R: R: [amsat-bb] More Kansas City Tracker Questions

["i8cvs" <domenico.i8cvs@xxxxxx>]

Joe,

My 2" selsyns motors are very big , the shaft is running on bearings
and they comes from surplus radar and gun applications on now scraped
battleships and so i could use a pendulum arm 20 cm long and an iron
pendulum weight of  3 kg

Year ago i made the experiment to immerge the freely moving weight in to a
large can full of  high density oil to damp the swing  and it worked
perfectly but it was complicated for maintenance purposes because of rain
fall in to the oil and it was not needed for my manual tracking purposes.

In a separate mail i have sent to you the picture of my antenna and you
can see the big arm and big weight of this elevation selsyns motor.

Obviously capacitors to damp the swing don't work with selsins motors
because they operate with 50 Hz  AC voltage

73" de i8CVS Domenico


----- Original Message -----
From: Joe Leikhim <jleikhim@nettally.com>
To: i8cvs <domenico.i8cvs@tin.it>; <amsat-bb@AMSAT.Org>
Sent: Thursday, December 05, 2002 5:17 AM
Subject: Re: R: [amsat-bb] More Kansas City Tracker Questions


> I was thinking of mounting the pendulum in an enclosure to solve the wind
> problem and use a capacitor to dampen the oscillation (I guess the
capacitor
> won't work with your selsyns!) But the enclosure will limit the length of
the
> pendulum arm.
>
> i8cvs wrote:
>
> > Joe,
> >
> > For indication of elevation i use a 2" selsyng motor with a weighted
pendulum
> > and for azimuth indication of rotation i use another 2" selsyng motor by
> > direct mechanical connection to mast.
> >
> > Two receiving selsyng motors in the shack are indicating  the AZ/EL
angular
> > position in two compass with 20 cm diameter and the resolution of the
> > pointers  is better than 0,5 degrees and this is OK for my 1.2 meters
dish at
> > 2401 MHz for AO40
> >
> > The AZ and EL  AC motors are driven CW-CCW and UP-DOWN respectively by
manual
> > operation about every 15 minutes.
> >
> > It would be possible to use the receiving selsyng signals in to a  close
loop
> > servo mechanism to automatically command traking with a PC but
unfortunately
> > the weighted pendulum signal is the limiting factor because the weighted
> > pendulum oscillates and swing everytime you rotate for azimuth and
because of
> > any very soft wind !
> >
> > In conclusion the weighted pendulum is not recommended for automatic
tracking
> > systems.
> >
> > 73" de i8CVS Domenico
> >
> >
>
> --
> Joe Leikhim K4SAT
> Jleikhim@nettally.com
>
> "Jazz is not dead.  It just smells funny." -F.Z.
>
>











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