The instrument of this field strength meter, from a 1970s publication, can be a 200 uA microammeter or a 1 mA milliammeter. The coil must be according to the monitored frequency and the variable capacitor can be obtained from an AM or FM radio out of use according to the tuned range. The diode can be 1N34. C1 is 330 pF and C2 and 1 nF, both ceramic. In J1 a telescopic antenna is connected.
