[Elecraft] K2: Problems With PSK

[Jon Perelstein]

I'm having problems with PSK (and other digital modes) on my K2.  CW and SSB 
seem okay.

Rig
------
K2/100, KSB2, power set to 20 watts.   RTTY (Reverse) for PSK.  
MFJ-941E Versatuner to a Carolina Windom about 35 ft in the air.  
SignaLink USB into an Acer Aspire One running Win XP (SP3)

On 80/75 meters, I can get a 1.2:1 SWR.  CW and SSB look good (good forward 
power reading on the MFJ).  However, with PSK, the best I can get is 5 watts 
forward showing on the MFJ, but it needs 5 bars of ALC on the K2.  With 1 bar of 
ALC I get about 3 watts out according to MFJ.

On 40 meters, I can get a 1.0:1 SWR.  CW and SSB look good, and I can get about 
8 watts out on PSK with 5 bars of ALC, and about 5 watts with 1 bar.

30 meters is about the same, but with a few more watts, on 20 meters it's still 
a few more, etc.

CW and SSB are good on all the bands.

I also tried PSK using SSB (USB) rather than RTTY (Reverse) and got the same 
results.

Anybody have any suggestions about where I should start looking to see what the 
problem is?

Thanks.

Jon
KB1QBZ