Dispelling the mysteries of radio. A series featuring a variety of practical circuits for the set builder and experimenter. This month: Tuning systems, coils, and coil packs for general coverage and the amateur bands.

In Part 3 of this series, the basic requirements of a regenerative receiver for serious listening on the long, medium and shortwave bands were listed and a simple but effective practical circuit described. This month, we explore the merits of tuning systems and give details of add-on coil packs to extend the coverage of last month’s High Performance Regenerative Radio into the amateur bands.