Tube radio with 4 tubes, experimental, schematic comes later.

Schematic of the 4 tube radio, experimentally built in a way of the radio-pioneers (1910-1945). The radio acts as a cascade type receiver when the antenna coil has a high self-inductance, with lower self-inductances of the antenna coil you can put in a mixing process with the oscillator. Perhaps...

Experimental receiver for VLF. I received electromagnetic (radio) signals between 14 and 22 KHz with a capacitor of 4,7 NF over the showed coil. The schematic is identical to that of the storm detector IV (with the 6088 Tube), the coil is differently constructed. There is one more transistor...