[Lowfer] Vacuum Var C Help ?

[Ed Phillips]

Peter Barick wrote:
> 
> How is a Vacuum Variable Cap tuned, ie, how is the vacuum maintained
> while the rod or shaft is actuated? Is a diaphragm used with the
> actuating rod on one side and the vari stuff on the other?
> 
> Further - are they prone to leakage over time? Then how tell?
> 
> Peter

1. Yes, the plates are moved by a lead screw pressing on the end of the
bellows.  The plate spacing is surprisingly tiny.

2. Not in my experience.  I have the remains of a beautiful 10 kV (RF)
1000 uufd VVC which a technician ruined by drilling a hole in the
bellows.  God bless guys with 5 thumbs on each hand and not a brain in
their head!!!!!!

Ed