µBITX-V6 kit-prjects AGC module Smeter voltage is too low #ubitx #smeter #v6


The output signal "S" for use as "S-meter" is honestly too low:
the variation goes only from 0.2/0.5 mV to a maximum of 1.8 / 1.9 V with an antenna input of S 9+30dB (-43dBm in antenna), this severely limits the possibility of use through the A7 input without changing the ATmega328 Vref reference value.

The ATmega328 have only two Vref values : 5V (DEFAULT) or 1.1V.

To use the original V6.3.1 software, which uses several analog inputs for some functions, it is necessary to switch the Vref every time that reads the value of the Smeter and put it back in DEFAULT to continue the control loop of the rig.

I would like to know if the voltage value read on pin S of the kit-projects AGC module is correct or is there some way to have higher output levels?

Thank you all !

greetings ... 73 de IW4AJR Loris



I use a board with ADS1115. Also, I feed the LM386 with 12v.
This offers a more reliable reading than pin A7 on the Arduino Nano and widens the voltage range at the output.
On the other hand, you have 3 other channels to read the Vfor and Vref values ​​and measure the SWR.
You need to modify the firmware, of course.