Laboratory Test

Radio Record, Volume III, Issue 28, 24 January 1930, Page 29

Laboratory Test

7 Atwater Kent Model 60 C _& A, ODLIN, LTD., have supplied * us with an Atwater Kent receiver, Model 60, and during the last few weeks we have been able to test this to our satisfaction. In connection with this receiver, it is interesting. to note that it was the first of its type introduced into the country. The circuit comprises three stages of a.e, Sereen grid, detector (227), resistance coupled to the first audio, "also 227’s and.two 245’s in the last stage. Rectification is accomplished by a full wage 280. Detection is carried out by The grid condenser method. . On lifting the lid of the receiver one eannot help noticing the very neat and efficient appearance. All the components are shielded in uniformly enamelled metal covers. The valves are not an exception. The result is a very robust receiver, perfectly shielded, and humless. On reversing the receiver, and removing the protecting plate, the wiring is disSclosed.- The few components in this part of the receiver are well eonstructed so- that trouble in «this direction will not be likely. There are three controls: the tuning control, which, by means of a brass belt, moves the four tuning condensers and the illuminated dial graduated in ‘ degrees and kilocycles; a volume control, and a local station switch. Our ¢ttests reveal that the marked frequencies were slightly in excess of the frequency of the stations received: Volume is controlled by a variable resistance connected in the circuit of the auxiliary grid of the second and third radio amplifiers. . The local station switch taps the primary inductance of the second R.F. transformer, so that either the, whole o® part of this coil can’ be placed in the circuit at will, Volume is thus greatly reduced without introducing distortion. On the local station, however, it was found that other means had yet to be taken to sufficiently subdue the signal. Connecting to the terminal marked "short antenna" a length of insulated lighting wire and twisting this round a convenient place outside, we found formed a very effective aerial for use on the local station. . Even then the set worked better-that is, volume was more contrg@@able and quality better ‘maintained sen, the earth connection was removed. , The sensitivity of the set is greater by far than that of our standard model, in fact it surpasses in this quality any set we have yet tested. During the summer months in which reception is notoriously bad a fairly representative log of stations was received. A calibration curve is published showing the major stations received and their positions on the dial. Far more volume than required was obtainable from all New Zealand "A" stations, as well as on: several of, the smaller, Christchurch could be brought in on the very ‘ small aerial previously mentioned, and seen oon EE —

by y using t this static was very much subdued. Following is a gelection from the stations received, with the dial reading for each :-2YB, 13; 1ZB, 20; 2ZF, 23; 2UH, 24; 3YA, 27; "1A, 38; 2BL, 36; JOOK, 39; 47; 4QG, 48; 2YA, 55; oF, 65; 4YA, 67; 3AR, 75; 2ZK, 80; TZL, 8&8. was good and by using a 180-foot aerial, 2FC could be brought in when 2YA was operating. The tested voltaves were as follow:

There is'an entire absence of hum while the set is perfectly stable even on the higher frequencies. Accompanying the set was a dynamic speaker which can be used with no other; likewise no other speaker can be used with this set. Being low set, the speaker has a delightfully mellow tone,

; Sereen. Plate, 1st Radio Frequency 140 180 2nd Radio Frequency 10-120 165 8rd Radio Frequency 10-120 165 Detector e@neecesea , 110 ‘Audio @eoeseeeer 160 Power ° eveeseenecs . 260 Filaments (average) 2.45