Glossary of Wireless Terms

Radio Record, Volume II, Issue 9, 14 September 1928, Page 28

Glossary of Wireless Terms

From week to week we give here asection of the glossary of wireless ‘ terms from the "Listener’s Guide."

NEGATIVE.-Every cell or battery of cells has two electrodes or poles, a positive and a negative, which are usually clearly marked respectively "+" and "7 The positive pole is often further distinguished by red paint, and the negative by black or blue paint. In any instrument or compound employing a permanent magnet (such as a telephone receiver) polarity is generally indicated and should be observed. Positive, or -+-, corresponds with the north pole of the magnet, and negative, or -, with the south pole. NEUTRODYNE. — Originally an American cireuit in which, by the use of tiny adjustable condensers, the inherent capacity existing between the internal electrodes of the valves is neutralised. Properly used, a neutrodyne receiver is much more manageable for long-distance, ordinary broadcast wave reception than a set in which such neutralisation precautions are not taken. OHMW’S LAW.-A fundamental electrical law, eonceived by George Simon Ohm (1787-1854), an electrician of fame, affording computation of one of the following :-Resistancé, voltage, current- if the figures for the other two are known. According to Ohm’s Law: Current (in amperes) equals voltage divided by resistance (in ohms) ; resistance (in ohms) equals voltage divided by current (in amperes); voltage equals current (in amperes) multiplied by resistance (in ohms).

OSCILLATING VALVE.-A valvg s6 operated that it will produce oscillatiéns. This is usually accomplished by means of a reaction coil coupled back from the plate circuit to the grid cireuit, thus sending back properly timed impulses capable of exciting the grid of the valve and thereby sustaining the action and reaction effect indefinitely, energy being drawn from the batteries or current generators in use. An improperly operated receiving set, unless it is correctly neutralised or balanced by neutralising condensers, will cause the detector wave to oscillate and thus energise the aerial, occasioning interference with other listeners. A definite test is to turn the tuning dial or dais of the receiver slowly, and if the station being listened to moves smoothly from minimum to maximum and minimum again without a sound of a whistle which alters in tone precisely in step with the movement of the dial, then the receiver is clear of interfering effects designed to distort or ruin the reception of signals either on the set in question or others in close proximity. A good rough-and-ready test for oscillation is to wet the finger and touch the aerial terminal with it. If a loud "click" is heard every time the finger both touches and leaves the aerial terminal, you can be certain the set is oscillating and causing interference with other listeners. OSCILLATING CURRENT.- Sas the same characteristics as alternating current, but takes place at a radio frequency. See "Alternating Current."