3 Transistor-6 IC SW Receiver

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The drifting analog VFO is history!

This is a 3 transistor-6 IC dual-conversion superheterodyne receiver with continuous coverage of the SW bands from 5.7 to 22 MHz. It has a DDS VFO (Direct Digital Synthesis Variable Frequency Oscillator) and a back-lit LCD frequency display for accurate and drift-free tuning. It copies AM broadcasts and provides IF (Intermediate Frequency) output for copying SSB (Single Sideband) Radio Amateur signals with my homemade SSB Monitors. The receiver has the following features: an IC (Integrated Circuit) RF amplifier for good sensitivity with a short wire antenna, 2 Gilbert-cell balanced mixers for clean signal conversion, 2 IF amplifiers with AGC (Automatic Gain Control) for good strong signal handling, 2 ceramic IF filters for good adjacent channel selectivity, a back-lit LCD frequency display, and a signal LED to show relative signal strength. The receiver runs on 12 volts DC and performance is on par with high quality commercial SW receivers.

Receiver schematic


Dimensions: 10"(L) X 5"(W) X 3"(H). Controls from left: Top row: Volume, Display Contrast, LCD Display, RF Tune, and RF Gain. Bottom row: SSB Monitor, Memory Call, Tuning, Memory Down, Memory Up, Antenna Off and Power On/Off. The 3 Memory push-buttons are used to adjust functions of the DDS VFO such as IF shift and tuning step. Antenna Off push-button disconnects the antenna so I can peak the RF tuner by ear for maximum static. The SSB Monitor switch allows the receiver to copy Radio Amateur signals with my homemade SSB Monitors and activates slow AGC inside the receiver. Audio jack and signal strenght LED are below Volume and contrast controls respectively.



Receiver back. Ground and Antenna wires connect to the black and red spring terminals respectively. 12 volts DC supply connects to the red RCA jack on far right. 3-pin jack channels IF signals to my homemade SSB Monitors so I can listen to HAM (Radio Amateur) communications.



Inside the receiver. Circuitry was built Manhattan style on 3 copper boards. Copper surface was used as a common ground to improve overall stability. All ICs (Integrated Circuits) plug into IC sockets. DDS VFO is green board at center. RF tuning capacitor can be seen bottom left. Two white resistors in parallel (bottom right) supply the right voltage to display light. A miniature relay on a small board (upper right) activates slow AGC when SSB Monitor switch is on. LCD display is attached to receiver box with aluminum standoffs and modified terminal strips.


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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