NBFM-5

The NBFM-5 has an input of 10.7MHz felt at Pin 4 which is sent through the U1 stage. The Q1 stage produces a frequency of 10.245MHz thanks to a crystal rectifier which is then sent to the U2 stage. The U2 IC Chip will subtract the difference of the 2 inputs and produce an output of 455kHz. 10.7-10.245=455 This signal is sent to the U3 stage for amplification before going to Pin10 and the SLM stage where the frequency is converted to .1 Pulsating Volts DC or greater, at the output on Pin 12.