A vacuum variable vapacitor (1) comprising a pre-vacuum enclosure (21) for reducing a pressure differential across the bellows (11), wherein a drive means (34; 40) is disposed outside the enclosures(2; 21) of the vacuum variable capacitor (1). The vacuum force load on the drive system can thereby be reduced, allowing faster movement of the movable electrode (7), faster capacitance adjustment of the vacuum variable capacitor (1) and longer lifetimes of the device.