[AMPS] IMD

Steve Thompson g8gsq@qsl.net
Tue, 18 Sep 2001 16:20:17 +0100



-----Original Message-----
From: Peter Chadwick <Peter.Chadwick@zarlink.com>
To: 2 <2@vc.net>; @AMPS <amps@contesting.com>; 'John T. M. Lyles'
<jtml@lanl.gov>; 'G8GSQ' <g8gsq@qsl.net>
Date: 18 September 2001 16:10
Subject: RE: [AMPS] IMD


>
>Steve said:
>
>>So when the spectrum analyser shows -50odd 3rd order IMD out of my 2m
>>transverter at 15W pep from a bipolar PA with no rf nfb, it's telling
lies?
>
>Quite possibly! You know as well as I do that given the ghost of a chance,
a
>spectrum analyser will lie like a personnel  manager (and they make
politicians
>look honest!) A DSP based spectrum analyser fed from a FET probe and you've
no
>chance of the truth.........
I know it all to well, which is why I'm confident of the measurement. I've
rarely seen a situation where measuring system problems make *all* the
intermods look better, which is usually a giveaway. If there's doubt, I
double check with the trusty old 141.

Steve


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