Low RF Output on SSB

PROBLEM: RF Output power below 100 watts on SSB. This weekend I operated the SS Phone contest field-day style from a mountaintop. When the rig was powered up Sunday morning, I couldn't get more than 50W output on 10m.

SOLUTION:  It was cold... a bit above freezing. After it warmed a bit (15 minutes), full power was restored.
Hopefully, your problem is as easily solved. 73 de Bob, K6XX