Through a variety of experiments with nodes of coherent reception of radio is very convenient to use a low frequency amplifier with enhanced functionality. In receiving SSB signals requires a low-pass filter (LPF) with adjustable cut-off frequency (to suppress the "tails" from neighboring frequency radios), and for the reception of CW signals is very useful low-frequency bandpass filter (LBPF) at the frequency that provides the most comfortable tone for the operator (typically 650-750Hz, although some hams prefer the tone lower, for example, 500 and even 300 Hz, and others higher, e.g., 900 Hz). Skipping the CW signal through the cascaded LPF and LBPF, it is possible to significantly improve the selectivity of reception.
At the circuit's input signal with the linear output of Receiver. The input level can be in the range of 10 to 200 mV.
KIT: all components required for assembly. PCB 64*46mm