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.
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