In this circuit, Ul is a frequency converter that feeds the 455-kHz IF stage U2 and detector
U3. U4 is the audio output stage. R9 is a gain control that varies the gain of U2. Coil data is given in the part list. R6, R710k, YiWcarbon composition R910kpotentiometer T1, T210.7 MHzmicrominiature (7mm)Mouser PN 42IF223 IF transformer, green core T3,T4455 kHzmicrominiature (7mm)Mouser PN 42IF203 IF transformer, black core U1, U3NE602double-balanced mixer U2MC3340variable attenuator U4LM380N-8audio amplifier U578L05100 mA miniature+5V regulator * C10 and C11 can range from 0.1 to 0.22. Valves greater than 0.33 cause distortion. Other: Printed stripboard, DSE PN H5614 or equivalent, cabinet, plastic stick-on feet, 4-40 hardware, etc.