Television Receiver Design Trends in the U.K.

In spite of the similarity in the Domestic television market U.S. and U.K. receiver designs differ appreciably. In the U.K. virtually all receivers are hybrid, valves being retained for the output circuits only. In the signal amplifying circuits transistors can give improved noise performance, particularly at U.H.F., and varicap diodes simplify the mechanical aspects of the tuner. The video and signal processing circuits are again ones that lend themselves to transistor circuitry, particularly in the case of colour receivers. The power supply for a transistor receiver imposes a cost penalty and conventional tube circuits provide the most economic solution for the scanning system. High voltage semiconductor diodes, however, can simplify the e.h.t. generator circuit in a colour receiver. The combination of transistors and tubes pose many problems to the receiver designer. One major hazard to transistors is the effect of picture tube flashover. This gives rise to excessive voltage and current transients in a receiver and protection is necessary.