I built a CW receiver using NE602 for the 20m band. Unfortunately, I do not receive any CW or SSB signals, only some noise and sometimes broadcast stations.
The schematic here shows the circuit that I built. What is wrong in the oscillator and input stages of ic that can not focused on 14 - 14.35 mhz (20m amateur band)
In oscillator section as you see i used two 220pf capacitor that are in series with each other so the total capacitance is equal to 110pf . For resonance at 14 mhz with present inductor (1uH) we need a capacitor value 129pf using formulae: (C=1/39.5 * F^2 * L) so if the varactor diode can induce about 19pf , the work is done (110+19=129) the second image show the internal transistor of ne602 chip and relationship between pins 6 and 7 and the other parts of oscillator section (https://i.stack.imgur.com/e1HLp.jpg)