I thought I would mention this as it could be helpful to someone.
In another thread there was the mention that inserting an SSM2167 mic compressor circuit between the microphone and the uBitx mic-preamp would create some feedback when the microphone was placed near the speaker while in Rx.
The solution I applied was to connect the shutdown pin of the SSM2167 (pin 3) to the Raduino T/R digital output (D7) through a 47KOhms resistor. This disables the chip while in RX and removed the mic feedback issue.
Thanks Simon, VK3ELH for pointing out that issue.
73, John (VK2ETA)
Picture below of where I picked up the pin 3 on the SSM2167 on my module. The purple wire is connected to what is the right hand side of the R4 resistor on my picture. The 4.7KOhms resistor on the RHS is for the mic-bias and the 51KOhms on the top-left is for bringing the compression ratio towards 4.