New modulation techniques for increased efficiency in UHF-TV transmitters
The use of electron-beam modulation in klystron amplifiers is an important means of reducing the electrical power consumption of ultra-high-frequency power amplifiers, employed in the transmission of television signals. This paper explores the characteristics of the amplifiers, describes the methods developed for applying video modulation, and gives details of typical power savings which can be expected.
The television performance of the klystron amplifier
The paper describes the electrical behaviour of multi-cavity klystrons, now extensively used as high-power amplifiers in u.h.f. television transmitters. The factors affecting the frequency response are reviewed, with descriptions of the particular conditions required for output coupling and cavity tuning. The response of the klystron to the television tests for non-linearity is discussed in detail, and it is suggested that (a) differential phase shift is produced by the basic a.m.-p.m. characteristic of the tube; and (b) the discrepancy between observed results of line-rate linearity and differential gain tests is due to differing amplification of single and double sidebands, to be expected with any non-linear transfer characteristic. This discrepancy can be removed by suitable signal processing in the transmitter.
5.63 and 5.80 MeV levels of Ne20; de-excitation branching
Abstract The ratio Г γ /Г for the 5.63 and 5.80 MeV levels of Ne 20 has been determined to be 0.077 (±0.008) and −4 , respectively, by using the C 12 (C 12 , α)Ne 20 reaction and determining the fraction of the events in which the alpha-particle and the Ne 20 recoil are present in coincidence at the kinematically correct angles. In both cases these results in themselves are shown to imply radiative E1 transition (5.63→1.63 and 5.80→0, respectively) probabilities ⪡5 × 10 −5 Weisskopf units. When taken together with the life-time for the 5.63 MeV level measured by Evans et al . values of Г( E1 ) ≲ 5 × 10 −6 and Г α ≈ 6% of the particle estimate are obtained for this state.