......How do you transfer the accuracy from the SR-104 (10k) Resistor to the very low value resistors? I would like to measure some 0.1R resistors as accurate as I can do it. My reference are some VHP101 10k resistors.
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There are four other ways that I known of(apart from the way DiligentMinds.com introduced above) to transfer SR104-10k to 0.1R: the Hamon way, the modern DCC way, the old DCC way and the 3458A way.
In each way, there may be other resistors and equipment needed other than specified on the name.
In most of the ways, intermediate transfers may needed such as to 100R and 1R(R=Ohm).
The Hamon way
Equipment needed: 1k-per-step Hamon transfer standard, 10R-per-step Hamon and others(see notes)
Steps:
1. Connect 1k-per-step Hamon as 10k.
2. Compare SR104-10k and 10k Hamon(note 1).
3. Connect 1k-per-step Hamon as 100R and connect 10R-per-step Hamon as 100R.
4. Compare these two Hamons at 100R(note 2).
5. Connect 10R-per-step Hamon as 1R.
6. Compare this 1R with your target 0.1R(note 3).
Transfer uncertainty of less than 7ppm can be achieved.
The modern DCC way
Other equipment needed: 100R and 1R dummy standard resistors(notes 4)
Steps:
1. Compare SR104-10k with 100R dummy.
2. Compare 100R dummy with 1R dummy.
3. Compare 1R dummy with your target 0.1R.
Transfer uncertainty of less than 1ppm can be achieved.
The old DCC way
Old DCCs such as Guildline 9975 can only compare 10:1 resistor ratio in 0.1R to 10k range.
Dummy resistors needed: 1k, 100R, 10R and 1R.
There will be five steps to transfer 10k to 0.1R by using those dummies in succession.
Transfer uncertainty of less than 2ppm can be achieved.
The 3458A way
1. Calibrate the 3458A by SR104-10k(or make an ACAL, measure and record the difference).
2. Measure 0.1R by the 10R range of 3458A.
Measurement uncertainty of 100ppm can be achieved.
Note 1
There are many ways to compare two 10k either direct or substitute.
Below are the ways I may use(comparison uncertainty, estimate):
- 10k range of 3458A + automatic switch (0.3ppm)
- 10V range of 3458A + automatic switch + 20V voltage source mains powered(0.2ppm)
- 10V range of 3458A + automatic switch + 1mA current source battery powered (0.1ppm)
- 242D resistance bridge (0.2ppm)
- Guildline 9975 (0.2ppm)
- 10k Warshawsky bridge + automatic switch (0.1ppm)
Note 2
There are many ways to compare two 100R either direct or substitute.
Below are the ways I may use:
- 100R range of 3458A + automatic switch (0.5ppm)
- 1V range of 3458A + automatic switch + 2V voltage source (0.3ppm)
- 1V range of 3458A + automatic switch + 10mA current source (0.2ppm)
- 242D resistance bridge (0.2ppm)
- Guildline 9975 (0.2ppm)
Note 3
The comparison of 1R to 0R1 is more difficult, better to use a DCC(with constant voltage), or use constant current of 0.1A(or 1A, I have both) to run thru those resistors and measure the voltages across both resistors(by 3458A say).
Note 4
Resistors with large thermal mass and good TCR.