The paper deals with a new technique for the generation of r.f. signals for television testing. A signal generator tunable continuously through all the television bands is described. The operating principle is based on the generation of sound- and vision-modulated test signals at the standard intermediate frequency followed by broadband frequency conversion to the range 25 to 1000 MHz. The method is justified in a description of the technique of up-conversion to a high intermediate frequency with subsequent broadband down-conversion. This is followed by a presentation of the specification necessary for the local conversion oscillator, together with its operating principle and electrical characteristics. The method of frequency stabilization, indication and tuning is looked at in greater depth. In conclusion, the characteristics of the overall system are discussed, including a description of the modulator section, and the wide range of applications indicated.