Operating an old "null" distortion analyser wasn't hard, just time-consuming if you wanted to measure distortion at many frequencies. Modern FFT analysis shows nearly all distortion at a single glance.
Walters,
You are asking questions about harmonic distortion without knowing anything about it. Try Google first before asking basic questions here.
You don't null harmonics, they are the distortion. You null the fundamental frequency.
An AC meter or 'scope showed the level of the harmonic distortion as a percentage of the level of the fundamental.
They sure are simple basic questions. They show that you know nothing about distortion and a distortion analyser.
They show that you haven't bothered looking for the answers yourself.
You seem to be just reading the index or just looking at the pictures in a textbook without reading its articles. :cry:
Walters,
In Google I entered How To Measure Harmonic Distortion and links on the 1st page answered all your questions. Some are confusing so maybe a textbook is best.
2nd harmonic distortion is called even-harmonics distortion and usually includes all the other even-numbered harmonics in the total of its distortion. It is caused by a non-linear device passing a positive or negative part of a waveform more or less than the other, like a rectifier.
A Jimmy Hendricks "fuzz-face" circuit produces severe 2nd (and others) harmonic distortion.
An ordinary transistor without negative feedback produces 2nd (and others) harmonic distortion:
"2nd harmonic distortion is called even-harmonics distortion and usually includes all the other even-numbered harmonics in the total of its distortion."
Is 2nd harmonic distortion comes from the silicon transitor or germanium transistor?
What causes the 2nd harmonic distortion?
I thought Tubes produced odd harmonics not even so tubes don't have 2nd harmonic distortion?
"It is caused by a non-linear device passing a positive or negative part of a waveform more or less than the other, like a rectifier"
This part i don't understand passing a positive or negative part of a wavefrom?
A rectifier has 2nd harmonic distortion?
A Jimmy Hendricks "fuzz-face" circuit produces severe 2nd (and others) harmonic distortion.
How and Why?
Why does negative feedback produce 2nd harmonic distortion?
No. Any class-B transistor or vacuum tube circuit without negative feedback causes odd harmonics distortion. An amplifier that clips symmetrically produces odd harmonics distortion.
If the upper half of a waveform is amplified or reduced more or less than the lower half, then there is even-harmonics distortion because a transistor or vacuum tube is non-linear without negative feedback.
It passes only the upper or only the lower half of a waveform. Even harmonics are produced when the amplification or loss of the upper half and the lower half are different, caused by non-linearity.
Because it doesn't have negative feedback and it is improperly biased.
Here is a sim of it playing a pure sine-wave. Notice how the lower part of the sine-wave is removed, like a rectifier: