Measuring line noise and power conditioners

mijostyn

"All this stuff about power cords, conditioner and fancy outlets is nonsense."

Only this statement is.

RFI also known as EMI types,

Electromagnetic interference can be categorized as follows:

• narrowband EMI or RFI , which typically emanates from intended transmissions such as radio and TV stations or mobile phones
• broadband EMI or RFI , which is unintentional radiation from sources such as electric power transmission lines.

And, Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infraredfrequencies;[1][2] these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.

A minor correction to my previous post: In the first paragraph when I said:

"... when the instantaneous voltage of the incoming AC waveform exceeds the voltage on the storage capacitors by the small amount that is sufficient to turn on the rectifier diodes."

I should have said:

"... when the instantaneous voltage of the AC waveform at the output of the power transformer exceeds the voltage on the storage capacitors by the small amount that is sufficient to turn on the rectifier diodes."

That applies, btw, to both the positive and negative peaks of the AC, assuming (as is usually the case) that "full wave" rectification is being used

Regards,
-- Al

Conventional filters will do little in actual power lines or may even amplify EMI - it is in their own specification (that is, for those manufacturers who bother to publish such specification).  For a brief explanation please see this link:  https://www.onfilter.com/real-life-filtering    In short, regular filters are designed to perform at 50 Ohms termination (in and out) for EMC Compliance - CE and FCC.  I personally haven't met a power line with 50 Ohms impedance.  In real-life applications a better impedance ratio is 1/100 or 0.1/100 (not a critical difference in reality) where 1 or 0.1 is output impedance of AC power and 100 is rough number for a load, i.e. your amplifier.  It is imprecise but much more realistic than 50/50 Ohms. Since a filter is a combination of inductors and capacitors, when designed with one goal in mind to work in a 50/50 Ohms environment, this is where it "tuned" to.  In actual use it either does nothing or amplifies noise.  Our company (tooting my own horn here) designed filters for actual installations that we provide to the factories around the world, NASA, governments, hospitals, etc. - they are impedance-independent and essentially kill emissions anywhere they are plugged in -  https://www.onfilter.com/ac-power-line-emi-filters