[Discuss-gnuradio] USRP2 with strange RX behavior (ADC damaged?)

[BENOIT Clément]

Hi everyone,
I've been playing with my USRP2 for a while and last week I noticed a strange behavior. The early signs were that my USRP2 was deaf so I tried to switch the daughter-board from a WBX to a LFRX and the problem seems to be identical.

- When one antenna is connected to RX, the scope is flat with a senseless fft => -400dB.
- When a -50dBm sine CW is sent to RX, ~=-80dBm (and plenty of harmonics) is readed by USRP2. Furthermore, the sine wave (on the scope) seems to be badly sampled in amplitude.

Looking around on the mailing list i found something about the USRP ADC fullscale and PGA :
"If you turn the programmable gain amplifier (PGA) down to 0 dB (the default),then a full-scale signal would be 2 V p-p.  If you turn the PGA up to +20dB gain, then full-scale would be .2V p-p"

-Is the USRP2 ADC fullscale/PGA works like USRP1? 

-If yes, is it possible to damage the USRP2 ADC if some signal is sent to it through a wrong PGA adjustment? 

Finally, if my USRP2 is damaged (I'm pretty sure the ADC is toasted) what is the way to repair?
Send it back ... but where? How do you usually do with damaged equipments?

Regards,
BENOIT-PILVEN Clément