The CA3189 IC integrates a symmetrical limiter, a phase demodulator, an audio amplifier, and a logarithmic detector-amplifier. The logarithmic detector-amplifier is the most interesting part of the IC for the above featured circuit. It can be used to enhance the “logarithmic signal meter” of shortwave receivers to make the signal reading more accurate.
Building the circuit is very simple. It must be built in such a way that it will work up to 30 MHz. To do that, follow these guidelines: connect the input to a 50 Ω line; make the circuit wiring as short as possible; and the input signal must be shielded.