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[Amps] RE : Checking for IMD

To: "'Jim Tonne'" <tonne@comcast.net>, "'Tom W8JI'" <w8ji@w8ji.com>,<amps@contesting.com>
Subject: [Amps] RE : Checking for IMD
From: "hermans" <on4kj@skynet.be>
Date: Fri, 11 Aug 2006 22:44:10 +0100
List-post: <mailto:amps@contesting.com>
What about asking Joseph Fourrier?

Jos on4kj  ( (sorry Jos couldn't resist). 

-----Message d'origine-----
De : amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] De la
part de Jim Tonne
Envoyé : vendredi 11 août 2006 21:44
À : Tom W8JI; amps@contesting.com
Objet : Re: [Amps] Checking for IMD



Tom wrote:

> Also there is a basic flaw with two-tone tests. Two-tone
> tests don't vary the power supply loading like a voice 
> signal would. Flaws in grid voltage or high voltage dynamic 
> regulation may not show at all. Almost always the error 
> makes things look better than they really are.

And Jim is adding:

Very true!  And if the separation between tones is down 
below, say, 100 Hz, then the power supply regulation (or 
lack of same) starts to enter into the picture.  To test the RF block alone
be sure to use separation of at least 1 kHz. But to test the entire system
we have the dilemma of how to simulate voice.

How pure does each tone of a tone pair have to be to
check IMD using a two-tone test?

- JimT


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