages from a
multi-turn pot, but I did not want to modify the basic circuitry of the
controller. With the gear ratio I incorporated, the pot stops about 5
degrees past each end limit. Then with the spring loaded arm, it will go
several more degrees before the spring arm would disconnect. This setup is
easily within the range of the RotorEZ calibration adjustments.

Besides I already had a nice sealed 500 ohm wirewound pot in my "Treasure
chest". So I built around it mechanically.

     73's Jim
      W5IFP




> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com]On Behalf Of Roger (K8RI)
> Sent: Friday, September 03, 2010 12:08 PM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Antenna Rotor Speed
>
/snip/

> Just as a suggestion, if using a pot like this, why not use a 3 turn or
> even 10- turn and calibrate a section to use for the 1 or 1 1/2 turns
> made by the rotator. The old Prosistel PST-61 used this scheme and it
> works very well. With the rotator only able to make 1 to 1 1/2 turns and
> using 1 to 1 1/2 turns on a 3 turn or 10 turn pot gives a bit of safety
> margin.
>
> For gears in the past I've used bicycle racing gears (Chain Ring) and SS
> chain
> Matter a fact I have several spare chin rings and SS chains.
>
>
> 73
>
> Roger (K8RI)
> http://lists.contesting.com/mailman/listinfo/towertalk