[Amps] MOSFET amp filtering - was: auto-tune

[Jeff AC0C]

The general rig's filter method constrains bandwidth in SSB only down about 
30 db or so.  Then the typical rig gets fat flaring out from there.  In some 
cases, they get VERY fat, very fast.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: Jim Brown
Sent: Monday, December 12, 2016 7:37 PM
To: amps at contesting.com
Subject: Re: [Amps] MOSFET amp filtering - was: auto-tune

On Mon,12/12/2016 2:18 PM, Manfred Mornhinweg wrote:
> But is it in an RF amplifier?  Really?

Spend a bit of time on any ham band with a spectrum analyzer that has
good frequency resolution and you'll learn in the first 30 minutes that
this is true.

Or take a look at pictures from mine looking at CW and SSB signals.
http://k9yc.com/P3_Spectrum_Measurements.pdf

Or Fig 1 on page 3 of http://k9yc.com/ContestAudio.pdf

Or set up a 2-Tone IMD test using whatever generators you happen to have
in your lab. The Elecraft K3 has one built-in. See K6XX's test results
here. http://k9yc.com/K6XXAmpTalk.pdf

The splatter MUST be created in the power amp -- AF harmonics outside
the SSB filter will be suppressed by that filter.

73, Jim K9YC


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