AC Power line harmonics
Below is the typical spectra of a 60Hz AC power line. In cases where more non linear loads are drawing on the system the harmonic distortion may be even worse. This explains why ML detector are still affected by power line nose even although they are not supposed to respond to any pure sinusoidal signals signals below their Tx frequency. While these harmonics are very much lower in amplitude than the fundamental they are are still very significant in high gain circuits and of course above the TX frequency are cumulative. But the real proof of the fact that ML detectors (even the 4500) are effected by power line noise is to try and use one with a big mono in the vicinity of power lines and see what happens. So don't believe all the nonsense of "experts" like Van T on flounders who on this subject is clearly and demonstrably wrong!These "experts" are merely trying to wriggle out of the fact that ML have still not come up with method that eliminates AC power line noise!
doug :)
But what does this mean to Pee Jo's predictions of harmonicas playing in the QED?
Do harmonicas play at such low frequencies (in low keys)? Does that mean you can't use an amplifier or a hearing aid coil?
Could some heavy metal shielding help? ......... (PJ contributions to low frequency harmonicas)
PJ you are a DILL (pickled) ...... on a stick!
Huego (with purple harmonics)