For the 7 to 10 MHz band L1 is formed by 3 turns of 22 to 28 AWG wire in a ferrite core 15 to 20 cm long and L2/L3 formed by 16 turns of the same wire. The RF choke is formed by 80 to 120 turns of 32 AWG wire on a 100k Ω x ½ resistor. The circuit needs a long external antenna and the output mist be applied to a amplifier. Equivalent to the MPF102 such as the BF245 can be used. Current drain is very low.
Regenerative Short Wave Receiver
