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Re: [Amps] How to read the 3-500Z spec sheet?

To: <>
Subject: Re: [Amps] How to read the 3-500Z spec sheet?
From: "Jeff Blaine AC0C" <>
Date: Sun, 23 May 2010 16:15:34 -0500
List-post: <">>

There are 2 ways to look at this.  If you look at it from a "is this the 
official lab-standard proper way" standpoint, it comes up a loser.  I'm not 
suggesting it is.

And If you look at it from a "is it a step in the right direction" and "can 
it be done by average joe ham for a few bucks" and get somewhat interesting 
results - the answer is yes.

If guys want to keep peppering me with the details of proper IMD 
measurement, we can do that - but it's a sidebar to my key point.  I get it. 
This is not a proper Grandberg setup.  So for all those guys who are reading 
this or are sending me little off line mail about "IMD measurements 101," 
give me a break.  You are missing the point.

Better the guy use a ruler to measure things than none at all.  If one 
headlight burns out in my car, I don't turn them both off because "if it's 
not perfect, then it's not worth doing."  There is no point to debate that a 
ruler is not as good as a caliper and my mailbox is filled with guys making 
that comment.  Even if the ruler is a gross approximation, the simple effort 
of looking at it raises awareness in an area of the hobby that as far as I 
can tell, gets damn near zero attention.  Well unless someone mentions 
certain down-under amp suppliers, anyway.

Is better to have some newbie cranking away on his amp or his rig without 
any thought at all to the stuff going out his pipe - than it is to have him 
use less than perfect test setups?  Not here, at least here in the fly over 
country of KS.

But then again, I've got a lot of inbox nonsense suggesting I don't know 
what I'm talking about.  Maybe that is the case...


From: "Martin Flynn" <>
Sent: Sunday, May 23, 2010 3:06 PM
To: "Jeff Blaine AC0C" <>
Cc: <>
Subject: Re: [Amps] How to read the 3-500Z spec sheet?

> Jeff,
> Is using a sound card good enough?  One of my elmers <sk>  had a dedicated 
> two channel audio generator for testing.
> Motorola published a white paper by  Helge Granberg  on IMD measurements: 
> Martin
> Jeff Blaine AC0C wrote:
>> Of course, a real IMD test requires a 2 -tone source and you can download 
>> those applications on the web free of charge.  A good quick and dirty 
>> solution is to switch your digi mode application over to PSK.  In fact, 
>> if it were up to me, it would be a legal requirement for all PSK ops to 
>> have station monitors of this type when running PSK.  Lot of 
>> misinformation and nonsense in that community among the rookie ops.

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