I guess driven by a BLDC motor.Found the problem, it was from the new aftermarket Vellman fan I installed in this unit.
Thanks, how can I know what motor type if I want to buy a correct one?Bad power supply would give 100 Hz rather than 50 Hz side band spacing. Also the modulation is apparently not exactly 50 Hz. Did you check with a marker?
I guess driven by a BLDC motor.
A series choke can help. But are you sure that the problem is electrical noise? It can be rotating magnetical field as well.
Modern DC fans have always BLDC drives. They are generating a lot of electrical noise and magnetical disturbances, too. I remember a case where a 2,5" HDD drive mounted near to a DC fan lost most of it's data throughput when the fan was running, apparently caused by magnetical disturbances. The problem could be fixed by a magnetic shield.
the YIG
Hi,
My mains frequency is 50 hz, do I suspect power supply caps ?
Thanks
BLDC fans unless exactly 1500 or 3000 RPM will not be your 50 Hz problem.
It will be either radiated from poor shielding or ground connections or conducted from poor filtering such as aged ESR in large electrolytics. Consider replacing all with high quality caps with low ESR, high temp types for supply filters.
Only you can tell by changing the method of grounding or isolation from magnetic lines of fields of 60Hz
If it were Caps , I would expect 100 Hz not 50, as all diode bridges multiply the frequency plus harmonics.
hint... So look for poor conducted or radiated grounds or power cables. A line filter is a good add-on if there are radiated or conducted noise. Or lack of common ground in measurements or poor shielding....
This still is surprising as modern DDS and PLL based generators have or should have enough PLL loop bandwidth to avoid/correct this problem.
Two way radios with PLL and build-in loudspeakers have long solved this problem and a fan should be much less complicated. If it is conducted rather then radiated interference then it seems a filter problem.
This still is surprising as modern DDS and PLL based generators have or should have enough PLL loop bandwidth to avoid/correct this problem.
Two way radios with PLL and build-in loudspeakers have long solved this problem and a fan should be much less complicated. If it is conducted rather then radiated interference then it seems a filter problem.
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