Himatangi 1951-1959

1951: Construction underway at Himatangi (see our photo collection)

Himatangi Radio. Undated. Photo: Foxton Historical Society

An early photo of Himatangi Radio, before the drive room was added in 1966. Photo: Foxton Historical Society

1953: Himatangi Radio opens

Himatangi Radio manager Jack Hogan (left) and Syd Thomson in front of the TBC-4 transmitter, c1953

Himatangi Radio manager Jack Hogan (left) and Syd Thomson in front of the 60kW GEC TBC-4 CW transmitter, c1953. NZ Freelance Collection, Alexander Turnbull Library

Syd Thompson and Gordon Campbell work on one of four STC DS-12 4.5kW transmitters. Johnny Morgan in the background.

Syd Thompson and Gordon Campbell work on one of four STC DS-12 4.5kW transmitters during the 1950s. Johnny Morgan in the background. Courtesy Jon Asmus. Click to enlarge.

Main control console at Himatangi Radio. Date unknown.

Main control console at Himatangi Radio. Date unknown. Courtesy Jon Asmus. Click to enlarge.

The Himatangi Radio control console was installed in a central position in the transmitting hall adjacent to the two London telephone and telegraph transmitters. It allowed the operating technician to gain instant access to the input line of each of the various transmitters as well as a sample of the radio frequency output from each transmitter – an essential feature when it came to circuit assessment or fault diagnosis.

The above photograph shows the control console manned by a technician on shift duty. The jack field and drop cords allowed him access to the input traffic line to each transmitter while the adjacent volume indicator showed the input level of signal from the particular remote traffic terminal.

The left hand units allowed a sample of the radio frequency output from each transmitter to be monitored for transmission quality and level. Two telephone dials allowed him access to the remote traffic terminals in Wellington and to the local PABX telephone exchange, while all circuit events were recorded in the station log book using world wide Greenwich Mean Time.

In the background can be seen the individual cabinets of the 50 kilowatt London telegraph transmitter.

George King

1958:

A transmitter was installed for the new radiotelegraph and telephone service to Vancouver. The Marconi HS51 had a rated output of 32 kilowatts PEP on single sideband. This transmitter occupied considerable floor area and required a separate automatic fire-protected sealed room to house its high current rectifiers and power transformers.

Assembling the Marconi HS51 transmitter

Assembling the Marconi HS51 transmitter. Courtesy Jon Asmus. Click to enlarge.

The completed Marconi HS51 transmitter with covers in place

The completed Marconi HS51 transmitter with covers in place. Courtesy Jon Asmus

Marconi HS51 transmitter in service

Marconi HS51 transmitter in service. Courtesy Jon Asmus. Click to enlarge.

A notable feature of the HS51 transmitter was the final output valve Marconi Type BR161. This impressive looking valve was a forced air-cooled triode fitted with a compact array of welded copper cooling fins and requiring forced air cooling at a volume of 20 cubic feet per minute. This air flow had to be started before the application of any supply voltage to the valve and continued for at least one minute after the supply voltages had been removed.

Himatangi technician Brian Gibb surveys the brilliant chrome of a BR161 RF amplifier valve (driver valves can be seen in the background). The two filament studs are evident at the top of the BR161, while the chromed upper heat sink provides the grid connection and the  cooling fins clamp with the carrying handles becomes the anode connection. The cost of a  Marconi BR161 valve to the New Zealand Post office was £450.

Himatangi technician Brian Gibb surveys the brilliant chrome of a BR161 RF amplifier valve (driver valves can be seen in the background). The two filament studs are evident at the top of the BR161, while the chromed upper heat sink provides the grid connection and the cooling fins clamp with the carrying handles becomes the anode connection. Information from George King. Photo courtesy Jon Asmus.

The operating conditions for the BR161 as an R.F. amplifier were as follows:
Filament voltage: 9 volts
Filament current: 175 amperes
Anode voltage: 12,000 Volts
Anode power: 15 kilowatts
Weight: 56 lb (26 kg)
Cost: £450
At no time during the switching on process was the filament current to exceed 450 amperes.

Information from George King

» 1960-1969