Sorry to bother you again, I have an 8340B options H01....
above 25.7GHz setting a power level greater than about 3dBm shows an unleveled message... which is normal and goes away when the power level is set to a lower value.
The problem is when, for example, the power level is set to something higher (well above the capabilities of the instrument around 26GHz) like +10dBm (with the knob or by entering the a value with the keypad).... unleveled message shows up (output power goes way down) and it does not go away until the power is decreased to around -10dBm, then it can go up to around +3dBm.
It seems that if the power level is set to high, the unleveled condition sort of locks up.... which is a problem with the 8510C since it set the default power level to 10dBm and above 25.7GHz it losses lock.
Is this normal, I could not find much about it on the manuals.
I believe this operation of automatically decreasing the power is normal - as if you ask the 8340 to generate too high a power level you are really pushing some very expensive and now probably unavailable power circuits/amplifiers.
Unfortunately, we do not have all the information on the 8340 series.
Hopefully someone from the Forum community can step in and assit.