Nautel NTT4000 transmitter

  • Manufacturer: Nautical Electronic Laboratories Limited, Hacketts Cove, Halifax County, Nova Scotia, Canada
  • Type Number: NEL7203
  • Power output: 1000 watts continuous, 4000 watts PEP
  • Mode: A1, A2 (Modulated CW), A2H, A3 (AM)
  • Frequency Range: 400-535 kHz (was used on 487.5, 500 and 512 kHz at ZLD)
  • Power Requirements: 230V 50-60~, single phase
  • Status: Operational on 512 kHz, not currently in service as ZL1ZLD is no longer authorised to use this frequency
Front panel layout of the Nautel NEL7203 marine transmitter.
Front panel layout of the Nautel NEL7203 marine transmitter. Source: Nautel Instruction Manual, p 1.3

This totally solid-state transmitter was used at Auckland Radio ZLD until the station closed in 1993.

Its modular design allows any of the 16 power supply or 16 power amplifier modules to fail, or be removed for servicing, while the transmitter remains on the air.

The transmitter is set for operation on 487.5 kHz (Auckland Radio’s working channel), 500 kHz (marine distress and calling channel) and 512 kHz.

512 kHz was an original ZLD frequency, and was used by ZL1ZLD, the amateur radio station at Musick Point, until mid 2013 when amateurs were allocated a new 630 metre band (427-479 kHz).

Nautel marine radio transmitter
The Nautel 500 kc/s marine radio transmitter before it was removed from the Oliver Road transmitter site in 1993
Rescuing a Nautel transmitter
Members of Musick Point Radio Group rescuing the 500 kc/s Nautel transmitter from the Auckland Radio Oliver Road transmitter site before it was demolished.
Nautel marine radio transmitter
Nautel marine radio transmitter after moving to Musick Memorial Radio Station, ready for cleaning

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