General Coverage Short Wave Receiver - 0.5 to 30 MHz
This was my attempt to build a general coverage short-wave radio covering 500 kHz to 30 Mhz, using a DDS (Direct Digital Synthesis - from minikits in Australia) VFO with 45 MHz local oscillator. This technique is typical of modern high performance receivers. The emphasis is on minimul controls, and the RF circuitry is untuned. The block diagram is shown below:
Performance is okay, but not as good as I would like. The AGC and audio circuitry needs attention, and I did experience some FM breakthrough (though I think that proper screening has cleared this up). The breakthrough was bypassing the 32 MHz LPF on the antenna. I have been doing other things, but hope to get back to do more work on this someday. The Noise Blanker has not yet been built.
Click on the circuit diagrams below to display full size image.
© In the Light, 18 March, 2011 , Disclaimer, Son of Suckerfish drop-downs from HTML dog