Amateur radio operator points out that ``MagSafe charger interferes with certain frequencies''
An amateur radio operator reported that Apple's
Eliminating Radio Interference from Apple charger
https://oh8hub.substack.com/p/eliminating-radio-interference-from
When amateur radio operator Ossi Elara was touching the transceiver with a MagSafe charger nearby, he noticed that the scan stopped at 145MHz and there was terrible noise. It seems that the noise also occurred at the aviation frequency of 124MHz.
The frequency band where radio wave interference occurred is circled in red below.
According to Elara, MagSafe chargers operate on radio frequencies to generate magnetic fields, and when a high frequency of 105 to 205 kHz is forced into the MagSafe charger's coil, the coil emits a magnetic field, which causes the device to It is said that it will be captured and charged, turning it into electricity.
During this time, the MagSafe charger's cable begins to act like an antenna, radiating both the fundamental frequency and its harmonics. This interfered with Mr. Elara's radio.
As a countermeasure, Mr. Elara wrapped the cable around a ferrite core purchased for 2.21 euros (about 345 yen).
After wrapping it around for 3 turns, the spikes indicating interference went down.
This is a graph where the number of turns is N, the X axis is frequency, and the Y axis is resistance. If N = 2, it seems that a resistance of 1000 ohms could be obtained at 145MHz.
Mr. Elara said, ``If you trust the ferrite core manufacturer's specifications, two turns may be enough.However, even though you bought a product that cost 40 euros (about 6,200 yen), you have to repair it with parts that cost more than 2 euros. 'This is really a problem. I hope Apple can solve this problem more cheaply.'
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in Hardware, Posted by log1p_kr