Product detectors are used to detect Morse (CW) and single sideband (SSB) signals by mixing those signal with the output of a local oscillator. The resulting audio will be at a relatively low level and will require filtering and amplification before it can be heard.
1. Active Detector
This circuit has sufficient gain to be used as either a product detector or a direct conversion receiver (DC Rx). The first set of notes apply to both applications, the second only to a DC Rx.
DC Receiver Notes: