Tetrajunction

[VNUTDENYER]

Rather than bring back a dead thread, following concerning use of THREE tetrajunctions in a VERI (improved URS) may be of interest.

"Mounting a tetrajunction (a 1/2-inch diam copper sphere having four terminals).  A   composite junction consisting of three tetrajunctions,3 A, B, and C.   This is necessary because a junction may have a maximum of only four electrically symmetrical terminals [4]."   Hess, A. E., Nano·ohm junctions for accurate ratio instruments, NBS Report No. 9158 (Jan. 1966). FROM

 JOURNAL OF RESEARCH of the National Bureau of Standards-C. Enginee ring and Instrumentatio n Vol. 70C, No .  3, July-September 1966                 https://nvlpubs.nist.gov/nistpubs/jres/70C/jresv70Cn3p169_A1b.pdf
A Versatile Ratio Instrument for the High Ratio Comparison of Voltage or Resistance   Alfred E. Hess* Institute for Basic Standards, National Bureau of Standards, Boulder, Colo. (April 12 .  1966) 

A GOOD READ

[VNUTDENYER]

NIST way to make adjustable ratio divider with 11 tetrajunctions (triangle type) and 10 resistors
https://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote1297.pdf

EDIT:   WRONG DOCUMENT , thanks dieter, STILL LOOKING FOR IT

RE EDIT:  PAGE 34 IN https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=17477

 In a series of measurements using such transfer standards, the NIST OHM can  be  extended  in  multiple  decade  values  up to  10^10OHM.   Neither  the  absolute  accuracy  nor  long-term   stability   of  the   resistors   in  the  transfer   standards   have   any   effect   on  the   measurement accuracy.   The  concerns  with  the transfer  standards  are only  with  the  short-term   stability  required to  complete   the  measurements.
REAL GOOD READ