You're close, but no cigar.
Refer to my post (#20).
When your generator is calibrated at the "0" mark on the meter and you have all attenuation out, according to the manual for your generator, you have 100,000 microvolts.
0 dbm is 223,000 microvolts.
Your generator is already -7db below the standard of 1 mw into 50 ohms = 0dbm.
(square root of (50 ohms x 0.001 watts = 0.223)
You need only add 99 db of attenuation to establish -106 dbm.
Put all attenuators in. ( 20,20,20,20,10,6)
Then dial the meter down from "0" (the calibrate mark) to "-3".
The signal level required to get a certain S/N reading on the SINAD meter is going to vary from radio to radio (even with the same model number and even if they have consecutive serial numbers it will vary a bit)
Just use a signal level that is sufficient to allow the SINAD meter to function properly.
( I should note that the frequency accuracy of the 1kc tone is very imporatant so that if your results vary drastically from what is expected then the frequency of the 1kc tone should be investigated, if it is off by too much the SINAD meter will not work properly)
If it requires more signal level than the standard of 1uv then use more and make your alignment and if your alignment improves the sensitivity of the radio then turn down the signal level from the generator and touch up the alignments till you get the best S/N with the least amount of signal level from the generator.
If you end of with 0.3 uv for 20 S/N SINAD then you got a radio that will have great receive.
If you end up with 2 uv for 20 db S/N SINAD then you got a radio that will have a little less receive sensitivity.
Once you have aligned the radio for the best S/N according to the SINAD meter then turn down the generator and take note where the S/N drops below the standard level.
This will be the specification for that radio in your domain.
It may well be different if performed with different equipment.
Even with laboratory grade equipment there will be minor variances.
