Basic schematic Callisto

Callisto is a double heterodyne receiver with two IF, first at 37.7 MHz and 2nd at 10.7 MHz.
RF- and IF-gain are controlled by a PWM-signal via ATmega16. Detector is a logarithmic AD8307.
Tuner is Philips CD1316x, where x denotes to different versions.
Callisto is connected via RS232 (115 kbit 8N1) to a standard PC running on Windows 98, 2000, XP or 7. Third party software for Linux can be found on my instrument website.