This sophisticated remote field strength meter circuit was found in a 73 magazine for radio amateurs from the1990s. The circuit measures signals in the 1650 kHz range.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
This circuit can act as a shield being controlled by a microcontroller by pin 1 or 2. The...
This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals...