Let us know what the final outcome is Julian. I have a similar problem with an original 20m QCX. It has worked well and had numerous QSO's. I couldn't get more than about 1.6w out of it. Had a go at tuning it up recently and got to 2w and that's it.
No amount of coil compressing or expanding gets it any better. I had also removed a couple of turns from L3. Funnily enough about the only measurable improvement came when I altered the spacing on L4, I think it upped the output nearly 1/2w when I opened out the turns. I reckon I might have to have a look at changing the relevant capacitors but have got a couple of other projects on the go at the moment so it is not urgent. Alternatively... I might just leave it at 2w I reckon another 3w isn't going to fry the F layers. Anyway..? interested to see what you find with the one you are working on.
Reg?????????????????????? G4NFR
