i really need some notes on how a thermonic valve works as a - a) h. p. amplifier,b) detector.....?

Question

and c) L. F. Amplifier in a wireless set and also how a "westector" works.
i'm desperate!

Answer 1

Thermionic valves or vacuum tubes basically work by the emission of electrons from a heated cathode which are collected at an anode. This simple tube acts as a diode (detector) because electrons can only flow from cathode to anode, not the other way. Addition of one or more grids enables controlling the electron flow with a voltage at the grid(s). These tubes (the first was called the audion tube) are referred to as triodes, tetrodes, etc. depending on the number of electrodes (grids + cathode + anode). An early paper on this is in ref. 1. More advanced construction and application are discussed in ref. 2.
The Westector was a small copper-oxide rectifier marketed in the 1930s. See ref. 3.
A detector in those days was a means to demodulate (recover the modulating signal from) an AM radio signal. (Now, detection has a broader definition.) Ref. 4 provides the general idea of AM detection.