The Fluke 752A has a 100:10:1 divider, and the lower sections are adjustable. This was done this way so that a (more or less) exact division ratio can be created. If the temperature in the lab changes a few degrees, you have to re-adjust it. There is another way to use this Hamon divider-- and that is with no adjustments. In this case, the ratios are *close* to 1:10 or 1:100, but maybe not exact, and that's OK-- as long as you *know* what the ratio *is* you can still use the divider to measure decade ratios.

This idea, I believe, is the winner.

After some weeks of researching the Datron 4902(S) and the Measurements International 8000B and the articles from the developers of the MI8000B, it looks to me that a mixture of these approaches may be very good for a DIY divider that can be used to rival the performance of the Fluke 752A and the 720A for use in a DIY home lab for precision divided voltages.

A stack of nominally accurate resistors that can be calibrated quickly and accurately every time the divider is used seems to me to be the most practical implementation.

Adjustment pots in the Datron 4902S and the switches in the MI8000B are the sources of difficulty and error.

What I do like is the procedure to perform an automated measurement of each element of the resistor stack before and after every use of the divider.

Here is what I am thinking of building

1. A 3-decade resistor stack. 10 pcs of 1K + 9 pcs of 10K + 9 pcs of 100k. No switches and no pots. Every step of every decade is brought out to a binding post for use as a calibrated voltage for a null meter connection. The top of the stack will be nomianally 1M ohm and calibrated at 1000V. So the voltages will span 1000V to 1V with 28 total cardinal points.

2. System for automated measurement of every position of every decade. This will be a Keithley DMM that accepts switch cards or a Keithley 7001 switch system. I own each and will have to find the correct switch cards to perform the switching and measurements. It will depend on the cost of the cards.

3. voltage sources for energizing the divider and for comparing the decade steps. Fluke 731B for the 10V and 1V step comparison voltages. Maybe the Fluke 332A for the 100V step comparison voltage. For divider energizing, maybe a Keithley 237. The model 237 can force current or can force voltage up to 1000VDC.

The idea is to use what I have in my lab now except for acquiring the correct switch cards.

This is all just paper design right now. Any suggestions are welcomed.