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Tellurometer

2025/005.2

Tellurometer MRA3 distance measurer

c.1970

SKU: 2025/005.2 Categories: , ,

Description

One of a pair of Tellurometer MRA3 distance measurers used by the donor in the early 1970’s as part of the British Antarctic Survey (BAS). The device is contained in a self-sealing and rain-proof metal case with a leather carrying handle. The control panel is accessed by removing the case’s back cover. A fitted framed haversack is used to transport the instrument. (See partner tellurometer 2025-005-1)

The tellurometer is a transistor instrument that is used for the accurate measurement of distances in surveying. To carry out a measurement, an instrument is positioned at each end of a line; by means of a switch, either instrument can be set to act as a Master unit and the other as a Remote unit. The instruments are capable of consistently measuring distances in excess of 50 (fifty) km. Under favourable conditions and subject to zero-error calibration, the overall measuring error is ± 1.5 cm ± 3 parts per million of the length being measured. For accurate results, it is necessary to take readings on a number of successive carrier frequencies in order to average out the effects of ground reflections, which cause the indicated readings to differ from the true readings. For long-range measurements, it is necessary to take accurate readings of atmospheric pressure, temperature, and humidity in order to calculate the refractive index of the atmosphere. For short-range measurements (below about 200 metres), calculation of the refractive index of the atmosphere is unnecessary.

The Tellurometer and other devices using microwave signals to measure distances revolutionised surveying by reducing the need for line-of-sight measurements over long distances.

The device is accompanied by:

  • Canvas fitted framed haversack
  • Tellurometer MRA3 Headset Assembly
  • Tellurometer MRA3 Battery Cable
  • Tellurometer Service Record
  • BAS Log Book for Tellurometer MRA3 Serial No 2356
  • Spare fuses (4 No)

The donor, Jonathan Walton, writes:

Ex British Antarctic Survey – used by myself in the early 1970’s. Last time I tried them, after they had been serviced, they worked. MRA3 is the rugged (militarised) version of the earlier Tellurometer 101. Tellurometer, a South African firm, made the first ever Electromagnetic Distance measuring kit which came out in about 1960. Enormous bulky machines but they revolutionised surveying. They were refined – the MRA3 was probably the most successful of all the models and relatively compact – would work from -40C to +40C (and I checked this out, at -45C they wouldn’t work! – these exact machines). They were serviced after BAS got rid of them … and I had them working – once.

The donation is also accompanied by:

  • Instruction Manual for the Operation and Maintenance of the Tellurometer MRA 3 MK II (December 1967)
  • Tellurometer Microwave System of Distance Measurement / MRA3 Dial Read-Out Operating Instructions (TI/T3/H) (x2)
  • “‘Micro-Distancer’ Model MRA3” Field Record pad
  • “CA1000 Field Record” pad

Additional information

Acquisition Number

2025/005.2
Item Type

Short Description

Tellurometer MRA3 distance measurer
Manufactured by

Date of Manufacture

c.1970
Sub-items

Various
Supporting Items

Various
Makers Number

2355
Marks

None
Dimensions (mm)

356 x 330 x 305. Weight 13.61 kg.
Donor

Date Donated

February 2025
Materials

Metals and glass
Condition

Good
Display Location

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