. (The) oscillation valve in the transmission and reception of radio messages . ussed above, it may be saidthat while the tube is acting as a detector (rectifier) itis also acting as an amplifier - that is, oscillations ofgreater power are produced in the plate circuit for a givenalternating voltage in the grid circuit than would beproduced if the same voltage were applied directly to theplate circuit. CASCADE AMPLIFICATION BY THE VACUUM VALVE It has been shown that a single valve will exertan amplifying action on the incoming oscillations. That is,the output (plate) circuit current is simplif
. (The) oscillation valve in the transmission and reception of radio messages . ussed above, it may be saidthat while the tube is acting as a detector (rectifier) itis also acting as an amplifier - that is, oscillations ofgreater power are produced in the plate circuit for a givenalternating voltage in the grid circuit than would beproduced if the same voltage were applied directly to theplate circuit. CASCADE AMPLIFICATION BY THE VACUUM VALVE It has been shown that a single valve will exertan amplifying action on the incoming oscillations. That is,the output (plate) circuit current is simplified in respectto the input (grid) circuit current. Now if we connect theoutput circuit of one valve to the input circuit of a secondvalve, and so on, still greater amplification will this kind of circuit the valves are said to operate incascade. In this type of circuit, however, we must stillmake provision for detecting or rectifying the alternatingcurrent. So in Fig. 12 () the first tube acts as anamplifier and the second as a detector. To sacondarsjCircuit oj. A-(llament li^atttr - I t 5-or amlphSyiA, -L- ^ Bj= T/ata bat tarySor daticTin,,tuk>Q . ^ r-Ka ■Pr.^<,,i,U, 0„d<i.^ly,r.^ /Zed. 4 The primary of a transformer is generally con-nected in the plate circuit of the first tube, and thesecondary in the grid circuit of the second tube, for stillgreater efficiency. As can be seen from Tie, 12, the sameA battery may be used for both tubes. If further amplification is desirable, the alter-nating current from the secondary of the transformer (stillat radio frequency) may be delivered to the input (grid)circuit of a second amplifying tube, and the output circuitthis second tube (current also at radio frequency) connectedto a third tube acting as a detector, or a crystal rectifiermay be used in place of the third tube. An amplifier suchas the above is said to have two stages of amplification. An amplifier in which the signal is amplifiedbefore reaching the
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Keywords: ., bookcentury1900, bookdecade1920, bookidtheoscillati, bookyear1922
