Abstract :
A travelling-wave tube requires stable h.t. and e.h.t. supplies, and, in some applications, stable solenoid focusing and d.c. heater supplies. These may have to be derived from a low-voltage d.c. source, such as a battery, having a wide variation in output voltage. Heater and variable h.t. and e.h.t. supplies of adequate stability, small size and high efficiency can conveniently be obtained using transistorized d.c./d.c. convertors preceded by a voltage regulator. At low powers the voltage regulator may be of the simple series type, but for high output powers a regulator operating in the switched mode is preferable. This method is capable of development to control power outputs of 200 or 300 watts with an accuracy of ±¿% and should prove an attractive way of providing regulated solenoid power for electromagnetically focused travelling-wave tubes where an unregulated supply is inadequate. The operation of d.c./d.c. convertors is discussed, with particular attention to means of stabilization and the provision of a wide range of output-voltage variation. Typical supply systems using these circuits are briefly described. The work on these has been primarily directed towards providing power for travelling-wave tubes, but similar systems are equally suitable for many other devices such as cathode-ray tubes, klystrons, etc.
