US Digital's MA3-P12 is shown bottom left connected to the AZ/EL unit
Using the MA3-P12 from US-Digital
The MA3-P12 from US-Digital is available for about AUS$35. This small 'potentiometer look alike' device uses a AS5045 or similar device to produce a PWM output.
The device interfaces directly to an AZ/EL board but uses the new program for the 16F628A called PWMunit.hex
Preferred alternative to the AS5040/45 home brew is the US-Digital MA3-P12 absolute magnetic encoder
US Digital's MA3-P12 is shown bottom left connected to the AZ/EL unit
This is a very economical rotary encoder with an accuracy of better than +/-0.5 degrees. The device outputs PWM and I now have the hex code for a 16F628 or 16F648A working in the AZ/EL unit. The US Digital encoder connects to pins 1 (+5V), 2 (earth), 4 (PWM in) of the encoder connector on the AZ/EL unit. I have produced a separate manual to go with the source code describing how to hook it up. This is an ideal solution for satellite users and EME enthusiasts with beamwidths of the order of a degree. I have reprogrammed the switches as follows: SW1 180 degree shift in readout, SW2 if on sends ASCII to a terminal unit rather than the shack unit, SW3 reverse direction. Here is the hex code for the AZ/EL unit's PIC16F628/A or 16F648A. It accesses the pulse width modulated output of US Digital's MA3-P12. Here is the manual to describe how to get it going. I suspect the active unit inside the MA3-12P is an AS5045.
I recommend that if you buy one of these units that you also buy the plugs prewired. They are very tiny and not what I call fun to connect.
An encoder mounted in the top of a Ham 11 rotator
(the wire wound pot is removed)
The AZEL unit mounted in the baase.
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