#firmware #i2c #smeter #ubitx #calibration #ubitx #firmware #smeter #calibration #i2c


George Metaxas (SV1DEQ)
 

Hello everyone, i am a new uBitx user, I have built uBitx v5 and loaded CEC firmware for Nextion 3.2 inch display. Moreover, I have incorporated a second Arduino Nano to use it as a standalone signal analyzer. I have gone through Ian's (KD8CEC) instructions to enable I2C S-meter and so on and what I see on the display is according to those instructions. The question is: Do I have to calibrate the I2C S-meter in some way, e.g. using a signal generator and applying -73 dBm (S9) to the antenna port of the uBitx? Has any of you done such a thing before?
73, George, SV1DEQ


Vic WA4THR
 

The CEC software allows calibrating the S-Meter through the Memory manager when using a simple amplifier circuit, and I did adjust mine until it generally agreed with another commercial receiver. However, when I changed to the second Nano and the standalone analyzer the readings presented seemed to be pretty close as programmed. I see in the program you could adjust values and recompile it, but given the limited resolution of the display it seems good enough as it is.

=Vic=


mymonte666@...
 

Is there a way to calibrate it without test equipment, other then a dvom. Like tuning to a stron station while hooked up on the bitx manager and setting the max, and then tuning to a blank station and setting the min? 

My s meter is doing s meter things, but i’m not sure if its accurate. It doesn’t go lower then s3 unless i’m changing frq’s. 


Vic WA4THR
 

Elecraft has (or used to have) a simple S-meter calibrator that put out a signal that was supposed to be S9 and was pretty inexpensive, if you really need to have accuracy. Then you could check it with another station adjusting their power remembering that each S-unit represents 4X the power (or double the voltage if you are measuring that). If it needs changing you will have to reprogram the second Nano. Having an S3 all the time is about right, that is typically the level of band noise. It should go to zero if the antenna is disconnected. As I said before, with the second Nano mine is agreeing pretty well with a commercial rig in the shack except for the timing as it is a bit slower to respond.

=Vic=