A Simple RF Radiation Detector

Here’s a quick and easy project to satisfy the FCC’s new RF radiation exposure rules1 while operating QRP.

PAUL SIGNORELLI

You can get a simple RF radiation detector right in the greeting card section of your favorite supermarket. The electronics inside those “musical” greeting cards (Photo A) are poorly shielded. When a card detects RF, it starts playing music and the LEDs start flashing. It can be initiated with a small handie-talkie. If you put your HT on some unused frequency (don’t use 146.52, 446.000 MHz or any repeater frequencies) and key the transmitter, you will find the card most sensitive to your frequency. My “dancing dog” card is most sensitive at 440 MHz and above (Photo B). I even used it to check the door leakage on my microwave oven (don’t put it inside). After calibration, all you have to do is hang the card around your neck while…

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CQ Amateur Radio (Digital) - 1 Issue, August 2022

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