Software Defined Radio receivers used at http://hf.pi5fts.nl for WebSDR
HF bandpass filter
HF band filter for 1,8 MHz (160m)
HF Ampifier10 kHz to 70 MHz with BFW16A
USB programmable oscillator with a SI-570
A basic SDR receiver system conncted to a soundcard needs only an
SDR converter and the SI-570 programmable oscillator.