Communicating with submarines

Belconnen Radio Transmitting Station in Canberra was established in 1939 so that the Royal Australian Navy could transmit radio signals to ships in the Pacific and Indian Oceans.

Radio communication became very important between the First and Second World Wars as a way of communicating with ships around the globe.  The Royal Australian Navy needed to develop a facility to complement the Royal Navy’s communications station at Rugby, England, because the Royal Navy was unable to communicate with ships in the Pacific or Indian Oceans.

Aerial view of Belconnen Naval Transmitting Station. The transmitter building is at the lower left, and one of the three towers for the low-frequency aerial is immediately to its right. Photo courtesy of Eddy Mol.

In 1937, the Australian Government decided to erect transmitting and receiving stations in Canberra. Belconnen was selected for the transmitting station and Red Hill (later named Harman) for the receiving station.  The Station was officially established on 20 April 1939.

Gordon McDermott, former Officer-in-Charge at Belconnen, recalled in an oral history interview in 2007 just how important the station was.

Strategic importance: it was probably one of the most strategic, important communication assets in Australia, certainly for the RAN. It was the main means of communications between our ships and establishments, to other countries’ ships and establishments, so it was vital. It was the only way that we could actually talk to those ships, particularly when they were at sea and isolated from normal communications such as we know these days by mobile phones and satellite communications systems.”

The transmitter building in Belconnen, early 1940s. Photo courtesy of Eddy Mol.

The Transmitting Station proved to be highly effective. It provided good coverage over a very large proportion of the world’s oceans. Its signals could even be read by some RAN ships in the Mediterranean Sea! In 1947 the cruiser Australia was sent to Heard Island, in the Antarctic, to rescue the seriously ill station doctor who was suffering from acute appendicitis. The only way to communicate with the ship was to use Belconnen’s high power, low frequency transmitter, so normal transmissions were temporarily stopped to help with the emergency.

Global communication

Sending signals to submarines under water requires special equipment. Belconnen used a high power, low frequency (44 kHz) transmitter for omnidirectional transmission to ships and submarines.

Part of the controls for the 200kW low frequency transmitter, 1947. For scale, note the size of the door at the back right of the room. Photo courtesy of John Saywell.

John Saywell worked at Belconnen in the late 1940s as a Radio Mechanic. When I interviewed him, he explained how the low frequency transmission enabled communication with submarines:

The low-frequency equipment was used to provide worldwide communication and it worked in conjunction with the Rugby station in the UK to ensure that there was naval communication right round the globe. And it had another advantage, being low frequency, that submarines can communicate when they’re submerged to half a wavelength below the surface and the low frequency having a very long wavelength meant that the submarine could be quite well submerged and still able to communicate or receive messages.”

Generating the signals

The equipment required to send these signals was physically imposing. John Saywell described the massive transmitter:

[The low frequency transmitter] was the largest transmitter that I’ve ever come across. You could actually go in, walk in through the panels and walk in around the circuitry, and I’ve never experienced that in any other equipment at all. It was huge… And the output of that transmitter was fed through into what we call the ‘aerial tuning hut’, which was much more than a hut: it was a solid brick, reinforced, screened room, huge room, with huge aerial tuning coils in there and everything was large. And then the output from that was fed out to the feeder up to the antenna which was supported by three 600-foot masts and they were spaced at 1200 feet apart.

I was told a couple of stories there about the huge knife switch that you stepped up on a platform to operate, had initially built up so much corona on the right-angle edge that it shot through the concrete into the steel inside the wall and burnt a hole through the wall. The solution to that was to simply take a big file and round the corner off so that the corona was spread. And there was so much power leakage at the base of the central mast that it cracked the concrete there. It was what in present day terms you’d describe it as all being ‘awesome’.”

Part of the 200kW low frequency transmitter, 1947. Photo courtesy of John Saywell.

