After acquiring a National vernier dial and a few plug-in coils, I decided to build an old fashioned regenerative SW receiver. The result was this hybrid 2 tube - 2 transistor set, which looks like the homemade receivers of the late 1930's. The set uses 4 plug-in coils to cover 1.5 to 18.7 MHz. The front end uses an FET (field effect transistor) RF (radio frequency) amplifier, coupled to a second RF tube amplifier for good sensitivity with a short wire antenna. The regenerative detector is followed by an FET AF (audio frequency) amplifier, coupled to an AF tube power amplifier capable of driving a speaker. Performance and selectivity are good, and tuning with the National vernier dial is smooth and accurate. The receiver runs on 110 VAC.

Controls from left: main and fine tuning (top), volume, regeneration and antenna gain (bottom). On-off switch is part of the volume control, and red power-on light is in top left corner. The receiver can be monitored with a speaker or low impedance phones.

Power for the tubes and transistors is obtained directly from the mains (no transformers). Half wave rectifier tube (right) supplies DC voltage to the circuit. Detector tube (center) was shielded to reduce hum. Plug-in coils (left) are easily changed to switch bands. Compression terminal blocks are used to connect antenna & ground (left) and power cord (right).

There was plenty of space for point-to-point wiring. Power supply filter capacitors are on far left. Transistors (in sockets) and appropriate components were wired on small perfo-boards and connected to the circuit. Regeneration capacitor is between volume (left) and antenna (right) controls on top.