It’s much easier to check the output of the tube for proper TEM00 resonance or mode. If the tube is in question and it isn’t in TEM00 mode, it will never work or align properly along with poor operation.
If you have
- properly working tube
- clean and aligned optics
- proper focus
They work.
Start with the tube…
If you don’t see an issue with it’s mode, then I’d move on…
One of the guys on another site has a K40 and claims to have run his for the pase 7 years…
