3 Transistor - 4 IC AM Receiver

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This is a 3 transistor - 4 integrated circuit superheterodyne AM receiver. It covers the AM broadcast band from 530 to 1615 KHz. The receiver has the following features: separate oscillator and mixer for minimal spurious response, 2-IC IF (intermediate frequency) amp. for high sensitivity, 2 IF filters and 2 IFTs (intermediate frequency transformers) for high selectivity, AGC (automatic gain control) amp. for high dynamic range and a high gain IC (integrated circuit) audio amp. for monitoring the radio with a speaker. The active components are as follows: NE602AN (mixer), 2N2222A (oscillator), 2 x MC1350P (IF amps) and LM386N-1 (audio amp.). The receiver runs on a 9V battery.

Only 3 controls. From left: Volume, on-off and tuning. Phones jack is below the switch. A 6:1 reduction setup offers smooth and easy tuning. The receiver can be monitored with low impedance headphones or a speaker.


The upper board holds all the circuitry, antenna rod and controls. The lower board holds the 9 volt battery. The boards are attached together with threaded aluminum standoffs. Both boards are copper face down.


The circuit is connected to the battery (+) with a removable wire, allowing easy removal of the upper board for circuit modification. The battery (-) is soldered to the lower board and routed to the circuit through the aluminum standoffs.


The circuit was built "Manhattan style"; Small copper islands were glued to the board to connect and hold the components. Ground connections were soldered to the copper surface. The mixer and audio ICs are on the far left and right respectively. The oscillator coil with red core is on the lower left. The IF transformers are in proximity of the IF ICs. The 2 pink IF filters are on top. The tuning and volume controls are on the lower left and right respectively.


Bottom of lower board. 5 holes where made to allow adjustment of the oscillator coil, RF trimmer capacitor, the 2 IF transformers and the AGC level trimmer resistor. 4 self-sticking bumpers were attached to the board so the radio can be used on any surface.


Upper left: A potentiometer shaft and knob, dial string, tuning pulley and circular AM dial form the tuning mechanism for this radio. Upper right: Antenna coil was wound on a piece of business card and held in place with crazy glue. Lower left: The complete circuit and controls were successfully fitted on a 5" x 3" copper clad board. Lower right: Lower board with battery holder and aluminum standoffs. The battery can be easily replaced when the radio is assembled.


3-D view of the finished radio; small size with high performance. I usually enclose my radios in a plastic or aluminum box, but I decided to leave this radio "as is" to enjoy the fruits of my workmanship!


A short history | My radio background | Homemade radios | Tube radios
Transistor radios | World band radios | Kit radios | Reel tape recorders
My other interests | Pictures of Lebanon | Radio links
Home | Showcase | About this site

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