So I just purchased a etherwave kit, built and, and it doesn’t work. So I realized two of the components on the circuit board were touching, and I fixed that, but pretty much all it’s good for now is a radio where I can control the volume with my hand (the volume antenna works), but I can’t seem to make any changes by moving my hand closer or further away from the pitch antenna. What should I do?
a) At first make sure that the wire between the circuit board and the pitch antenna does not touch the aluminum foil. Make also sure that the theremin is in a free space (i.e. on a mic stand) in the room with no other metallic or electric equipment inside a virtual sphere with 2 meters (6 feet) of diameter around the pitch antenna.
b) Then connect a frequency counter via a 1:10 oscilloscope probe on the pin of L12 which is connected to L5. Pull the probe cable straight towards the left side of the circuit board in order to avoid adding parasitic capacitance to the pitch circuit. Move your body more than 70 cm (2.5 feet) away from the pitch antenna. Set the pitch knob to its center position. Switch the theremin on. Check if the frequency counter shows now a frequency between 290 and 289 kHz. If not, adjust L5 until it does so. Then approach your hand to the pitch antenna. The frequency should now go down to ca. 286 - 285 kHz when you touch the pitch antenna. If it does not or almost not vary, continue with step c) else step d)
c) Switch the theremin off and check the connection between pitch antenna and the circuit board with a multimeter. Then check the three coils on the right side of the circuit board if their DC resistance is about 24 Ohms. If one of the readings is much greater, the coil is defective (happens sometimes) and must be replaced. Then check the overall resistance between pitch antenna and the pin of L12 which is nearer to the front panel. DC resistance should be below 80 ohms. Now you are sure that the antenna may interact correctly with the pitch oscillator. Switch the theremin on and check back on step b).
d) Connect the frequency counter to the pin of L13 which is connected to L6. Adjust L6 to read an identical frequency as the first reading (somewhere 289 to 290 kHz range)in step b). Now you should hear a frequency which increases when you approach the pitch antenna.
e) Now optimize the tuning (when placing the cover on the theremin, the variable pitch oscillators frequency will go somewhat down due to the 9 big metal screws in the cover): Disconnect and remove the frequency counter. If L6 has a hex slot, adjust it somewhat counterclockwise, else clockwise so that you hear a high tone when you are far away from the pitch antenna which goes down when you approach your hand to the pitch antenna, reaches “zero beat” at a distance of 10 cm (4") and goes up when you come still nearer. When this setting is obtained, close and screw the cover, you are done.