RADIO NOTES

Rotorua Morning Post, Volume 1, Issue 49, 20 October 1931, Page 5

RADIO NOTES

"Kathode,"

By

During the International Programme at 1YA this evening, Dr. E. B. Gunson, President of the Auckland Society of Arts, will speak on. "The International Outlook on Art."The programme from 2YA to-night will beof'the po'pular type.' " The Salon Orchestra will be hard in "Gtybrille'Su'ite," "Qoncertp for Clarionet and Orchestra," "Canzpnetta," "Enfant Prodigue" and the selection "Maid of the East." The Harmony Four, a novelty instrumental and vocal quartette, will render up-to-date. melodies. The vocalists will be Miss Phyllis Leighton (mezzo-soprano) and Mr. A. W. beckford (baritone) . The St. Kilda Band and assisting artists will provide the programme from 4YA. The Harmonists,' a 'mixed quartette, will sing concerted numbers and solos will be provided by Miss Mae Matheson (soprano), Miss Margaret Green (contralto) and Mr. C. S. Hawes (baritone). A concert solo will be rendered by Bandsman Ghristie and Mr. Ted Heaney will provide piano-accordeon items. 3YA will observe the usual silent night. ' '• Conditions during the past week have been good, both for local and trans-Tasman reception, though fading has been noticeable occasionallj''. The Australian stations have been coming over with excellent strength, and even the low powered B elass transmitters have been logged at loud speak er volume. The lower end of the broadcast band, between 300 and 200 metres, was over-erbwded and 18 stations were identified on'e evening, transmitting on that part of the spectrum. Many others were heard but were too badly hetrodyned to log. 2FC still holds pride of place and is frequently heard supplying programmes to four or five other Australian stations. The theme-song type of programme mentioned in the last notes appears to be a feature at this station every Tuesday night. The value of good tone in a receiver cannot be over-emphasised. Listen carefully for the treble notes. They should be perf ectly clear and brilliant. The lower registers, too, should be present, though a preponderance of bass makes the music beavy and dull, which may seem pleasing at first, but will soon beeome wearying. It is a mistake to purchase a receiver without having first of all made sure the tone will please you. There seems to be a strong belief among constructors that all leads should be kept as short as possible in a receiver. Short leads certainly have their place in a set, but there are some leads that must not be made too short. For instance, take a variable condenser and a coil in a tuned cireuit. Within this circuit, the current oscillates back and forth at resonant frequency, meeting with no opposition except from the resistance of the circuit. Consequently, if we have gone to the trouble to produce a good coil and have purchased a good condenser, it is important that as little resistance as possible must be added to the circuit, otherwise little will be achieved. We can effectively add resistance to the tuned circuit by placing the coil close enough to the condensed to set up eddy currents, buf as resistance is undesirable, these leads must be long enough to prevent the field about the coil setting up such currents. The writer had experienee with this problem while experimenting with a short wave transmitter, a few yearS ago. Considerable pains were taken to make a neat job of the set, and short leads certainly lend thefaselves to neatness. When put on the air, the transmitter functioned fairly well on 80 metres, but the power was considerably reduced on 40 metres and the set refused to oscillate on 20. Investigation showed that the resistance produced by eddy currents was high enough to prevent proper oscillation and the transmitter functioned perf ectly after the coil had been moved out another two inches from the condenser.

The ordinary listener usually looks upon radio as being something pecuculiar and mysterious and having no connection wtih ordinary things. Radio is no m;ore mysterious than light, heat, X-ray and other things we treat as ordinary. Radio vibrations are tbe same in character as ligbt and heat, and differ only in frequency. The 64 octaves of electromagnetic waves include X-ray, light, heat and radio in order of frequency, and are all subject to the same laws. They are all vibratory wave motion*. The electrical rule laid down a$ Ohm's law states: "Electric current is equal to the electromotive force, divided by the resistance." Set down mathematically, this is, I equals E/R, which may appear difficult to those not conversant with electricity and radio, but the same rule may be translated into: Result equals Fffort divided by Opposition. And so we could go on peeping behind the curtain that has shrouded radio for so many years. ,We do not regard light as being mysterious because we can see it, nor do we regard heat as mysterious, because we can feel it, but when we remember that radio is similar to both, except that it can neither be seen nor felt, we will cease to regard it as being beyond our comprehension. The statement that radio waves cannot be felt is not altogether true, as under special conditions they can be felt as heat (some transmitters have had painful experiences of this) though one must be close to the source of propagation to experienee it. The all-electric set has many advantages ovet the battery operated type. Greater power can be supplied to the a.c. valve, gaving higher amplification and better tone. Constant checking up of batteries is no ionger necessary and the modern a.c. receiver is simplicity itself.