Glossary of Wireless Terms

Radio Record, Volume II, Issue 4, 10 August 1928, Page 31

Glossary of Wireless Terms

From week to week we give here a section of the glossary of wireless terms from the "Vistener’s Guide."

FILTER CIRCUIT.-Vilter — circuits are used to eliminate unwanted sounds or signals which interfere with reception. Is an essential in A and ‘B eliminators, for instance, to smooth out = impulsive currents into continuous characteristics necessary to operate receivers. FLAT-TUNING.-The opposite of sharp tuning. Lack of selectivity. See "Sharp Tuning." FLEX.-The usual contraction employed for flexible wire composed of many fine strands, such as is used for the suspension of household electric lights. FOIL.-Hither copper foil or tin. foil is customarily used for the plates of fixed condensers.’ FRAME AERIAL.-Another name for a loop aerial. See "Aerial, Loop or Frame." . FREQUENCY.-Inu alternating = currents the number of complete cycles or reversals of current through a circuit} per second. Thus, we :s@eak of a GO-eycle eurrent as. one which ha: sixty compleic reyersals per second. See "Alternating Currents" and "Radio F--quencies." FUSE.--A. small piece of wire or strip of definite material and gauge, and so resulated that it will melt if a current beyond a safe valve for the cireuit in yuestion is passed through it. The melting of the wire breaks the cirenit and stops the flow of current. GRID.--The control electrode of a threeelectrode valve, usually consisting of a piece of fine wire or mesh or helical coil of wire surrounding the filament. Potential changes of the grid cause magnified current variations in the anode Circuit. Due to the fact that current in the form of clouds of electrons (small particles of electricity) flows from the hot filament through the vacuum inside the Yalye, ta the plate, and there electrons

have to pass through the interstices of the grid, if the voltage applied to the grid is negutiye, the electronic current will be impeded in its flow. On the other hand, a positive potential will assist the flow. An alternating voltage such as ivailable from audio or radio frequeneies, will cuuse alternating negative and positive yoltuges, which will make the electronic current assume similar characteristies in a current form. By suitable adjusting the valye radio frequency may be cenyerted to audio frequeney. This action ts known us detection or rectification. The grid functions similarly in this case as a eontrol element. GRID CIRCUIE-The cireuit whieh externally connects the filament aud grid of a yalve, tind is completed internally by the electron stream between them. GRID CONDENSER.-A small condenser placed in the — grid ¢ireuit to assist the grid in rendeving the variations produced in the unode current unidirectional. Sonietimes a blecking condenser in the grid cireuit of a valve is termed no grid condenser for conyenience. See "Condenser Grid." GRID LEAK -A high resistance path connected between the gvid of na yalyve and the positive or negative of the lowfensiou battery, Placed in shunt acress the grid condenser it provides path or leak whereby the clectrous which collect on the grid may return to the filament. Without this leak the aceummulation of electro..s on the grid would interfere with receeption. GROUND.-An American. term = for earth connection, HARD VALYH.-A valve of which the containing glass bulb bas been exhausted ,to the highest possible degree. Nearly all English valves. and an. extensive range of American. are — hard. Some American "detector" yalyves are "soft," and can be used only for detecting purposes,