[Amps] IMD test question

[Mike]

You would have to ask them if they had their Noise Blanker on first: -)

Mie

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Dan Mills
Sent: Wednesday, August 01, 2012 1:33 PM
To: Gudguyham at aol.com
Cc: amps at contesting.com
Subject: Re: [Amps] IMD test question

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

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