[Amps] Checking for IMD

[Tom W8JI]

> What I meant was how clean (free of harmonic content)
> does each of a pair of audio tones (sinusoids) need to be
> if that pair is modulating an SSB transmitter in lieu of a
> speech signal?  If I have a pair of audio sinusoids at, 
> say,
> 2000 Hz and 2500 Hz, can each of them have 1% total
> harmonic distortion and still be useful in IMD testing?

It depends on the transmitter. You'd have harmonics at 4000 
and 5000Hz although down 40dB or more, so I wouldn't think 
it too bad unless a harmonics would blow through the filter 
and wind up on the exciter output on an IM measurement 
frequency.

The real problem is most exciters are dirtier than most tube 
amps, even grid driven tetrode amps.

73 Tom