I have a brand new 3206 and I am in general extremely happy with it. I am a bit confused by some results I am seeing though. With both inputs shorted using the spectrum analyser in average mode to check out the units noise floor I get the following results (in dBV):
Range A B
0.1V -89.9 -92.6
0.2V -89.1 -89.1
0.5V -81.7 -81.7
1V -75.7 -75.7
2V -63.7 -67.5
5V -61.1 -62.6
10V -55.6 -56.7
As you can see the two channels perform similarly except for in the +-100mV and +- 2V range where channel B is significantly quieter than channel A.
I have also found a spike in channel B at 84kHz - what is this? (picture attached - range is +- cV on both channels). This picture also shows the difference in noise floors quite nicely.
If I look at the scope mode rather than the spectrum analyzer I see that both channels (especially channel A) are MUCH noisier on +-2V than they are on +-1V or +-5V. On +- 1 and +-5 I get 1 bit of noise. On +-2 I get 4 bits of noise. Can this be fixed?