RF - Longwave

This page reviews the early development of radio services in New Zealand amid the international issues of the times. The main focus of this review is 'longwave', the radio frequency (RF) range used by spark transmitters.

Telefunken and Marconi

When radio was first available commercially, Telefunken was a major company worldwide in the installation of radio telegraph stations, their main competitor being the Marconi Company. On 27 June 1912 a newspaper report advised that there were 3000 wireless telegraph stations installed worldwide. Of these, 1260 were built by Telefunken, 229 were owned by Germany and 159 were owned by the United States.

At an Imperial Conference in Melbourne in 1909 Australia undertook to build two high power radio telegraph stations, one at Pennant Hills, Sydney and the other at Applecross, Perth and New Zealand undertook to build two similar stations, one at Doubtless Bay near Kaitaia and one near Bluff. In 1910 New Zealand called for tenders and accepted the bid by Telefunken through their agents, Australasian Wireless Limited. The tender called for two high power stations (Awanui and Awarua) and five low power stations (Auckland, Wellington, Chatham Islands, the Government steamship Tutanekai and a fifth as standby or spare parts as required). On 9 December 1910 the contract was confirmed by payment of 300 pound from the Minister of Telegraphs in Wellington to Australasian Wireless Ltd in Sydney.

In 1912 while building of the New Zealand radio stations was in progress, the Marconi Company's managing director, Godfrey Isaacs, sued Telefunken for infringing one of their patents, a charge which Telefunken conceded. On similar grounds Isaacs sued the governments of Australia and New Zealand together with the Telefunken subsidiary contracted by them to build coastal stations. Again defeated, Telefunken was reduced to a taking a minor partnership in a new Marconi-controlled monopoly, Amalgamated Wireless (Australasia) Limited (AWA Limited).

Regardless of these events, construction of the sites proceeded. The first New Zealand site was opened on 26 July 1911 with a 2.5 KW spark transmitter operating from a tower on top of the General Post Office in Wellington. In October of 1911 when a purpose-built facility had been completed at Mount Etako, Tinakori Hills the equipment was relocated from the GPO to this higher site. The stations at Awanui and Awarua were to the same design, a key feature being a massive 60 ton triangular steel lattice tower 394 feet (120m) tall and 9 feet (2.7m) across the sides. The construction of both masts was overseen by a Telefunken engineer Herr Reinhardt who was well respected for performing this role around the world. Awanui was operating from 27 March 1913, but both Awanui and Awarua radio stations were formally opened for business on 18 December 1913.

By this time the war clouds were building over Europe and the German members of the construction team were eager to complete all southern hemisphere construction and return home. Britain declared war on Germany on 4 August 1914 and that news was announced in New Zealand on 5 August. On 6 August the British informed the New Zealand Government that the capture of German Samoa and control of its Telefunken-constructed radio station would be a 'great and urgent Imperial service' and on 29 August New Zealand completed that task without a shot being fired.  However, the Apia radio station generator had been sabotaged and the flywheel flew to pieces when the generator was started. A spare flywheel was sent up from Awarua Radio to get the station functioning again.

The British placed a similar request on the Australian Government regarding German radio stations on and near German New Guinea. Australian forces subsequently took control of stations at Nauru and Rabaul in New Britain. Britain's ally Japan seized the German colonies of Marianas, Palau, Caroline and Marshall Islands.

Advances in Radio Communications

While the Telefunken 'singing spark' system ordered by New Zealand in 1910 was based on a stable and capable technology, the field of radio was rapidly changing and new advances had already made spark technology obsolete. For instance Canadian inventor Reginald Fessenden had notable achievements of the first audio transmission by radio (1900), the first two-way trans-atlantic radio transmission (1906) and the first radio broadcast of entertainment and music (1906). US inventor Lee DeForest had patents approved for directional antenna (1904), a vacuum tube detector diode (1906), separate transmitting and receiving antennas (1906) and for an amplifying triode valve (1908).

The biggest pitfall of spark technology was the broad spectrum used by each transmitter. With no effective tuned frequency, spark transmissions blotted out the band. Therefore, where radio stations were located within range of each other they were forced to take turn about using the airwaves. Gentleman’s rules applied, except that the station with the highest power inevitably had right of way.

Thermionic Valve

The thermionic valve provided a major step forward for radio. It allowed the amplification of weak signals at receivers, and when feedback and tuning was added created a stable radio frequency oscillator source for transmitters. The concept of radio frequency allocation was born, allowing multiple stations to transmit simultaneously on separate frequencies without interfering with each other.

With control of transmitter frequency available, wireless development continued though still focused on high power, longwave (low frequency) systems. In 1913 the British government let a contract to the Marconi Company to create a longwave 'chain of Imperial wireless stations' - a contract which was suspended because of the outbreak of the Great War - WWI. Thus Britain entered that war strongly reliant on its cable networks while rapidly cutting any of Germany's cable systems or taking over its radio stations in vulnerable places. Kaiser Wilhelm II was able to use most of his already established network of longwave wireless stations to communicate and would retaliate by cutting British cables in the Pacific.

In July 1922 the Britain government announced it would build a longwave station at Rugby. This station was to operate at the VLF (very low frequency) of 16kc/s (kHz) and would use twelve 820 foot (250 metre) tall masts. The station eventually entered service and its tall masts remained a key feature on the regional skyline between 1926 and 2007.

The End of the Spark Era

In 1926 the US authorities prohibited the use of spark transmitters by its amateur radio enthusiasts. However, the big 'nail in the coffin' for the demise of spark transmissions occurred at the 1927 International Radio Telegraph Convention of Washington where it was agreed that:

  • The use of damped wave trains (spark transmitter emissions) below 375 kc/s be forbidden from 1 January 1930;
  • No new spark transmitting installations to be fitted in a land or fixed station, shore stations being prohibited from using damped waves from 1 January 1935;
  • No new spark transmitting installations be fitted in ships or aircraft from 1 January 1930 (unless their full power is less than 300 watts input power); and
  • Use of spark transmission on all frequencies be forbidden from 1 January 1940 (except for low power emergency ship installations).

In New Zealand the high power spark transmitting station at Awanui closed down on 10 February 1930, its services transferred to ZLD Auckland where a low power spark service had been installed in 1912 on the roof of the Auckland Chief Post Office. ZLD would have been permitted to use its spark transmitter up to 1935, but would have moved to using shortwave equipment after this time and for its subsequent transfer of location to Auckland's new Musick Memorial Radio Station in 1940. Likewise, Awarua's spark services would have ended by 1 January 1935 at the latest in compliance with the international agreement of 1927.

By 1940 spark transmission had ceased to exist - except that it hadn't! There was still the loophole left by bullet-point 4 of the 1927 agreement. Taking advantage of that little gem, a British Post Office handbook of 1954 noted that spark transmission was still permitted on 500 kc/s as an emergency signalling reserve for ships and lifeboats!