Experimental investigation of the multisignal operation of microwave tubes

The results to be described herein concern the multisignal operation of a UHF Crestatron (100-300 MHz) and an S-band TWT using a tapered helix. The Crestatron was operated with two input signals (frequencies f1and f2) which were independently varied from low power levels to above saturation. The intermodulation frequencies ( , etc.) generated within the tube were analyzed for various frequencies, frequency separations and relative power levels. Generally the results indicated that the intermodulation and second harmonic signals were proportional to the input power. With one saturated signal and one small-signal applied, the intermodulation frequency associated with the stronger input signal predominates. However, with two large input signals the stronger intermodulation signal depends on the frequency of operation.