Appreciate your comments thank you.
From cold the o/p is steady, after about 20 mins o/p begins to fall all of a sudden
I watched it fall away over about 20 seconds the transverter went from 14w out to only 500mw.
Transverter is ok, I checked with another drive source (FT2000 for 30 mins key down- no issues) and repeated the test the next evening. Once the fans start on the IC-7600 the power begins to return although not to original level.
Like you I'm not using ALC and did not notice anything strange on the meter.
Main o/p on HF seems fine all the way through but 50 MHz is a little on the low side at about 75w max.
Yes I agree the o/p from the Icom is high about -5dbm and I can accommodate this with the OZ2M attenuator & an additional 6db pad but the fluctuation is a real pain as I set up for 160w and end up with about 20w half an hour later so it's at Icom at the moment.
They tested another IC-7600 and confirmed -10.9dbm from cold and -12.9dbm after half an hour or so- not ideal but a lot better than what Iâ€™m seeing here.
Iâ€™ll let you know how it goes, please save some dx for me