This is DN Calling

NZART historian Craig Crawford ZL3TLB contacted me regarding the centenary of Radio Broadcasting in New Zealand and asked how we were going to celebrate. This prompted some interesting research.

Otago has had a fair share of early wireless pioneers. In 1902 sixteen year old James Passmore built a spark transmitter and coherer receiver to communicate over 100-200 metres. By the following year he had increased this distance to 10km, communicating between Flagstaff Dunedin and Outram.

In 1908 a trio of teenagers; Rawson Stark, Cyril Brandon and Stanton Hicks, successfully transmitted messages across the Otago Harbour from Andersons Bay to Ravensbourne. While this was only a few kms they received great publicity by transmitting messages between the Mayor of Dunedin and the Mayor of West Harbour. They also transmitted a message from the Dunedin Mayor which was forwarded by telegraph to Prime Minister Joseph Ward.

However, Radio Broadcasting was to come much later. In 1921 University of Otago Physics Professor Robert Jack sought permission from the government to begin experimental Radio Broadcast transmissions. Professor Jack was convinced that Radio Broadcasting of information and entertainment had the potential to “End the isolation of New Zealand and rural New Zealanders”.

Professor Jack’s initial requests were turned down but finally he received permission. On 17th November 1921 he began transmitting. Broadcasts consisted of announcements, gramophone recordings and live music (some of which was performed by Professor Jack’s wife, Isabella).

Professor Jack’s broadcasts continued two nights a week. Reception reports were received from all over New Zealand. The broadcasts ended in May 1922 by which time they had inspired many. From this the “Otago Radio Association” was formed and began its own broadcasting in October 1922.

The Otago Radio Association has changed callsigns over the years but remains on air now broadcasting as “Radio Dunedin”. It is regarded as the 5th oldest radio station in the world, and the oldest outside of USA.

It appears that Professor Jack’s station was never issued with a callsign. The idea of callsigns for broadcasting stations was not something thought of at the time. When the initial broadcasts of the Otago Radio Association began, announcers used the phrase “This is DN calling” to identify the station, although it seems unlikely that DN was ever an official callsign. Eventually the Otago Association was issued with the callsign 4AB. This was replaced with 4ZB (not the later government station) and then to 4XD in 1948.

It is interesting reading old Radio Callbooks of the late 20s and early 30s. There were a surprising number of Broadcast Stations. Many running 10‑20 Watts into wire antennas strung between buildings.   They usually ran for only one or two nights per week. Most ran from stores selling radios and/or gramophone records. A single frequency was shared by stations transmitting on different nights of the week. The Otago Radio Association was a non‑commercial voluntarily run station and was allowed to continue when other non-government stations were closed down. It ran this way until 1990 before finally becoming a commercial station.

In order to celebrate the centenary of Professor Jack’s original broadcasts, Otago Branch 30 has obtained the special callsign ZL100DN and will run a “DN Calling Award” over the month of November. Listen out for ZL100DN and other Branch 30 stations during the month of November on 3610 kilocycles +/- QRM.

David Mulder ZL4DK

[more details of the Award will be released as they are finalised]

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