History of wireless telegraphy and broadcasting in Australia/Topical/Publications/Australasian Radio World/Issues/1938 01

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Front Cover

The Australasian Radio World

JANUARY 1, 1938; Vol. 2 - No. 9; Price, 1/-

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

Cover Photo: Photo of Valve Ageing Rack at Philips Factory, Camperdown, Sydney (See Page 8)

Highlighted Contents: More about the Battery Amateur Communications Superhet: Power-Pack and Amplifier Unit for the A.C. "Empire All-Wave Three": Latest List of World Shortwave Stations

P.02 - Editorial Notes

Editorial Notes . . .

Nil

P.02 - Contents Banner

The Australasian Radio World

Incorporating the

All-Wave All-World DX News

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

Vol. 2. - January, 1938 - No. 9.

P.02 - Contents

CONTENTS:

"Empire" Power Pack And Amplifier . . . . 3

1938 Contest For Best Amateur Telegraphist . . . . 8

Breaking Into The Amateur Game (12) . . . . 10

Radio Ramblings . . . . 12

Radio Valves In The Making (1) . . . . 14

Schedule Of PCJ Experimental Transmissions . . . . 16

Twenty-Five Years In Amateur Radio (9) . . . . 18

World Shortwave Stations . . . . 19

Battery Amateur Communications Superhet . . . . 29

Eight-Valve T.R.F. Receiver Gives High Quality Output . . . . 36

National Field Day An Enjoyable Outing . . . . 38

What's New In Radio . . . . 41

All-Wave All-World DX News . . . . 43

Shortwave Review . . . . 44

DX News And Views . . . . 47

Australian Trained Radio Servicemen's Institute — Queensland Division . . . . 48

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 14th 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 Pty. Ltd., 214 George Street, Sydney, N.S.W., for the proprietors of the "Australasian Radio World," 214 George St., Sydney (Footnote P.48)

P.18 - Twenty-Five Years In Amateur Radio (9)

Twenty-Five Years In Amateur Radio . . . (9)

In this concluding instalment, the author discusses the relative merits of 5-metre aerial systems. He also gives details of further experiences in u.h.f. work, leading up to his establishment of a world DX record by putting 5-metre telephony signals into North Wales. By DON. B. KNOCK, Radio Editor, "The Bulletin."

BY the end of 1936, much progress had been made at VK2NO, with all kinds of directional aerial systems for 5-metre working, and at times some fearsome looking affairs sprouted around the shack, to the mystification of neighbouring residents.

From the original eight-wire beam with its "one-way traffic" limitations, arrays had passed through the stages of the twin radiator with reflector; twin dipole (end-fire) and Reinartz rotary, to the Bruce system.

There is little to choose between any of these types for local working (up to 100 miles) with the exception of the Bruce array. This system has already been described in "A.R.W." It has the highest gain of any in its simplest form of four half-waves in phase, and is bi-directional normally into the bargain. It is likely, however, to be a bit of a nuisance in windy weather unless one has adopted a very strong structural arrangement (which most hams don't do).

This system must be capable of 180-degree rotation with an accessible control, as the horizontal beam angle is around 15 degrees at 5 metres. Either side of that the signal falls off rapidly, both on transmission and reception. It is the best of the u.-s.-w. systems, in the writer's opinion, for those who want the best results.

The twin-dipole is very good. This is also for 180-degree rotation, but has a 45-degree angle and is end-fire. It is easily erected and rotated.

The simplest of all is the Reinartz rotary, being only 30 inches in diameter, but with a 45-degree angle in one direction. It must consequently be capable of 360 degrees rotation.

The system in use at the time of writing is a vertical W8JK "Flat-Top" beam. This has two full-waves out of phase with one-eighth wave spacing; is end-fire with about a 20-degree angle, and is a very convenient type for 180-degree rotation. This aerial is at present being tried out for possible overseas DX on 5 metres.

Atlantic Crossed On "Five" In 1926. The question of 5-metre DX has always been an interesting one to the writer, possibly because it is a tough nut to crack. The history of 5-metre communications shows that as far back as 1926, signals were sent across the Atlantic to Italy on 5 metres. There was never any two-way working in all instances of reported DX, and up to the present time such is still the case.

Late in 1936, the writer tackled the problem of advanced apparatus seriously, and a transmitter was designed using a 6L6 e.c. oscillator doubling from 10 to 5, driving a capacity-coupled RK25. This exciter unit was used to drive two Eimac 35T's in push-pull. The final stage would take a comfortable 150 watts input. Receivers were also tackled, and an eight-valve superhet with 5,000 k.c. i.f. channel was evolved.

