[Johnson] Viking 1 tuning

[John King]

I am having real trouble getting the exciter stages of my Viking 1 to tune as they should they were tuning up and providing drive to the final, but then the exciter stage stopped tuning as it should in the OSC, Buffer,Drive and Grid readings.
I have replaced the 6AU6, and 6AQ5 tubes with no improved results. I also changed the 6AL5 bias rectifier.

I am extremely frustrated by the malfunctioning exciter section. I have four other transmitters on the bench awaiting parts and finishing the Viking 1. 

I had the Viking pumping out slightly over 100 watts and then the problem popped up. I replaced the audio driver transformer.

My conclusion is that the exciter stages in the Viking 1 are just very unstable and the instructions in the manual don't help me very much. Has anyone had a lot of first hand experience with the Viking 1 tuning and experienced the on again off again functioning of those stages. If so, I will greatly appreciate your assistance. The only tuning control that shows changes in tuning is the drive control. The oscillator and buffer controls make no difference in tuning. The Viking 1 is a simple transmitter but it is frustrating me. Thanks and 73, John, K5PGW