Re: [K2] single tone test - output seems amplitude-modulated

Posted by Geoffrey Mackenzie-Kennedy on Mar 10, 2010; 1:09am
URL: http://elecraft.85.s1.nabble.com/K2-single-tone-test-output-seems-amplitude-modulated-tp4706101p4706382.html

Hi Oleg,

One possible cause for the modulation you see could be a test tone harmonic
generated by your PC, or by the K2's audio circuits.

If, for example, your PC is generating a 1000 Hz  test tone *and* a 2000 Hz
harmonic, then the output of the transmitter in SSB mode will be a carrier
modulated by a 1000 Hz signal. The output carrier is the 1000 Hz tone
translated up to RF, and the 1000 Hz "modulation" is caused by the 2000 Hz
harmonic translated up to RF.

Can you look at the output spectrum of your PC when it is generating a 1000
Hz test tone (disconnected from the K2) and measure the level of any
harmonics relative to the level of the 1000 Hz tone?

73,

Geoff
GM4ESD



dl0tuh wrote on Wednesday, March 10, 2010 at 12:00 AM:

<snip>


 > I hope somebody can help me explaining the first oscillogram - where is
this
> AM
> coming from?




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