The transmitter was tested out on various beam arrays, and for a considerable period the twin-dipole with 600-ohm line feed was employed, with a Reinartz rotary fed by twisted pair as a stand-by.

In the test days organised by W.I.A. (N.S.W. division) considerable success was obtained. The first surprise came when VK2DN, of Deniliquin, 360 miles distant, logged the i.c.w. test signals from VK2NO on schedule for a brief period, and this was followed by two-way contact during day and night with VK2ZC at Newcastle, 70 miles distant.

The biggest surprise of all came this year, when an ultra-shortwave observer in Pwllheli, North Wales, claimed to have heard telephony on 5 metres from VK2NO. Conjecture was rife, and doubts were freely expressed, but the hard facts turned up in the form of the log extracts of the signal, mailed from North Wales.

The interesting part of it is that VK2NO was at the time using the Reinartz rotary in communication with another Sydney station, and, furthermore, the signal had been heard but not identified on several occasions around that period by the North Welshman. This confirmation constitutes the world's record for transmission and reception on 5 metres, and now it is a matter of sticking at the job with earnest co-operation until two-way working is effected.

Regular Schedules With ON4AU. At the present time, schedules are being kept regularly with the well-known Belgian, ON4AU. He is using first-class equipment for c.w. transmission and reception on 56,080 k.c. ON4AU has 250 watts output with a beam array directed over the Great Circle route, and special W.E. u.-h.-f. valves are employed in the final transmitter stage. His receiver is a t.r.f. type using acorn valves.

In order to be fully up to the mark, the station at VK2NO has been re-modelled, and the transmitter now includes an extra buffer stage with two 801's in push-pull before the 35T's. The final has been re-designed for higher efficiency.

The most interesting part of the equipment is the new receiver for the combined job of straight c.w. and super-regenerative reception. Considerable work has been done with possible c.w. receivers previously, using standard valves, but the results had always been disappointing. Recently this new receiver was completed, and it uses a 956 acorn t.r.f. amplifier, 954 electron-coupled detector, EBC3 as interrupter when "supering" is wanted, and 41 audio.

A heterodyne oscillator has been incorporated, putting an old idea to modern use. This oscillator is at 20 metres, and the fourth harmonic is used to beat with the 954 detector, which can then be used in a non-oscillating but sensitive condition.

The method of operation is very simple. A c.w. signal is first tuned in with the detector oscillating (harmonics from c.c. stations on other bands are very useful for this), and then the beat oscillator is switched in and the detector regeneration backed of slightly. The result is a remarkably stable signal, with no loss of signal strength. The receiver handles on c.w. just as easily as if one were using it on 20 metres.

In use it has proved to be a revelation, and far superior to any receiver yet tried. Some idea of the efficiency can be gained when it is stated that c.w. harmonics of stations as far as 20 miles away can be heard at R7 on 5 metres when working on 20 and 10 metres. These results, however, appear to be obtainable only with valves such as the 956 and 954.

"Acorns" Well Worth While. "Acorns" are admittedly expensive, but despite their relatively high price, it is money well spent where it is a case of determination to get the best ultra-short-wave results. To spend money on the transmitter side and treat the receiver as an afterthought is less than half doing the job.

Apart from the primary interest to-day of ultra-short-wave experimentation, the writer does not completely neglect the ordinary routine of amateur communication, and may occasionally be found on 20-metre c.w. and 'phone, mostly in the early mornings, and very rarely on 40 metres.

In July this year, a considerable amount of 40-metre communication was obtained with the Mackay Aerial Survey Expedition in Central Australia, and this, being something different to the usual kind of communication normally to be had on 40 in these times, was an interesting interlude.

In conclusion, the writer would say that, despite the utility of modern radio-telephone communication, the telegraphy side is still as important as ever it was, and urges the amateur in general to strive to keep his hand in on the key. The reasons for such advice would take too much space, but they are numerous and indisputable.

Radio "Grandest Of Hobbies." After 25 years of experience in different forms with this yet infant science of radio communication, the writer considers that it is the grandest of hobbies for old and young, that if only the world at large could be made to realise it, amateur radio is a powerful weapon for world peace by intimate contact between fellow men; and that, progressive as radio is, it still has a long way to go. There is no end to its possibilities. (Conclusion).

Photo of 2NO 5 metre transmitter

The five-metre transmitter used by VK2NO. It put telephony signals into North Wales, and telegraphy across the Tasman to New Zealand, It has four stages, consisting of a 6L6 electron-coupled oscillator from 10 to 5 metres, capacity-coupled to an RK25. This exciter is linked to a buffer stage with two 801's in push-pull, and this in turn is linked to the final, using two Eimac 35T's in push-pull, with 150 watts input.