GB932160A - Improvements in and relating to signal amplifiers - Google Patents

Abstract

932,160. Electric analogue computers. PHILCO CORPORATION. Nov. 29, 1961 [Nov. 29, 1960], No. 42651/61. Class 37. [Also in Group XL (c)] Variations in electron transit time, and hence in phase shift, in an electron multiplier to which automatic gain control is applied by means of an un-by-passed resistor connected in series with an intermediate electrode of the electron multiplier, and occasioned by variations in the potential of said intermediate electrode as the signal level changes, are reduced or eliminated by a suitable choice of the bias applied to said intermediate electrode for a mean value of current flowing through the unby-passed resistor or by inserting a resistor in series with the anode of the electronic multiplier to produce a compensating change in potential there with changes in signal amplitude. In a first embodiment, Fig. 1, resistors 17 and 18 are so chosen that when current flowing in A.G.C. resistor 22 corresponds to an average value of signal level, the potential of electrode 5 is midway between the potentials of electrodes 4 and 6. In a second embodiment, Fig. 3, resistor 18a is made much smaller than resistor 17a so that due to the voltage drop across A.G.C. resistor 22a the voltage difference between electrodes 5 and 6 is very small and secondary electrons travel directly from electrode 5 to anode 12a. Compensation for variations in transit time between electrodes 4 and 5 with signal level is then effected by means of a resistor 23 inserted in the anode circuit of the electron multiplier; this causes the anode voltage and 12a to vary with signal level in such a manner that the overall transit time between electrodes 4 and 12a does not change.