Antenna tuning coil for the Tesla DTV80 transmitter

The inductance of the movable coil adds up or subtracts to the inductance of the fixed coil, depending on the angle of rotation. Thanks to this, it is possible to exactly tune the antenna to the output stage of the transmitter.

The transmitter used two of these coils, similarly to the two smaller coils near to the cabinet of the driver stage. The size of the coil is set by the output frequency and power of the transmitter.

The material, on which the aluminium conductor is wound, is a special ceramics, the so-called Kalit. It does not absorb the high-frequency energy, so it does not negatively affect the electric parameters of the coil, and it is also resistant to the high voltage, which is present on the coil during operation.

The right bearing of the movable coil is damaged by the electric current, which was approx. 1000 A.