I think I was fairly careful not to clamp too hard when I mounted it. Either way, I'm not going to touch it. Even if I broke vacuum (which I don't think I did) I'm probably not in danger of arcing over. But, definitely noted! These capacitors are expensive!
Jon
Hi Jon,
If the vacuum failed you would certainly have arcing with a 24 FET rig power level. The vac cap spacing in very small and would barely work as a loading cap, never mind as a tuning cap once the vacuum is gone.
The mechanical set up you presently have should be fine if the stress loading is adjusted and balanced right. Because you have it supported in two places, it will have less stress than the many we see that are mounted in the front only. As already said, much will depend on the stress you introduce. The problem comes when tightening things down and one strut is shorter (or out of alignment) than the other putting a load (like a lever) on the seals/ glass. Or, the RF connections pull on the glass, sometimes from tightening or even thermal expansion or contraction. Or the tuning shaft interface is not flexible enough. We must baby our vac caps just like you would a vac relay or the pins on a big tube.
Also, I would get rid of the bare wire that connects the RF tuning cap and associated RF circuits. Use copper or silver plated strap for all RF connections for function and aesthetics.
I see you have a Plexiglas 1/4" rod to RF isolate the floating tuning cap rotor shaft from burning your hand... :-) Nice machining job on that adapter assembly.
Your construction techniques have greatly improved from your first 3-500Z amplifier and other early projects. Looks very FB now.
T
