Amps
[Top] [All Lists]

Re: [Amps] Measuring IMD

To: amps@contesting.com
Subject: Re: [Amps] Measuring IMD
From: peter chadwick <g8on@fsmail.net>
Reply-to: g8on@fsmail.net
Date: Sun, 03 Nov 2013 22:25:53 +0100
List-post: <amps@contesting.com">mailto:amps@contesting.com>
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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>