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Re: Fodtrack


     Congratulations on building a FODTrack.  It will provide you a great 
deal of trouble free service once you get all the bugs out.  Generally the 
unit will move the antenna to around 185 degrees Azimuth and 5 degrees 
elevation when you "turn it on" or close the "enable" switch.  I am 
concerned it is flipping the antenna (elevation) on start up.  Here is a 
list of things you may want to check.

1.  Double check your wiring for the connector to the rotor controller.  
There are a couple of different pin numbering schemes for this kind of plug. 
  Be sure you use the one shown in the FODTrack schematic.  Remember that is 
the view looking into the female connector (The one on the rotor 

2.  Launch the FODTRack program and run the calibration portion of the 
program.  Turn off the  "enable" switch.  Set the AZ for 64 and the El for 
192.  Remember this value is NOT degrees, but the number of steps (0-255) 
from 0.

3. Measure the voltages at pins 4 and 18 of your D to A converter U1.  They 
should .25 and .75 volts respectively (If not the problem is between the 
computer and this chip).  Follow the voltage measurements out from U1 to the 
outputs of U2A and U2B they should match what is shown in the schematic 
(pin14 of U2 1.2 Volts pin8 of U2 3.7 Volts).  If not check the OpAmp U2 and 
surrounding cicuitry.

4.  If this is okay operate the controller (with the switches on the front) 
and move the antennas to AZ 270 and EL 135 degrees.  While moving the 
antennas manually you still should be able to see the voltages on the rotor 
connector move (pin1 (EL) and pin7 (AZ)).  When you reach your destination 
the voltages should agree with those measured earlier on U2. (If not check 
the connector wiring again and/or check to make sure the controller is 
outputting the voltages.

5.  If they agree go ahead and enable the FODTrack.  The antennas should not 
move more than a little.  If the antennas take off go ahead and turn the 
enable switch back off.  Manually move the antennas to where the voltages 
agree again and measure the outputs of the comparators pins 1,7,8, and 14 of 
U3.  All of these should read zero volts.  If not check the OpAmp U3 and 
surrounding cicuitry.

6.  After this, if the controller still takes off in an unexpected manner 
when enabled check out the transistors.  They could be bad, or it is easy to 
put them in backwards.  Any garden variety NPN will do the switching, but 
the BC546 in the schematic has a different pin out than a 2N2222.  In other 
words the transistor would have to be inserted backwards from the view on 
the parts overlay if a 2N2222 is used.  Just make sure the base of each 
transistor connects to the diode, the collector connects to controller, and 
the emitter connects to the "enable" switch.

Please let us know how it turns out, and/or if I can help further.

73 and Good Luck,

>From: "Bill Greene VE7WFG" <bgreene@telus.net>
>To: <amsat-bb@AMSAT.Org>
>Subject: [amsat-bb] Fodtrack
>Date: Sat, 14 Sep 2002 22:43:00 -0700
>Hello Everyone,
>I built up a Fodtrack Rotor controller today and it is doing weird
>things with my Yaesu G5600B's.
>When I turn the Fodtrack unit on ( there is an on off switch ) it
>immediately moves the antennas to 180ƒ ( both azimuth and elevation ) .
>I have set up the
>configuration file correctly I think ?
>Anyone have similar experiences ? Or am I just lucky hi hi ?
>Any info would be appreciated.
>I would like to thank everyone in advance for your responses.
>73 de VE7WFG
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

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