[Elecraft] K3 - Output power instability?

[Stewart Rolfe]

Whilst transmitting today on CW (QSK) at full power, I've noticed on a 
couple of occasions the power meter showing a fairly sudden drop in 
power to around 45 or so watts. It gradually returns to full power and 
then will behave normally for long periods. Each time this has happened 
the radio has been on 80m and the ATU has been in circuit; the power 
setting remains at 100 watts the whole time and the current meter on the 
power supply does suggest that the power is indeed falling. The SWR 
indication remains low and the PA temp stays around 37 deg.

If it continues to happen I will make more careful observations but as 
an initial step thought I'd see if anyone has experienced this or has 
any idea of what may be going on.

73, Stewart Rolfe, GW0ETF (K3 s/n 145)