Siemens (Thomson) M273-A1 Kelvin measuring wiring tester (milliohm meter)

[Kiriakos GR]

This topic it is relative to Siemens (Thomson)  M273-A1 that is analog measuring  Low-Resistance device of 1983.

Siemens (Thomson) M273-A1 this is actually a resistors bridge this also using Thomson test leads connection which this is no other than more known Kelvin clips (four wires measurement).
This has three measuring ranges,  single knob at this device this is mechanical ranges selector, among push button (test start) and also this push button unlocks range selector when we need to move- up or to a lower range.

Accuracy specification this is 1.5% for it first measuring range that is from 200 micro-ohm up to 2.2 milliohm.
Other four higher ranges they are at 1% and measuring unit this is milliohm. 
2... 22 mΩ
20... 220 mΩ
200... 2200 mΩ

Specific made by Siemens meter, this using internal constant current source (circuit) so to inject DC current of 2A in to the test circuit.
This is a very high current which is designed to be used exclusively for wiring testing.
 
Practically Siemens (Thomson) M273-A1 this is first portable wiring testing meter which designed to serve in the application of troubleshooting telephone wiring connections at 1980 ~ 1990.

Picture of original test leads harness this is impossible to be found.
But even so,  my very own composed Kelvin clips to banana plug (test leads harness), this is not far away from what you do need as test leads for one M273-A1.

https://www.ittsb.eu/forum/index.php?topic=1314.0

[Kiriakos GR]

Siemens (Thomson) M273-A1  original stock pictures from Volos-Greece   
This meter belongs to a friend of my and by the use of my Galaxy S5  I did take some good pictures for the readers of ITTSB Blog.