With the presented circuit it is possible to detect signals from transmitters in a frequency range ranging from 100 kHz to 100 MHz. With it we can prove the operation of small and large transmitters. The antenna is telescopic 20 to 80 cm long and the trimpot must be adjusted to obtain a near zero current on the indicating instrument. The RF shock can be worked out by winding about 500 turns of thin wire on a ferrite rod 10 cm in length or less. The diode is germanium and admits equivalents.
