Broadcast - 10 August 2025
Last Wednesday’s Technical Night saw Idris VK7ZIR bringing in a pair of old plug-in modules, not just any old modules, these were Audio Programme Line amplifiers made by Trimax Australia circa 1969. In fact, they were programme line amplifiers that were located at the St. John telephone exchange in Launceston, dedicated to the carriage of audio from ABC Radio studios in Launceston to the ABC’s 7NT transmitters located at Kelso in Tasmania. These units provided isolation, matching, conditioning and amplification as well as a “Main” and “Standby or backup” path for the audio signal as it continued its long journey to the AM transmitters located at Kelso. Idris brought in these items of memorabilia to help celebrate 90 years of 7NT broadcasting in northern Tasmania.
These are not the original valve ones that were installed for the transmitter opening on the 3rd August 1935 but the next generation plug in transistorised modules that inevitable came along.
These were probably in service from the late sixties through to the transfer of 7NT from AM broadcasting at Kelso to FM broadcasting on Mt. Barrow in 2006. With it came the more common descriptor of “ABC Northern Tasmania” and there is now about sixteen relay transmitters throughout and covering Northern Tasmania.
The original AM main transmitter was 7 kilowatt with a 2 kilowatt standby. It initially broadcast on 710 kHz but changed to 711 kHz when the 9 kHz channel spacing was introduced. The original tower was 500 feet or 152 Metre tall, relatively soon after opening a second parasitic tower was added nearby to change the radiation lobe pattern to more of a figure 8, this was to minimise northern radiation and interference with Queensland stations.
Now for some interesting firsts and facts for 7NT and ABC Northern Tasmania:
It was opened by Tasmania’s first and possibly last contribution to Prime Ministers, The Rt. Hon. Joseph Lyons.
It was the first ABC regional station to be built and commissioned in Australia.
It was a relay station to 7ZL in Hobart.
It also relayed programmes from Sydney and Melbourne via a shortwave receiver until the installation of an undersea cable to Tasmania in 1936.
It was the first ABC regional station to broadcast local programmes in Australia.
A new purpose built ABC studio complex at Anne St. Launceston went to air in November 1972.
It still is the biggest ABC regional studio complex in Australia!
Now for all you PMG, Telecom, Telstra and ABC technicians, the Audio Programme Line amplifiers Serial and Item number is 238/30 and they still have the original post installation Dymo labels on them…. Sorry everybody else for this in house joke, HiHi
Now for all you budding health and safety representatives….. Just prior to 7NT being commissioned the word went out that any locals would be allowed to climb the 500 feet tower, if they wanted to!! Not sure about the safety equipment back in 1935, but what an offer and what an experience! Thank you, Idris, for bringing such nostalgic items in.
Bernie VK7BR also brought in a piece of history that might jog a few memories….. It was a Micronta Model 22-211 multimeter sold by Tandy Electronics last century and in surprisingly good condition. This is one of the few “Clam-shell” or folding multimeter styles that were made. When opened the bottom section housed all probe connection sockets and the 25 position range selector with the top section housing the 100 mm analogue meter. The amazing things are, it was actually a taught band meter movement and the scale incorporated a mirror for higher accuracy when reading, two quite surprising things to find on a cost effective meter from circa 1985. The meter movement is also shunt protected during transit, this is accomplished automatically every time the Multimeter is folded shut.
A bit of a clean and polish and it will look as good as new Bernie.
As always pictures will be available on the NTARC Web site under “Blogs” for this broadcast. NTARC Blogs
UPCOMING EVENTS
On Air Test and Technical Net session - Every Wednesday, Test-Net and CW course on 3.580 MHz from 7 pm, then a Technical Net on 3.567 MHz from 7.30 pm till 8.30 pm. Your host for the evening is Nic VK7WW.
Club Room Technical night session - The next session will be on Wednesday the 20th August and will commence at the usual time of 6.30 pm at the Club Room Archer Street, Rocherlea.
Coffee Morning - Held every Friday in the NTARC Club rooms. Time is from 10 am to noon.
Finally – If you have any items of news please email them to the Secretary at the following address news@ntarc.net all items to be received no later than 5 pm on the Friday prior to the Broadcast.
That’s all folks,
73, Stefan VK7ZSB
