History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1936 12

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Front Cover

The Australasian Radio World

Dec. 1, 1936; Vol. 1 - No. 8; Price, 1/-

Registered at the G.P.O., Sydney, for transmission by post as a periodical

Cover Photo: Mullard valves in kitset (See Page 7)

Highlighted Contents:

SPECIAL XMAS ISSUE: PARTY RADIO MAGIC: SCOUT BATTERY THREE:

HIGH FIDELITY AT LOW COST: FIVE-METRE SCHEDULES DURING

XMAS: LATEST SHORTWAVE NEWS: THE STORY OF TELEVISION.

P.02 - Editorial Notes

Editorial Notes . . .

The Power Interference Problem

The main bugbear of radio reception today is power interference, and it is an annoyance that is becoming more acute with the rapid growth of shortwave listening. Also, as far as reception of Australian stations is concerned, the effects of man-made static are intensified by the comparatively low transmitting powers used. The problem is one that will have to be tackled sooner or later, even if it means the passing of legislation to compel everyone operating electrical equipment that is giving offence to fit suitable filters to silence the noise. In this respect, concerted action on the part of the tramway and power supply authorities, who are among the biggest offenders, is long overdue. In England, thousands of pounds have been spent in the past few years on research into the problem, mainly by the Electrical Research Association with the assistance of the B.B.C., the postal authorities, and the Radio Manufacturers' Association. The subject has also been exhaustively analysed by various countries on the Continent, particularly by Germany, and as a result of all this research the causes of interference are now generally understood and suitable remedies can usually be applied. In a few cases the remedy is expensive, and so further research is now being undertaken to try and find methods of achieving the desired result more cheaply. The goal that has been set in England will be attained when, by a combination of suppressing equipment at the receiver and the fitting of filters to interference-creating equipment, radio reception for 90 to 95 per cent. of the listening public will be free from man-made interference. The same goal should also be the aim of the Australian authorities, but so far next to nothing has been done. The first, simplest, and cheapest step would be to increase station power considerably, to 'provide a better signal-to-noise ratio. The next and most important move is to have legislation passed that will render owners of interfering equipment liable to prosecution. The radio inspectors appointed by the P.M.G.'s Department are already doing splendid work in quelling interference, but until they have legislative backing their task is a hopeless one.

P.02 - Contents Banner

The Australasian Radio World

Incorporating The

All-Wave All-World DX News

Managing Editor - A. Earl Read, B.Sc.

Vol. 1. - DECEMBER, 1936 - No.8.

P.02 - Contents

CONTENTS:

Radio Gifts For Christmas . . . . 3

"Scout Battery Three" . . . . 6

Radio Ramblings . . . . 10

High Quality Reproduction At Low Cost . . . . 14

New £50,000 Factory Planned By Ever-Ready . . . . 16

The "Scout Superhet Four" . . . . 17

This Pentode Business (2) . . . . 22

The Story Of Television (1) . . . . 24

Radio Step By Step (5) . . . . 26

Party Radio Magic . . . . 28

The Cathode Ray Oscillograph At Work (4) . . . . 30

Radio In India . . . . 33

The A.T.R.S. Bulletin . . . . 34

What's New In Radio . . . . 36

Radio Book Reviews . . . . 37

Round The N.Z. "B" Stations . . . . 38

VK Amateur Stations — Additions And Amendments . . . . 40

All-Wave All-World DX News . . . . 41

Radio VK4DO Is Model Amateur Station . . . . 42

Schedules Of Japan's New Shortwave Service . . . . 42

Shortwave Stations Of The World (4) . . . . 43

DX Notes And News . . . . 45

P.02 - Publication Notes

The "Australasian Radio World" is published monthly by Trade Publications Proprietary, Ltd. Editorial offices, 214 George Street, Sydney, N.S.W. Telephone BW6577. Cable address: "Repress," Sydney. Advertisers please note that copy should reach office of publication by 15th of month preceding that specified for insertion.

Subscription rates: 1/- per copy, 10/6 per year (12 issues) post free to Australia and New Zealand. Subscribers in New Zealand can remit by Postal Note or Money Order.

Printed by Bridge Printery, 214 George Street, Sydney, N.S.W., for the proprietors of the "Australasian Radio World," 214 George St., Sydney (Footnote P.48)

P.38 - Round The N.Z. "B" Stations

Round the N.Z. "B" Stations . . .

