A rf field indicator is required to verify power stages and transmitters antennas. With this radio field indicator you can measure radiated energy from antenna. This circuit is very sensitive, a weak signal is enough.
The S2 commutator allows to select : 480KHz … 2.4MHz / 2.4MHz … 12MHz / 12MHz … 40MHz.
A 30cm long wire is enough as a antenna.




RF indicator circuit schematic

radio field indicator fet schematic 260x300

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