Air Variable Capacitors

17-300pF air variable capacitor.

Air Variable Capacitor

Our air variable capacitors have a range of 1.7pf to 300pf. Each cap is constructed using precision CNC plasma cut vanes for both the stator and the rotor. Each cap includes our own contactor wheel and arm design. Our contactor arm tension is completely adjustable and does not rely on assembly pressure to hold contact pressure between the RF connector and the rotor.

Source and Load Caps

In this example, the capacitors have been installed on the bottom side of the mid-plate in our symmetric antenna tuner. Each cap has a shaft RF isolator and a 4.5:1 vernier reduction drive installed. Note the solid construction of these caps. No flimsy material being used here. Additionally, each cap is completely serviceable. These caps can be disassembled all the way down to the individual plates.


Capacitance: 17 - 300 pF
Voltage: 3-5KV spacing
Length: 6in
Width: 4in
Height: 4in

Split Rotor Capacitor

The split rotor cap was specifically designed to address mechanical balance issues on the rotor. By splitting the rotor plates in half and then rotating half of the plates 180 degrees, the rotor becomes perfectly balanced. This eliminates backlash in the system caused by rotor plate weight.

An additional advantage of this design is that the stator plates can be electrically disconnected from each other (each set). Additional switch gear can be utilized to reduce the minimum value of the capacitor by half.

1100pf split rotor cap

This capacitor was specifically designed to be used in the new ATU4k (ATU4K ) tuner, which is a collaboration between and Blue Ridge Amateur Radio.

This cap has a maximum value of 1100pf and a minimum value of 23pf. The cap is a split rotor design, which allows the larger part of the cap to be electrically removed from the smaller portion of the cap.

It's hard to tell in this picture, but this cap is the size of a loaf of bread.