what is anode capacitance?

Question

picture tube elements

Answer 1

In electronics, a vacuum tube (U.S. and Canadian English) or (thermionic) valve (outside North America) is a device generally used to amplify, or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. For most purposes, the vacuum tube has been replaced by the much smaller and less expensive transistor, either as a discrete device or in an integrated circuit. However, tubes are still used in several specialised applications such as audio systems and high power RF transmitters, as a display device in television sets, and to generate microwaves in microwave ovens.

The vacuum tube is a voltage-controlled device, which means that the relationship between the input and output circuits is determined by a transconductance function. The solid-state device most closely analogous to the vacuum tube is the JFET. However, the vacuum tube typically operates at far higher voltage (and power) levels than the JFET.