The rotor of a variometer or variocoupler is a rotating coil.
This is the part of the variocoupler that is called the stator.
Now connect one end of the secondary coil, or rotor, of the variocoupler with one post of the .0005 mfd.
A diagram of a variocoupler is shown at A in Fig. 53, and the coupler itself at B.
Don't fail to put a copper shield between the variometer and the variocoupler.