By Chris Underwood
The next big project after the commissioning of Himatangi Radio was the detailed planning and building of a network of microwave links.
Site testing for the proposed links was undertaken by a specialist team from Radio Section, utilising local lines staff to assist with the erection of temporary guyed towers to permit height runs to be undertaken to check propagation paths.
Two towers were typically required for each hop to be tested. With the towers erected, two teams, comprising two technicians or radio engineers, undertook the tests with one team at each end. Normally two techs, one from Radio Section and one from the local radio depot, manned the transmit end while the party team leader, normally a Radio Section Radio Engineer, and a second technician from the local radio depot manned the receive end.
The tests comprised measuring signal levels with each dish antenna at different heights. Once the best height for each antenna was found, a longer term test was often run to confirm the viability of the path with the antennas at the set heights.
Years later, when I was involved in site testing, I soon learned that, while the planning team always did their site prospecting in nice summer weather, the site testing always seemed to be undertaken in mid-winter!
The first microwave system was installed in 1960 and used STC equipment employing Travelling Wave Tube technology. STC provided an instructor to teach local staff how to install and operate this equipment.
I never worked on the STC equipment but I understand an electric motor drove an AC generator plus the huge flywheel seen with its cover removed in the photo below. I’m not sure how the connection between the diesel and flywheel worked but my understanding is that if mains power was lost the flywheel would keep the alternator going until the diesel picked up the load of driving the alternator. I presume loss of power caused the diesel to start and when up to speed a clutch connected it to the flywheel. Can’t imagine the diesel was always rotating, with fuel shut off until needed and decompressors operating, but maybe a reader knows for sure?
More Land Mobile Service base stations were planned and built while existing ones were expanded to meet the increasing demand for service.
To assist in this work, new Radio Depots staffed with technicians were established, and to staff the new depots more trainee radio technicians were taken on.
All photos courtesy Chris Underwood (except where noted).
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