Signal strength meter - with audio output

signal strength meter A meter of this kind is very useful for determining the radiation characteristics of directional beam transceiver aerials. It allows the user to trim the aerial accurately for an optimum transmitting radiation pattern. An auxiliary aerial should be positioned a short way from the main transmitting one. The signal received by this is then fed to a resonance circuit formed by L1, L2 and the varicap C2. This enables the meter to be accurately tuned to the particular transmitting frequency to be measured. With the coil values shown in the circuit diagram the "band with audio output width" of the meter is between 82579 6 ... 60 MHz. The R F signal is then fed to the diode D1, which constitutes a rectifier/demodulation stage. Finally the signal is routed to the non- inverting input of opamp ICI. The gain of this opamp and therefore the sensitivity of the 1 mA meter is adjusted by P1. The prototype was found to be extremely sensitive, and highly selective. A pair of...