Part of communications history

Colin ‘Gabby’ Hayes worked at Belconnen in 1979-81, and described just how enormous the transmitter components were:

The LF transmitter actually is, I guess it’s a part of communications history. There’s not too many transmitters around these days where you actually have to open a door and walk inside it to check on capacitors and valves. I mean the size of the valves in that transmitter are the size of a small fridge, and the technology in those days was amazing; but you can get a microchip to do that stuff these days. So having a look inside that transmitter and the cabling and the helix room that connects it to the antenna is just something you will never get to see, or very rarely get to see, anywhere else in Australia.”

The trick with the fluoro tube

Those working at Belconnen remember a well-known party trick to impress visitors. Gabby Hayes explained:

We had some interesting stories about the LF transmitter, the 44 kilohertz transmitter. It was a 200-kilowatt transmitter so it put out quite a bit of power around the place. An example was the helix room which matched the impedance of the transmitter to the antenna. We used to walk in there and we’d have groups of school children or visitors come in to look at the station and our party trick was to get a fluoro tube and just hold it up in the air like Darth Vader and this fluoro tube would light up with the radiated RF from this helix and the kids used to think it was fantastic, you know. But if you did it these days you’d get shot, I think, for the OH&S concerns; but back in those days that was the thing we used to do.”

The inducted power from the low frequency aerial was so great that the neon tube in the hand of Officer-in-Charge Sub-Lieutenant Bill Williams glowed brightly, 1962. Photo courtesy of Bill Williams.

Balls of fire

The signals from the low frequency transmitter were sent using the enormous low-frequency aerial, supported on three 600-foot high towers.

Mike Witcher, who worked at Belconnen in the 1960s, kindly sent me his recollections:

The antenna for the low frequency transmitter consisted of three 600 foot high towers with heavy cables between them, another cable ran from the end towers towards the base of the central tower (half the length cable, half nylon rope)… The top of the antenna would sometimes be hit by lightning, or static electricity so that corona balls of fire appeared. One time, just as my crew were finishing our shift, a lightning strike caused one of the nylon ropes to burn through. The cable fell to the ground and shorted out feeder cables to many other antennae. About half of the transmitters, thus shut down. Great shift hand over!”

Three towers supported the low frequency aerial. Each week, the globes of the towers’ navigation lights were replaced by watch keepers and electrical artificers. For those who enjoyed the arduous climb, the views from the top were superb, and it was common to be asked to take photos with friends’ cameras. Photo courtesy of Eddy Mol.

Impressive lightning displays and molten concrete

Former Officer-in-Charge, Bill Williams, worked at Belconnen in the 1960s. He also recalled the spectacular effects of lightning on the towers:

During heavy thunderstorms, when there was lightning about, or when heavy cloud introduced a static charge on the existing antenna, there was very impressive display of arcing and lightning, on one occasion actually earthing down into the huge concrete base which these antennas, each mast stood on – and they were 600 feet high and weighed many, many tons – but this charge earthed down into the concrete base. The concrete actually melted and boiled, and there was an earthing strap adjacent to it which was melted, and the end result, when the concrete had finally set after all this performance ceased, was large chunks of boiled concrete interlaced with what had been molten copper. Very pretty pieces of rock, they were, but as I was the Officer-in-Charge of the station at the time I was absolutely horrified and petrified by all this because I had visions of the mast falling down.”

End of an era

The youngest sailor closing down the low frequency transmitter, Bels44, in 1995. Photo courtesy of Lionel ‘Pony’ Moore.

The low frequency transmitter kept Australia’s ships informed from 1939 until it was decommissioned in 1995. The towers that had been such an important part of Australia’s communication systems, and landmarks in Canberra, were demolished in 2006.

You can read more about the history of the Belconnen Naval Transmitting Station here.

Extract from oral history interviews with Colin ‘Gabby’ Hayes, Gordon McDermott, John Saywell, and Bill Williams used with the permission of the Australian Government Department of Defence.

Recollections of Mike Witcher used with his permission.

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