I have Don's & Kees' AGC board in my uBitX and am trying to get the S meter function in Ian's firmware working. I've been using the S meter helper in the Manager to try to set some meaningful values but have not been terribly successful so far. It seems like only the strongest signals give a usable level, it shows either a very small value or about a 75 value with little variation in between, it's either S1 or S9+ with nothing in between.
I borrowed an Elecraft XG2 receiver test oscillator from a friend to try the calibration with known input levels (it puts out 1uV and 50uV signals on 80, 40, and 20M). Measuring the voltage on the AGC board at J1 I get the following (I hope this is readable):
Band No Sig 1uV 50uV
80 .4mV 1mV 1.6V
40 .3mV .5mV 1.7V
20 .3mV .7mV 1.6V
Are these values typical? I'm not 100% sure the board is working correctly anyway...it's my first attempt at surface mount assembly so I may have messed up something altho I don't see any obvious problems. The radio seems to work just fine otherwise and the receiver seems to have decent sensitivity, to my ear at least.
The S meter is certainly not essential but since it's there, I'd like to see if I can get it working.
Anyway, any advice/opinions/comments are appreciated.
Mark AA7TA
