History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1943 08

P.03 - Contents Banner
The Australasian Radio World

Devoted entirely to Technical Radio

and incorporating

All-Wave All-World DX News

Vol. 8. - AUGUST, 1943 - No. 3.

P.03 - Publication Notes
Proprietor - A. G. HULL

Technical Editor - J. W. Straede, B.Sc.

Short-wave Editor - L. J. Keast

Manager - Dudley L. Walter

Secretary - Miss E. M. Vincent

City Office - 243 Elizabeth St., Sydney - For all correspondence: Phone MA2325

Office Hours - Week-days: 10 a.m. - 5 p.m., Saturdays: 10 a.m. - 12 noon

Editorial Office - 117 Reservoir Street, Sydney

Subscription Rates - 6 issues 5/3, 12 issues 10/6, 24 issues £1, Post free to any address

Service Departments - Back Numbers, 1/- ea., post free; Reply-by-mail Queries, 1/- each

Printed by Bridge Printery Pty. Ltd., 117 Reservoir Street, Sydney, N.S.W., for the proprietor of the "Australasian Radio World," 117 Reservoir St., Sydney (Footnote P.28)

P.03 - Contents
CONTENTS:

CONSTRUCTIONAL -

Design for 20-Watt Amplifier. . . . 5

Test Panel for Vibrator Testing. . . . 7

TECHNICAL -

Common Errors of Amplifier Practice. . . . 11

The Measurement of Resistance. . . . 15

Headphones for Quality Reproduction. . . . 17

Radio Step by Step. . . . 18

SHORTWAVE SECTION -

Shortwave Review. . . . 21

Notes and Observations. . . . 22

New Stations. . . . 23

Allied and Neutral Countries Shortwave Schedules. . . . 24

THE SERVICE PAGES -

Answers. . . . 26

P.03 - Editorial Notes
Editorial

Recently l have accepted invitations to hear amplifiers and receivers which proud owners have considered to be the pinnacle of perfection. In nearly every case I have been sadly disappointed, and without regard to the rules of etiquette and hospitality I have felt it my duty to insist on the production of a meter to prove the most blatant faults, such as putting three watts of energising power into a speaker field coil and then feeding it with ten watts of audio. One of the amazing features of the human body is the way in which the senses will accommodate themselves to changed circumstances. They say that after working in a tannery, or other place where there is an obnoxious smell, the nose soon becomes accustomed to that smell and it no longer seems unpleasant. The ears have a similar characteristic. If you listen long enough to distorted reproduction you can eventually fool yourself into imagining that it doesn't sound too bad. The ear, being such an unreliable judge of distortion, we suggest that wherever possible a periodic check should be made with meters. Unfortunately it is not so easy to thoroughly check distortion with simple meters, but much can be done by indirect methods. If an amplifier is correctly designed and the valves and other components are in good condition, then it is unlikely that distortion will be present. We specially suggest the testing of valves, and checking such points as the actual wattage in the speaker field, the plate current of each valve, and measurement of the effective bias voltage between each grid and cathode.