BFO

One of the most common circuits used for (BFO) is shown below. The signal of the BFO fed to the Pin Diode Switch and used from  the Receiver and Transceiver units. The C45 and IF2 with C47 are used to adjust the USB and LSB frequencies. When we bias  the USB or LSB input with 5 volt, we choose which mode we want to apply.

BFO Circuit