RADIO AND ITS RECEIVERS

Sun (Auckland), Volume III, Issue 735, 7 August 1929, Page 16

RADIO AND ITS RECEIVERS

Conducted for THE SUN b: WONDERFUL SET ATWATER-KENT’S LATEST SURPRISING RESULTS Jules Verne visualised many wonderful things long before they were actually invented, but even his fertile brain apparently failed to conjure, up the wonders of radio, and radio in its infancy certainly never visualised the Atwater-Kent scr.eened-grid allelectric radio set. Thanks to Frank Wiseman, Ltd., I have just had the opportunity of trying out this really remarkable set, and I must confess it has astonished me. The model supplied was a six-valve set, with rectifying valve and stepdown transformer, with an AtwaterKent dynamic loud speaker. The cabinet is a metal one, of handsome design, and the internal components are of first-class quality. It is exceedingly simple to operate, as there is only one tuning control, and one volume control. However, as the volume on the local station is too great using all the valves, a special cut-out is supplied, which brings down the volume to comfortable proportions. The tuning dial is illuminated. and one can tune in the dark. No batteries are required, and it is only necessary to plug in to the electric power. A.C. hum is practically inaudible.

Using an outside aerial, all the New Zealand and Australian stations, even the minor ones were heard at tremendous volume—in fact, Wellington and 2FC were so loud that the volume had to be reduced. The set is remarkably selective, and is one of the few that I have heard that will bring in 2BL Sydney when IYA Auckland is operating. To give some idea of the set’s singular selectivity, I found only two degrees difference between 2GB and 3YA, yet there was not the slightest interference between them. In daylig-ht, Wellington was nearly as loud as the local station. Using an indoor aerial consisting of an aerial tape round the picture rail, the results were even more remarkable, and I found that the stations heard with an outside aerial came in nearly as loud. It seems almost Incredible, but 2FC Sydney had to be reduced in volume for comfortable hearing. The loud speaker deserves special mention. It gives remarkably realistic reproduction, and even with the local station at full volume, though the sound is enormous, there is not the least blasting or distortion. A set such as this, requiring no batteries and no outside aerial, and giving such excellent results, is certain to attract many who have previously hesitated about taking up radio. RADIO IN CANADA The control of broadcasting in Canada is likely to be in the meltingpot in the near future, since a Federal Radio Investigation Committee has been appointed in Ottawa to go into the -whole question as to -whether broadcasting should continue under private ownership or whether the Dominion should follow the more or less government monopoly system as in this country.

The wire solderecfto test clips usually breaks off at the point shown in the above diagram. This may be prevented by soldering a short piece of bus bar wire to the under side the clip. The wire is then tightly wrapped with friction tape, which helps to keep the insulation from fraying and also provides a better grip. EXPERTS SAY Overloading the H.T. unit is one of the most prolific sources of annoying A.C. hum. It is a good rule never to draw from an eliminator more than about half or perhaps two-thirds of its rated current output. Always remove the H.T. negative plug from the H.T. ba.ttery before altering the wiring of the set in anyway.

Do not use ordinary 22 or 24 D.C.C. wire for battery leads, as the insulation is really insufficient for this purpose. .

The insulation of all battery leads should be absolutely faultless and above reproach, for it should be realised that they are a source of danger to the set if neglected.

AERIALISMS Grid choking is generally due to a faulty grid leak or to a faulty connection in the grid return circuit. The plates of an accumulator should not be exposed to the air. Faulty switches in the house lighting circuit will give rise to clicks and noises in the loud speaker, owing to sparking occurring across the defective points. Interference between neighbouring sets is not generally troublesome unless an unnecessarily large amount of reaction is used. If your programme is interfered with by your neighbour when adjusting his set, be sure not to share a common earth with him, but get a different earth, as this often makes a great improvement in such cases. If. you use an H.T. mains unit you should always switch this off when you switch the set off, and not rely on the on-off sw-itch of the set to break both circuits. Battery leads should always be regarded as potentially dangerous, and should therefore be of sound wire and of adequate size and strength. MIXED MELODY Unscheduled moaning heard during a recent “Memory Lane” broadcast in America caused timid listeners to look under chesterfields and beds for unseen company* Just as Eileen Piggott began her solo the moans commenced, continuing throughout the greater part of the number.

Operators in the control room began an investigation and discovered that in the studio of one of the stations broadcasting “Memory Lane” a microphone had been opened accidentally during a rehearsal of a mystery play, which was to go on the air in the following hour. Listeners thus heard two programmes at the same time.

. MURDER TRIAL BROADCAST 111 Mexico City arrangements were made to broadcast the proceedings of the trial of Jose Leon Toral, who has been accused of the assassination of General Obregon. This is probably the first time in which a murder trial has been broadcast by the State, and the step has been taken in view of the tremendous interest shown in the trial. Never attempt to make any adjustments inside a set with a metal screwdriver unless the H.T. negative plug is removed from the H.T. battery. Scores of valves have been burnt out in this way.

GRID-BIAS HINTS If ilie lid of a grid-bias battery i* turned upside down and screwed direct to the baseboard this will maka convenient stand in which the battery may be held in position on th» baseboard. In grid-bia.s batteries in which the lt-volt tapping is very close to the negative tap, the battery will be shorted if the plug is carelessly ad justed so that it will bridge the gap between these two. So care should be taken to avoid this.