[Amps] IMD test question

[Dan Mills]

On Wed, 2012-08-01 at 16:19 -0400, Gudguyham at aol.com wrote:
> Bill, I'm SURE with today's multitude of hams with SDR radios, you should  
> easily get dozens of hams to give you "on the air" results.  It seems there  
> is a lot of IMD cops out there.  Pick one.
>  

Trouble is most of 'em don't know how to tell the difference between
your IMD and their receiver overload!

Rx connected to a PC with a decent sound card and some known attenuators
is a reasonable stab for things like amplifier IMD (where you are not
trying for monster IMD3DR, it gets much harder when looking at things
like good first mixers as everything becomes very critical. 

Use the sound card output to produce the two tone pair to feed the SSB
modulator. 

Judicious use of attenuators at various places in the chain can allow
you to use the third order behaviour to figure out where the dominant
IMD source is.

If you use Linux, then the jack audio connection kit in combination with
the JAAA audio analyser gives you what you need (Generation and audio
spectrum analysis). 

73 M0HCN