Roberto,
The results of the IC5 test would indicate that it is OK.? IC5 is most likely not the issue.
I suggest that you verify that the LPF diodes are correctly selecting the LPF and that the BPF selector (IC3) selects the correct capacitor.? I check the BPF selector by measuring the voltage on the selected filter capacitor.? It should read 2.5 volts.? The other 3 should read close to zero.
With a dual trace 200kHz scope, you should be able to check the inputs to the +VinL and +VinR of IC10 (the 24-bit ADC).? These should be 90 degrees out of sync with each other.
There is a diagnostic page on the QRP-Labs website:
73
Evan
AC9TU
