THE MAGIC SPARK.

Auckland Star, Volume LV, Issue 75, 28 March 1924, Page 8

THE MAGIC SPARK.

. I NEWS OF THE WEEK. i AMPLIFICATION AND DISTORTION. WOMEN IN BROADCASTING. USEFUL TIPS FOR BEGINNERS. (By PHONOS.) Matters in connection with the proposed Auckland Radio Exhibition arc | moving apace. Mr. Andrews, a member of the A.R.A., leaves for Sydney to- ' day, and during a brief visit will I glean full particulars of the recent sue- j I cessful exhibition there, so that Auck- ' land may have the full benefit of Sydney's experience. The exhibition there, it may be noted, surpassed the most sanguine expectations of its supporters. ' The way in which radio enthusiasm grips one is well exemplified in the case of an Auckland amateur. Less than six months ago he started with a crystal set. Now he is a regular listener to Australia and America, and so keen is he that his motor car is now equipped t with a cage antenna, while the owner may be seen of a night driving, with phones on, and enjoying whatever his portable car set may pick up. The craze for fancy circuits, which at some stage of his experience attacks the average receiver, is now dying a natural death. The longing for auto- j dyne, oard, and other circuits is j becoming less pronounced, and radions i are again falling back on the old threecoil standard circuits with detector and two stages of amplification. For all practical purposes, beyond freak results, this type is asserting its general supe- , riority and utility. WOMEN'S OPINIONS RE BROADCASTING. An interesting subject has been opened up by the British Broadcasting Company, which has conducted investii gations concerning the type of broad- ' casting most desired by female listenersin. The question of what women want to hear is of interest to mere man, so that the experiences of the British Broadcasting Company in this direction are worth quoting. The company arranged for what was really a debate by radio; one of the speakers taking the side that what was really desired by women was " house- I hold talks," and the other expounding. that the lighter or social side should be' given more prominence- A vote on the , subject was called for, and so far themajority is distinctly against the house- ! wives. Perhaps the fact that the ' majority of those who have taken the trouble to write to the 8.8.C. are described as being of the " middle class " has something to do with this. " Please ask some of the women who really matter to come and talk to us about all i they are doing for the world, and keep us "in touch with the social things we cannot nowadays afford," is one wail— and the idea that " the social things we cannot afford" are the " things that ' really matter " is rather humorous, as also is the " Tell us about what they are doing on the Riviera and in Switzer- i land" which is the burden of another request. The letters so far received by the Broadcasting Company are being submitted to a committee of ladies, and . it is declared to be probabte that, while a certain number of domestic subjects will be retained, the remainder of the | " corner " will be devoted to a descrip- | tion of the " things that really matter " I so ardently desired by the majority of those who have expressed their opinions. DISTORTIONLESS AMPLIFICATION. The outstanding need of radio to-day, both , for the enjoyment of the art and to promote its further development as a sound industry is more efficient ampli- j fication. - I Not (only research 'engineers, but ; manufacturers, agree that the wider use of better amplification is the next stage of development of the utility. This will not only vastly increase the number of radio users, but immeasurably improve the standard and quality of results ob- j tamed in homes throughout the land. ' To be sure, amplification is already used with a vengeance. Vengeance is often the precise word. Too much of it sounds like an alley cat singing to its ! mate: "Last night on the back fence I j loved you best of all." J Radio's supreme need' is amplification ! without distortion. To amplify is easy, ' but to amplify so that no distortion or change in the sound is made requires careful design of the amplifier. In all amplifiers there are transformers and vacuum tubes. The transformer is the i heart of the amplifier. Unless the pro- i per transformer is used the singer's voice in one town is distorted into squeals ahd squawks in another. The voice will be amplified, but the tone and the rick j natural quality will not be preserved ' without a proper transformer. The general public is realising more ! every day that amplification is the most important single factor in radio. It i= j so fundamental that without amplification radio to-day would be impossible. Changing electric waves to sound waves . wouldn't mean much if they eoul-ln't be I heard plainly. Amplification guilds them up, so that they are clear and easy to I hear. Amplification is used at the transmitting station as well as at the ' receiving instrument. Faint whispers j thousands of miles away become clear, living- voices in the homes of millions. Amplification is multiplication Ths small amount of sound energy generated by the voice or violin string at the broadcasting station is changed to electrical energy and then multiplied or amplified millions of times. This large amount j of energy is then put into an antinna i and radiated out into space as an cl>i- I Iro-magnetic wave. When this wave ! i-trikes v similar antenna thousands cf ' miles away it gives'up to it a tmall j amount of this energy to bo amplified ■' again, so that a wliols room full t ,f : people at the remote point can listen and '■ understand. i In real and vital sense the key to radio . is amplification, and the publ.c ii i n .' ereasiugly realising this. Even more i important, they are demanding ampli- ! Ideation, whidPgivcs not only volume but ! : quality 01 sound—ampliation with.ut i distortion. A FEW POINTS FOB RADIONS. | In any type of regenerative set where j ' proper regeneration does not seem -to take place it is frequently advisable 10 reverse the wires which run to the tickler coil. This is particularly true of honeycomb roil «ets and other 'sets of a ■ similar nature. Adding more A batteries to your dry ! cell tube will not give you any louder signals. On the other 'hand it is far more apt to burn out the tube. Every ■

box containinfr a vacuum tube lias a printed sheet giving exact data on connection and A and B battery voltages. It is best to follow these exactly. Dry batteriea will have a preater life if they are kept in an upright position. In a radio frequency set it is highly important that the grid and plato wires be kept separate. If a tickler feed hack receiver regenerates too freely the capacity of the phone condenser should be reduced. Tn some instances 'a three circuit regenerative set can be improved by reversing the terminals of the plate : variometer. A 221 volt "B" battery should be I considered dead after its voltage drops . below 17 volts. j j The outside wire terminal ot secondary of an amplifying transformer: should always be connected to the grid of the tube. : minimum resistance an inductance should have a ratio of 2.46:1 between the diameter and the length. Placing a condenser in scrica with your aerial or sround. will materially reduce the wave length of your receiving set. If you cannot reach the higher waves on "your set this may be the cause. Place the condenser so that | one side is connected to the aerial and ! the other to the ground. Tins is a | parallel connection and will raiso the wave length range, of the <-et.