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"Wavescan" is a weekly program for long distance radio hobbyists produced by Dr. Adrian M. Peterson, Coordinator of International Relations for Adventist World Radio. AWR carries the program over many of its stations (including shortwave). Adrian Peterson is a highly regarded DXer and radio historian, and often includes features on radio history in his program. We are reproducing those features below, with Dr. Peterson's permission and assistance.
Wavescan N485, June 10, 2018
The Highest Powered Mediumwave Station in the Southern Hemisphere
Back in the era before World War 2, there were three mediumwave broadcasting stations that earned the title, The Highest Powered Mediumwave Station in the Southern Hemisphere. Two of these stations were located in country areas in Australia, and a third was located in a country area over in New Zealand.
Let's go back to the year 1931, and that was the year in which work was completed on the installation of a large and powerful mediumwave station in the Riverina, a highly productive and verdant agricultural area within the state of New South Wales. The primary coverage area for this new mediumwave station was the large twin cities of Albury-Wodonga and the surrounding country areas in the two states, New South Wales and Victoria.
The town of Corowa in New South Wales, together with Wahgunyah, its counterpart across the River Murray in Victoria, became an important upstream river port for the nearby goldfields back 150 years ago. This town, Corowa, played an important part in the events leading up to the Federation of the Commonwealth of Australia in 1901, with a decision that federation delegates should be voted in by the people, not by the colonial governments. The population of Corowa at the time when their radio station was installed was only around 2000 citizens.
This new mediumwave radio broadcasting station was installed on Honour Avenue (Riverina Highway, Hwy B58), three miles north of the town of Corowa and adjacent to the north bank of the meandering Murray River. Soil tests indicated that this area provided a suitable location for good mediumwave radio propagation.
This new mediumwave station in Corowa was allotted the callsign 2CO. It was intended as a regional relay station carrying the programs on landline from 3LO and 3AR in Melbourne, and it was installed on behalf of the recently organized Australian Broadcasting Company. Station 2CO was the third country relay station installed by the Australian Broadcasting Company since it was established just two years earlier. The two earlier ABCo relay stations were 2NC in Newcastle, New South Wales, and 4RK in Rockhampton, Queensland.
A new 7.5 kW STC transmitter was assembled in Sydney from imported parts, and it was installed in a new transmitter building specially designed and built for this important new radio station in Corowa. A special power line was run out to the station from the electricity generating plant operated by the local Municipal Council. For emergency purposes, a 150 horse power Gardiner generator was installed.
The operating channel for the new 2CO was given as 538 metres (560 kHz), which was the longest wavelength of any broadcasting station in Australia at the time. The power into the antenna system was 7.5 kW, which was described at the time as three times more powerful than any other radio station in Australia, and thus the highest powered radio station in the Southern Hemisphere.
The aerial system, quite unique, was suspended between two self-standing towers, 180 feet tall and 230 feet apart. There were six flat top wires, each 4 feet apart, and there were three downloads, each with a tuning coil in a small brick hut that led to an earthing pin. Each download was made up of four wires on a 4 inch circle.
This unusual aerial system, known technically as a Multiple Tuning System, was in reality three tuned antenna systems standing vertically, side-by-side. Each was connected electrically through the six flat top wires, and the radio frequency signal from the transmitter was fed through a download wire in the center of the flat top aerial system.
The earthing system was made up of seven miles of buried wire, arranged in a square pattern with transverse wires every three feet. The coverage pattern from this combined antenna and earthing system was ultimately quite circular.
A small soundproofed studio was installed in the main Post Office building in Albury, 30 miles distant, and Arthur Newnham was engaged as a part time employee to provide local news and information for occasional broadcast over 2CO. The Chief Engineer for the station lived in a dwelling that was constructed on the station site.
The official inauguration ceremony for the new 2CO was staged on the ground floor of the two story Memorial Hall, the Literary Institute Building, at 51 Sanger Street in Corowa, on the evening of Wednesday, December 16, 1931. This building is these days the Information Centre for visitors coming into Corowa.
The opening ceremony was made up of speeches, local live music, and recorded music. The entire program was landlined to 3LO in Melbourne and 2FC in Sydney for live rebroadcast. The inaugural live concert was performed by the ABC Orchestra from 3LO in Melbourne, who traveled to Corowa for the occasion.
The two main speeches were presented by Mr. Stewart Doyle, who was Chairman of Directors for the Australian Broadcasting Company, and Mr. H. P. Brown, who was the Director of Posts and Telegraphs in the Federal Government. The name of Mr. H. P. Brown is remembered as the official government name on ABC QSL cards from that time period. During the official ceremony, it was announced that another similar high powered radio broadcasting station was under construction near Port Pirie in South Australia.
These days, the ABC regional station at Corowa is still on the air, with 10 kW on the modified 9 kHz spacing channel 675 kHz, though still under the same callsign 2CO. However, the highest powered stations in Australia are now ABC stations at 50 kW, of which there are just thirteen throughout the continent. The highest powered non-government (commercial) radio broadcasting station in Australia these days is listed with 17 kW, and there is only one at this power level; 4BC Brisbane, 1116 kHz.
So what about that other high powered station that was mentioned during the inauguration of 2CO? Well that one became 5CK and we will cover that story in a few weeks time here in Wavescan.