Glossary of Wireless Terms

Radio Record, Volume II, Issue 3, 3 August 1928, Page 63

Glossary of Wireless Terms

REE reer Irom week to week we give here a section of the glossary of wireless terms from the "Qistener’s Guide."

HENRY.-The ynit of self-inductance, being that inductance which will so retard any change in the value of a ecurrent that it takes 1 second for 1 volt to raise the current in a circuit by 1. ampere. In tuning circuits the Henry is too big,.and measyyements are usually reckoned in terms of milli- or micro-henries. HETERODYNE.-A. system for the reception of continuoys wave signals. he receiving circyit is artificially’ supplied with oscillations at a frequency slightly different from that of the incoming wares. ‘The two series of oscillatious alternately add and subtract ag they come into, or go out of, step with one another. This produces pulsations of amplitude at an gudible frequency, known as "beats." A. similar effect can sometimes be obseryed if twe adjacent notes on a piano are struck simyltaneously. HERTZIAN ‘WAVES.-Uleciro-mag-netic waves (the basis of radio transmission and reception), named after their discoverer, Professor Heinrich Hertz, ae

HIGH FREQUENCY (H.F.) OR RADIO FREQUENCY.-A term applied to alternations er waves which eccur at frequencies too high for audibility ; some- . times called "Radio Frequency." ILigh frequency may be taken to include all frequencies above 10,000 per second. HIGH FREQUENCY RHSISTANCE, ~The resistance which a conducting path offers to high frequency currents. Skin effect renders this higher than the resistance that would be offered by the same path to a continuous or low-frequeney current. ; Skin effect refers to the property of IEE, currents ef flowing on the outer edges of a conductor and not penetrating to the core. The higher the frequency the less the penetration. HIGH:TENSION (H.F.) OR "RB" BRATTERY.---The battery which supplies the enrrent flowing from the plate to the filament in. a radio valve. See B battery, ° HOWL.--A. symptom indicative of 2 state of oscillation in one er more valves at either high or-low frequency. High frequency ocsillation is usually indicated y a high-pitched whistle, whereas oscillation at lew frequency causes a lowpitched, loud howl. A howl due to either high or low frequency causes is due to necessity for readjustment of controls or servicing of receiver.