Crystal - Tube Radio

This Crystal - 1G4GT tube (50 mA on filament), or HY-113, or about any 1.4 volt filament (shown as lamp) bantam triode type tube with 75 to 100 foot long antenna and a good cold water pipe ground does well on local and long distance stations. All resistors are 1/4 watt rating. Left antenna coil (shown as 1 nH) is 20 turns of #30 enameled wire. Coil to right is 90 to 120 turns of #30 enameled wire (add or remove coils to cover broadcast band, or a larger adjustable capacitor where the 14 pf fixed capacitor is located). Wind turns of both coils in same direction. a 150 nf fixed capacitor in parallel with adjustable 14 pf capacitor will help on the lower frequencies. The 20 K ohm resistor on right is where the headphones plug in. Try reversing the 1N34 or crystal you are using to see if you get better sensitivity.

published 9 years ago