Interesting: It says I am not being paranoid, by putting the blighters in a situation of containment.

Marc

Well, Ausgrid put their line monitor on the mains today but it didn't show anything out of the ordinary up to 5kHz which is the monitor's upper limit. This tends to indicate that what I am hearing is modulated on a high frequency carrier, and is being radiated more than conducted.

Am going to try to setup an onsite meeting with the VFD's supplier's support engineer next week.

It looks a lot like a spectrum analyser would be more useful.

Marc

Following a chance discussion today, I may be in possession of an HP spectrum analyser next week.

Hey I couldnt believe this. I was enjoying having a listen to my AWA Champion 4 this morning and all of a sudden it went louder with a little distortion. I went to adjust the tuning and it began to howl like a cat having a fight. I went to the next room and found that my wife had plugged in a el cheapo tablet charger. On switching it off all went back to normal. omg such a small device causing that sort of interference. she swapped to a Samsung branded charger and no problems hey.

...such a small device causing that sort of interference.

In his day, Marconi would have considered those things great miniature radio transmitters.

The absolute joke is that these days manufacturers assign themselves standards approval. The bureaucrats have all but given up managing this, although they continue to attend the office and collect their pay.

It can sometimes be a case of getting what one pays for. The less costly something is usually translates into less engineering. That said, I doubt there is a way to completely filter interference from a switchmode power supply. By their nature they ooze interference and they contribute greatly to earth leakage too. At a school I once worked at the classrooms had HP computers along the back walls. If around ten of them happened to be on one circuit they'd trip the RCD because the total leakage current was greater than 30mA. It became policy to split the existing circuits for computers and ensure that no more than six were on one circuit from then on.

HP isn't known for making junk so one can only imagine what the no-name products are blasting us with and most people won't notice it because most families won't have that number of computers running in one household. The high-rating AM radio stations are more likely listened to by people in their cars or by older folk who aren't running their computer at the same time.

I have a computer which completely wipes out AM reception for 100m in all directions. The problem seems to be in the power supply. Fortunately nobody has noticed (at least that I know of). I'm not planning on doing anything about it, as this particular computer is only used for a few hours one day a week.

I've also noticed that those touch-sensitive bedside lamps cause lots of hash, as do certain phone chargers.