What is the limitation, the close-spaced IM of the typical receiver, or
is it actually a limitation in Spectrum lab's FFT algorithm (I haven't
tried resolving closely spaced signals with spectrum lab)?
I have done some very crude tests here with 1 KHz tone spacing
and using the CW filter in my R4C and a step attenuator to resolve
level of IM sidebands coming from my rig. The levels seem about
right, but I have never done any tests to validate this (I don't have
a spectrum analyzer here).
This brings up another question that I have been meaning to ask.
When testing amplifiers how does ARRL generate the two-tones.
Are they high level combining the output of two trasceivers each
generating a CW signal, or do they combine tones at a low level
and run them thru an ultra clean "golden" PA?
Mike, W4EF.............
----- Original Message -----
From: "Tom Rauch" <w8ji@akorn.net>
To: "AMPS" <amps@contesting.com>; "Peter Chadwick"
<Peter.Chadwick@zarlink.com>; "Mike" <W4EF@dellroy.com>
Sent: Tuesday, September 18, 2001 6:59 PM
Subject: Re: [AMPS] IMD
>
> > Has anyone had any luck using receiver feeding a soundcard in
> > conjunction with a program like Spectrum Lab to resolve the closely
> > spaced IM sidebands from a PA?
>
> No, and it won't work in that application Mike.
>
> I do use spectrum lab for receiver testing, but only to sort out the
> desired signal from filter blowby and other noises.
> 73, Tom W8JI
> W8JI@contesting.com
>
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