1ZF . . . "Voice Of The Manawatu"

The first of a series of articles, written for the "Radio World" by a prominent New Zealand dxer. By "The SOUTHLANDER." ("The Southlander" was Merv Branks - Ed. Note) STATION 2ZF, Palmerston owned and operated by the Manawatu Radio Club. It has the distinction of being the oldest station on the air in New Zealand, and is now in its 13th year of broadcasting. The original call-sign was 2GI, and the first transmitter was battery-operated, a matter which caused considerable trouble and expense. Often listeners took turns to lend their "B" batteries, or there would have been no broadcast! Those were real pioneering days, when a wireless listener was looked upon as a crank. The Pick-up was not known in those days, and gramophone records were played on an ordinary gramophone into a telephone microphone, which was fitted with a cardboard horn to catch all the precious sounds. On The Air In 1924. The first listeners' meeting was held on July 9, 1924, at a time when there were only 38 radio sets in the city of Palmerston North. Everyone became a member of the Club, which was called the Palmerston North Radio Club. Today the receivers within a reasonable range of the transmitter number many thousands, as there is a population of 143,000 within a 50-mile radius. Immediately after this first meeting a five-watt transmitter was built and put into operation. About 1926 the licensing of broadcast stations came into force, and the club was allotted the call-sign of 2ZF, while its name was changed to the Manawatu Radio Club. Toward the end of the third year of operation one of the 50-watt valves blew out, which placed the club in serious financial difficulties. Debts totalled £97, but at the special meeting called to consider the position a committee was appointed to raise funds, as a result of its efforts £150 was collected in 10 days. Some Technical Details. The first transmitter in 1924 used a 210 as oscillator. Later a motor generator was purchased, and 50-watt De Forest valves were used. In 1928 a transmitter radiating 150 watts was built, and this did yeoman service for some years, when the whole transmitter was completely re-built, using crystal control, and a linear amplifier installed to give 250 watts unmodulated carrier. The present transmitter uses a 210 crystal oscillator, and two 865 screen-grid Radiotrons for buffers and amplifier stages, driving a 211 modulated oscillator. The first audio stage is also a 211, and the modulators are a pair of 845's in parallel, capable of modulating the class "C" oscillator to 100% without distortion. The final stage is a class "B" linear amplifier using four 250-watt Marconi valves in parallel pushpull, supplied from a three-phase full-wave mercury vapour rectifier outfit, giving 3,500 volts on the plates. This gives an unmodulated carrier of 250 watts to the aerial, which is an earthed Marconi "T" located on the roof of a two storey building. A cathode ray oscillograph is also part of the equipment at the station, and is used periodically to check adjustments of speech circuits, etc. The studio is large enough to accommodate an orchestra or band, while the announcers' room contains all the amplifiers, control panel, electric turn-tables, etc. The Club has a condenser microphone, one velocity type, and two double button carbon microphones. In addition to broadcasting their own programmes on Wednesdays, Fridays and Sundays at other times the Club relays the programmes from the National Station 2YA, Wellington, the programme being received over 100 miles of the Post and Telegraph Department landlines. First S.W. Re-Broadcast. One of the notable pioneering transmissions of 2ZF, occurred when PCJ was first picked up in New Zealand. The Club cabled the now famous station in Holland that their second transmission had been picked up, and they would like to hear England. In the next test transmission from PCJ, that station rebroadcast 2LO London and Daventry for the benefit of the Club, and then Paris and Langenberg, in Germany. The Club officials at 2ZF had secured the help of the local telegraph engineer for a relay line, picked up the transmission from PCJ, and rebroadcast the whole programme. The public was incredulous, and many considered it a first-class hoax! But it was a real thrill for the officials of 2ZF, as this was the first time that the public of New Zealand had heard England.

Photo Caption

(Start Photo Caption) The main studio of "B" class station 1ZF, Palmerston North — "Voice Of The Manawatu." (End Photo Caption)

Main Features Summary

MAIN FEATURES Call and Location: 2ZF, Messrs. Collinson and Cunninghame's Buildings, King Street, Palmerston North, New Zealand. Owners: Manawatu Radio Club. Frequency: 960 k.c., 312.3 metres. Power: 250 watts unmodulated carrier. Transmission Times: (E.A.S.T.), Mon., Thurs., Sat., 6.30-8.30 p.m.; Wed., Fri., Sun., 4.45-8.30 p.m. Area Served: 143,000 population within 50 mile radius. Longest Distance Verified Report: Honolulu, Los Angeles, New York.