GM0ONX's Radio Artisans Arduino Rotator Controller

My ZL1BPU rotator controller served me well for many years, but it was not without its problems. The controller did not have an integrated digital display and

relied on a voltmeter circuit to display  the heading which did  not always align the computer display. The Yaesu emulation was poor being unidirectional and

ZL1BPU own commands only supported by PSTrotator.


I came across  this project  on Goody  K3NG's Radio Artisans website and  though this would  make an excellent alternative way to do things. Clone Arduino

Uno boards  are available on  eBay for less than  a fiver with the  20 by 4 line  costing  about  the same.  The  project  'sketch' is well documented which is a

good thing because they are a few elephant traps in it for the uninitiated and I must have found them all.


The only other  non standard   thing compared to K3NG's original  is in my controller  the relays  are the are active low,  that is they  close when  the circuit is

grounded  and were   purchased from eBay complete  with  the PCB circuit in place.  These  are very handy little unit s and a steal  at less that 3 for the set.

The project is completed  with 99p encoder switch also  from eBay. You can find my version of the sketch which is set up for 'ground to operate' relay boards,

20*4 display by clicking here. You will need one of the older Arduino IDE to load this sketch and you can find them here . I believe I used version 1.0.5.


Remember  you will have   to calibrate  the rotator this is done via the Arduino IDE program and  is very simple. Rotate  the rotator fully CWW  and  then from

the command  line send the letter '0'  then return. Send  the rotator fully CW and  then send the letter 'F' and  then return. The  interface is  compliant with the

most common Yaesu GS232 commands and you can find more info on this on page 16 of the GS232B Manual found here.





The Ham IV  rotator  however has  a major  Achilles Heel in  its design, it  shares  the return  path with  the  rotator motor  and  brake which has a 0.5V ripple

voltage  on it causing 'interference'  on  the  rotator  position  sense voltage. I  originally  modified  the variable  resistor in the Ham IV so  that  the wiper was

isolated from earth and ran a separate to the wiper arm, but after a few weeks the isolation wore through and made connection with earth again.


Following a  conversation with Barry Beggs  GM3YEH he suggested  that I  build a filter to remove the ripple voltage and this worked very well. Because the

wiper  arm  is connected  to earth  I  had to  provide a  separate power supply  just for  the sense voltage in which neither  the positive or negative lines are

connected to earth.  





Now in its third guise the GM0ONX Ham IV controller


 Plenty of space left for a speed controller board for slow starts and stops  if required.



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