[Amps] Measuring IMD

[peter chadwick]

The reference given to Pappenfus gives the equations for determining the level of 3rd and 5th order products from the curvature of the line.

Noise testing is good, provided you are sure about the peak to average ratio: to that end, noise with a notch in the middle of the AF passband leading to measurement of the IMD power in that notch is good. The technique was used over 50 years ago in measuring FDM telephone systems, and was applied to multichannel HF SSB tx's.

The question  at the end of the day is 'How much use is the information about more accurate levels of IMD measurement except as an academic exercise?' More to the point is the IMD power in a SSB bandwidth at various offsets - as SM5BSZ has measured. Plus the fact that the vast majority of amateurs neither understand or care about how bad their tx is to the last few dB!

73

Peter G3RZP