All Potentiometers used by Yaesu (and other manufacturer) use 3 wires; something similar to the following image: Note: this POT is only used to illustrate the guide. Yaesu controller will supply an Input Voltage at pin#1 meanwhile will connect pin #3 to ground. Then the controller will read the voltage feedback at pin #2. As the POT axis is connected with the rotor axis, when the rotor moves from Left/CCW limit to the Right/CW limit, the output will be a value from “Input V” to “Zero” Volts. When you are going to replace the original controller by the ARS-USB device, you must do a similar wiring and in our case we can choose the Input Voltage as 5Vdc or 13Vdc (any of them will work property). The wiring of the POT will be:

  • Pin #1: this is the pin of the POT that must be powered. You can use 5Vdc or 13Vdc.
  • Pin #2: this pin will provide the feedback voltage and it’s used by the ARS-USB as position reference. If you use 5Vdc (pin #1) it will provide from 0V to 5V when you move the rotor from one left limit (CCW) to right limit (CW). This pin will be connected into J4-5 @ ARS-USB PCB.
  • Pin #3: ground. This is the ground reference for the POT and must be connected “J4-3 & J4-4” (both terminals must be connected) and the power supply ground.

Now there are some verifications you must do first. A.- Linearity voltage feedback @ POT: Power on the ARS-USB. You must also power the POT (pin #1 and pin #3) so in this guide we are going to suppose you use the same Power Supply (13Vdc) used to power the ARS-USB device. Move the rotor from Left (CCW) limit to Right (CW) limit and check that the voltage feedback at #2 is proportional and linear to the movement applied. If you notice there is some problem at this point, verify again and you must ensure that the POT is working property.

B.- Adjustment CW and CCW Limits:

As the ARS-USB works as a voltmeter, it needs to know the voltage supplied by the POT at both limits.

So first move or turn the rotor to the Right (CW) limit. If you have used a 13V Power Supply @ Pin 1, you will measure the feedback voltage @ pin#2 = 12Vdc

As the microcontroller supports a max. voltage of 5V adjust POT1 (blue color) until you get 5V at the point marked in the following image:

Instead a voltmeter, it’s highly suggested to use the ARSConf program. The ARSConf (included with the ARSVCOM program) will help to calibrate the unit and surely it’s the best option because will allow you to enter all parameters required to the ARS-USB for a correct setup. Also it will save thosae values internally at the ARS-USB equipment.

So visit this link where it’s described how to calibrate the ARS-USB:

https://ea4tx.com/en/faqs/arsvcom-faqs/arsvcom-calibration-error/

Once you have adjusted the trimmer and you read an ADC value in the 1020-1022 range then you must capture this voltage or ADC value, so the ARS-USB will use and save this value as the Right/CW limit. 

Later, move the rotor to the Left/CCW Limit and simple capture the CCW Limit. It will display a value as 000 or a low value. 

Note: Don’t adjust the trimmer, just only press over the “CCW” button on the ARSConf.

Finally indicate the Total rotation you want to use, for instance 360º (default value) and the Left limit position (000º or 180º). Yaesu uses 000 as default left limit.