Hello gents, I have an WBX board with faillures. I repaired most of the damage ( done by another ). The only strange issue is that on the WBX_fe board there is an U6, in the schematics refered to as an MGA6x563. This is under the assumption that this is an MGA62563 low noise hemt pre-amp with bias. However, my board has the bias pin tied the pin down to ground. In other words, there is no bias. I replaced the broken U6 ( whatever type it is ) by an mga62563 and end up with negative gain. ( since there is no bias pin on the board ). The SMD marking on the original chip was 62F and not 62x. The schematic on: http://files.ettus.com/schematics/wbx/wbx_fe.pdf says clearly that there must be a bias pin on the board. On my board there is no bias pin ( directly grounded ). Also, there is no bias resistor R68 on the board as well. According to the datasheet of the MGA62563 the device will directly die with 0V bias. Ofcourse there is vcc 3.3 volt on the supply pins. Anyone a clue which chip this should be? Br Evert Verduin

Hi Evert, Could you tell us which hardware revision this is? I think you're right, this should be an MGA62563, but I'd have to check. Best regards, Marcus Am 19. April 2017 11:43:23 MESZ schrieb Evert via USRP-users <usrp-users@lists.ettus.com>: >Hello gents, > >I have an WBX board with faillures. I repaired most of the damage ( >done >by another ). > >The only strange issue is that on the WBX_fe board there is an U6, in >the schematics refered to as an MGA6x563. > >This is under the assumption that this is an MGA62563 low noise hemt >pre-amp with bias. > >However, my board has the bias pin tied the pin down to ground. In >other >words, there is no bias. > >I replaced the broken U6 ( whatever type it is ) by an mga62563 and end > >up with negative gain. ( since there is no bias pin on the board ). > >The SMD marking on the original chip was 62F and not 62x. > > >The schematic on: > >http://files.ettus.com/schematics/wbx/wbx_fe.pdf > >says clearly that there must be a bias pin on the board. On my board >there is no bias pin ( directly grounded ). >Also, there is no bias resistor R68 on the board as well. >According to the datasheet of the MGA62563 the device will directly die > >with 0V bias. > > >Ofcourse there is vcc 3.3 volt on the supply pins. > > >Anyone a clue which chip this should be? > > >Br > >Evert Verduin > >_______________________________________________ >USRP-users mailing list >USRP-users@lists.ettus.com >http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com -- Sent from my Android device with K-9 Mail. Please excuse my brevity.