[amsat-bb] Re: rotor replacement pots

i8cvs domenico.i8cvs at tin.it
Wed Sep 17 19:22:18 PDT 2008

----- Original Message -----
From: "mvm" <amvm at skynet.be>
To: "George Burr" <gaburr at magma.ca>; <amsat-bb at amsat.org>
Sent: Wednesday, September 17, 2008 4:05 PM
Subject: [amsat-bb] Re: rotor replacement pots

> Has anybody tried to use other methods of sensing than the pots? I'm
> currently trying an electronic compass. First results are promising.
> Eventually I want to completely replace the Yaesu controller.
> BR,
> --
> /\/\arc
Hi George, ON4AMV

It is possible to use commercially available absolute encoders with
linear analog output from 0 to 5 volt or from 0 to 10 volt for a single
revolution of 360°

The above absolute encoders are more accurate than any conventional
linear 360° potentiometer and they don't use moving contacts like a
wiper built into a wirewound potentiometer.

They are made by Tekel, Eltra, Lika Electronic and many others manufacturers
for robotics and industrial application but they are very expensive.

In addition the backlash into the gears of a G5400 rotator do not justify
such high accuracy and a good wirewound linear 500 ohm potentiometer
represents the best technical and economical solution.

By the way when a very high repeatedly position accuracy is requested
as for large EME dishes then absolute encoders or resolvers with the
associated syncro to digital converters are necessary.

73" de

i8CVS Domenico

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