Re: [Amps] Checking for IMD

["Gary Schafer" <garyschafer@comcast.net>]

> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Tom W8JI
> Sent: Monday, August 14, 2006 2:49 PM
> To: garyschafer@comcast.net; amps@contesting.com
> Subject: Re: [Amps] Checking for IMD
> 
> > What is your point?
> 
> To try and help everyone understand what it does and what it
> cannot do and how it works.

The wrong things shouldn't be exaggerated then. We should focus on what
really happens.

The S meter doesn't measure "peak power". A more correct statement would be
it measures the "average power of the peaks" (as in peak envelope power).
But it is immaterial as it is the same meter that is being used to measure
the fundamentals as is used to measure IM levels here.

"misses some of the third order and much of the higher order products" is a
misleading statement too. In reality there is a sampling of all of those
products with voice being used as it is a wide spectrum of tones generated.
The resultant IM products will be represented in a rather narrow band.

"probably isn't useful on the air except under certain conditions". No test
of any kind is useful under all conditions. There are always limitations. 

> 
> Who's going measure the dynamic range of various radios
> using S meter movement?

If someone measured their transmitter with their poor performing receiver
and thought they had poor IM performance on their transmitter maybe that
would be a good thing. That may prompt some further action into
investigating why.
Seems better than to just throw up our hands and say "it's too complicated
to try we're going to get the wrong answer".

73
Gary  K4FMX

> 
> 73 Tom


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