I also don't know if the 20 meter receiver spurs are unique to units with the AGC option installed as the AGC board sits right next to the micro-controller, and I should note that all 3 of my QCX-minis have the Rev 3 PCB.? The 20 meter spurs are present with and without the AGC enabled.
It would be interesting to hear if someone has a Rev 3 PCB version of the QCX-mini without the AGC board installed and whether they hear the 20 meter spurs or not.? It would also be interesting to see if someone has the Rev 3 PCB version of the QCX-mini without the TCXO board installed and whether they hear the 20 meter spurs or not.??
Don (wd8dsb)
