Tuning, staggered

An alternate method not used too much at this time is the drum design. The drum construction is somewhat different from the disc, in that the rotor body is of cylindrical construction. By using the hollow drum, conical roots, of bolted construction, can be used for the rotor, again, allowing for stagger adjustments to fine tune the axial compressor to the application if the need arises. The setting is done to a gauge at the factory, as with the stators. 

FIGURE 13.5 Electrode configurations for dielectric heating systems (a) 50 Q technology, a fixed-frequency amplifier and the load are separate, linked together by a matching network to tune the system (b) stray field type for thin webs and (c) staggered type for thick webs or board. 

For television service in the U.S., at least a 5.25-MHz bandwidth is required. Some European systems require as much as 8 MHz. At the power levels used in television service, it is necessary to stagger tune the cavities of a klystron to obtain this bandwidth. This is particularly true at the low end of the UHF band, but less so at the high end where the percentage bandwidth is lower. 

The power of a klystron is Hmited to a theoretical 100% of that in the electron beam Py = / , V ,). In some areas, efficiencies of 70 80% have been achieved. Normally, efficiency of 40-60% can be expected. RF power bandwidth, of course, is dependent on the number of cavities and their tuning. Typically, klystrons with multiple cavities can be staggered tuned to provide a flat RF passband at some reduction in efficiency and gain. For example, in four cavity tubes, staggered tuning results in a-l-dB bandwidth of 1% with a gain of 40 dB. 

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