"When it was brand new, i've measured the frequency at ~35KHz,
modulated by 100Hz (double rectification of the mains' frequency. "

So they don't bother filtering, like a microwave. Hmmm.


** Microwave ovens have similar line frequency modulation and for the same
reason.

The high voltage PSU is not filtered.

Electronic transformers for 12v halogen lighting are the same too.


.... Phil