[Elecraft] K3 :: PSK31 output power variation

[Steve Jackson]

My K3 setup is configured to put out about 30W on PSK31, with my sound card dedicated to APSK/AFSK modes and its output locked in place to make that power level at 1250 Hz.  My TX IMD is excellent.

However ... if I select a PSK31 spot where the resultant audio frequency is below, say, 800 Hz, my TX output power drops off precipitously as the audio frequency goes down.

I am in DATA A mode.  It's as if the audio to the transmitter in this mode is sent through my SSB TX EQ settings.

That isn't how it works ... is it?

Of course, I can just adjust my VFO a bit and the AF sweet-spot is restored to the range where no power roll off occurs.  

I would not even have noticed except I just gave some poor FK8 a tough time pulling me out  ;-)  after I responded to his CQ near my indicated band edge, and when he said he was having rough copy, I looked and saw my LP-100 said 9.6W out.  

[Gee, that's about 1000 miles per Watt.  Kewl.]

I am assuming the sound card's output itself has no rolloff.  I don't have a 'scope hooked up to it to see, but I have no reason to believe it does this.

Steve KZ1X/4
K1, K2, K3, etc.