New Zealand Radio Industry

Radio Record, Volume III, Issue 7, 30 August 1929, Page 30

New Zealand Radio Industry

Inside a ‘Modern Factory

EW people who see "the finished radio set would realise the amount of’ carefnl and intricate work involved before the’ product is finally ready for marketing. Those who have worked and laboured in the construction of even a small wireless set would be amazed to see how the makers of the popular "Courier" Receivers reduce the many involved. operations to simplicity. First of all come the metal bases upon which all components are set up. The bases are already bent to the ‘correct shape, and are then taken to the farthest bench to be pin-stamped ready for drilling and punching. Metal templates are used for this purpose to ensure absolute accuracy. Next comes the mounting of the various parts such as R.F. coils, transformers, sockets, ete. By a special circuit arrangement the metal base is made act as a "return," thus simplifying wiring and obviating "unnecessary joins. It is interesting to note in passing that there is only one "tapped" connection in the whole wiring system. . The drilled and assembled base is then passed’ over. for initial wiringall connections which ultimately go to "earth" are firmly soldered to the base. The semi-wired bases now proceed to the next bench, where they are completely wired up. The final wireman draws the requisite coil assembly from the coil bench and connects its temporarily to the receiver ready for test. All these tuning coils are hand-wound on @ rotating jig, the wire passing through a wash-leather grip to ensure freedom of hand-moisture. Larger coils requiring many thousands of wire turns-low frequency chokes, ete.are wound on a power-driven winder with a friction clutch and throw-out. The wiring staff employed are taught to work not from theoretical diagrams but from plans which show the receiv-er-base upside down, with vari-coloured lines joining passing over or entering the appropriate hole. This method overcomes wiring errors and makes for greater wiring speed. Nevertheless, each wireman is required to have a thorough knowledge of the cirenit he is working on so that he can be always alive to possible sources of future trouble. After wiring, the nearly-finished receiver is put through a series of searching tests. The valves are then plugged in and the receiver subjected to: a thorough checking and examination whilst actually "on the air." A. local modulated : oscillator, completely screened and accurately calibrated, is used for checking up the tuning circuits and general. continuity, while a meter board is. brought, into use for testing leakage or high-resistanee "shorts," ete. Valve currents are carefully considered and made to compare with a standard before being passed... A special arrangement of an electric. gramophone pick-un and lower-power oscillator is then switched on and the receiver under test tuned to this apparatus: thus

picking up. the modulated. wave as a high-frequency "broadcast" signal. This method can be used: very successfully in checking sensitivity, selectivity, tone and volume; ete, Altogether the testing arrangements are: comprehensive and rigorous and probably call for the most specialised knowledge of all. As the engineer in charge said: "Anyone can wire a receiver, but not one man in a 100 can test it as it should be tested." After final test and pass-out’ Le skeleton receiver is passed over nother man who installs it in its appropriate cabinet and makes everything secure. .It then goes on t).. yet another member, who again subjects it. to the same series of tests as applied -previously, thus giving each receiver at least a dual test. .The final tester calibrates the tuning ehart accompanying each receiver by means of the modulated oscillator-wavemeter. All coils, grid leaks, resistances, condensers, and transformers are separately examined and tested before being put into use-coils and tuning condensers particularly. Everything that could possibly be made here in New Zealand the "Courier" factory constructs so that as large a measure of independence as possible may be atz-« tained. The ingenious and effective coilassembly calls for particular comment. ' As everyone knows, the "Courier" engineers patented and used a combined high and ‘low wave receiver. They said "a flick of the switch" eighteen months ago and now manufacturers of America and Great Britain are following the lead. The "high-low" coil mount proved to be of great interest and was a model of neatness and rigidity. The whole unit.is backed on to a small bakelite panel and is fully wired quite separately from the receiver. , To bring the complete assembly into use it. is thrust through an-oblong aperture in the cabinet back, screwed home and wired on to the receiver. The interesting: feature is that the complete unit is joined to the receiver by only two wires. This means that the whole complicated tuning systems for both sets of waves can be brought into service by: merely connecting iv0 small leads-a great advantage iy; e and assembly. This "unit" process can be followed out in all the processes leading to the finished: receiver. The engineer in charge has. obviously devoted much time and thought to ‘his policy, and has certainly suceeeded in reducing the whole rather complicated process to a series of simple operations each fitting one into the other like a jig-saw puzzle.