Tag Archives: AM radio

Review: Grundig Mini400 AM/FM/SW Radio as ESD/EMI Detector

I recently upgraded my old Radio Shack AM radio, which I used for ESD detection, for the Grundig (Eton) Mini400 AM/FM/SW pocket radio. This $30 (street price) pocket-sized radio (4.25 x 2.75 x .5 inch) seems to have plenty of sensitivity to nearby ESD events. By tuning off-station, you can clearly hear the “clicking” from the ESD from several feet away. Using one of these radios is handy for correlating random product glitches with possible ESD events.

Grundig Mini400

I’m also finding it’s quite useful in locating low frequency switch mode power supply (SMPS) EMI. The shortwave bands are especially sensitive to this noise. For example, the CFL and newer LED lamps each have a SMPS built in to their bases. The multitude of these lamps in homes today can create a cacophony of EMI well above the shortwave spectrum. This is a real issue for amateur radio operators and those who enjoy radio astronomy.

The radio has an analog tuner with digital display. It runs on a pair of AAA cells and seems to have plenty of audio. It also comes with a padded case with belt loop. The only caution I might point out is that the power switch is a momentary button, which could get pressed inadvertently if pressed during shipping or if packed tightly in your troubleshooting kit. The radio does have a “Lock” switch on the side that disables the power button, so that ought to alleviate that issue. You just have to remember to unlock the radio prior to use.

Frequency ranges:

AM: 517 to 1782 kHz (1 kHz steps)

SW1: 5.700 to 10.380 (5 kHz steps)

SW2: 11.600 to 18.450 (5 kHz steps)

FM: 85.8 to 108.7 MHz (0.1 MHz steps)

I bought mine from Radio Shack for $40, but you can find one on Amazon.com for $30. Recommended.