[Elecraft] Low power out on 6 meters

[K0EKL]

After doing the full calibration multiple times (Synthesizer/Wattmeter/TX
Gain/ and TCXO) I find that I have lower than expected power output on 6m.
Firmware is 1.78 and I have the rig set to transmit through the 2.8 KHz
filter.
 
With the K3's power set to 100 watts I'm seeing 66.3 watts output to a dummy
load on my LP-100A wattmeter.  Set to 120 watts I see a maximum of 76 watts.
Is this normal behavior?
 
Thanks.