One of devices which helps a lot during precision analog work is a decade resistors. In theory they are simple boxes with fixed resistors selected by decade rotary switches. While theory is simple,
devil is in details – resistors used are usually high-precision matched wirewound type, which have great stability and very low temperature coefficient. High-end decades were often used as resistance transfer standards for calibration and instrument checks. Today they are replaced mostly by calibrators, but for very top performance fixed resistance standards are still tool to have, such as ESI SR1010, and such.

Here we will study ESI DB52, which is low-end grade old 5-decade resistor, with maximum value 1111100 Ω, or 1.1111 MΩ.

Exterior and interior

Since I got 60% (3 from 5) of my 2001 meters repaired and ready for calibration, its time to get some resistance box. And as I already have some foils in main values, addition of more fine decade resistor was wanted.

I had no intention to spend big money, it is also my first ever decade box, so end up winning this ESI 5-decade resistor for a 95$ excluding shipping. Seller state it was good and calibrated January 2013.

It is dirty and little rusty outside, but that is fine if the thing performs well.

Don’t turn it on, take it apaaart :)

That is well and robust construction, but switches are not as fancy as in higher grade decades, which I saw on web review before.

There are no trimpots or jumpers elsewhere, how does such resistance decades are usually calibrated?

Performance and verification

I had two meters to check this DB52 :

Agilent 34970A with 34901A mux card, in 4W Ωs mode, 200NPLC (Calibrated in 2013)
Keithley 2001 , 4W Ωs with offset compensation, 10NPLC (Calibrated February 2014).

Below some key measurement thumbnails. Click to see original photo:

Measurement methodology far from perfect, just did as below

• First connect meter 4W to ESI decade. Set all decades to zero.
• Null meter using offset(relative) function. This will be our zero reference.
• Adjust decades, measure resistance.

4W Measurements data from 34970А

—	1E1	1E2	1E3	1E4	1E5
00	0.00007 Ω	0.00007 Ω	0.00038 Ω	0.02559 Ω	1.93515 Ω
01	10.00067 Ω	99.99229 Ω	999.93156 Ω	9999.91797 Ω	100001.12500 Ω
02	19.99982 Ω	200.00353 Ω	1999.89009 Ω	19999.94097 Ω	200016.91667 Ω
03	29.99740 Ω	300.00983 Ω	2999.82813 Ω	30000.11719 Ω	300011.90625 Ω
04	40.00387 Ω	400.01471 Ω	3999.79818 Ω	40000.22656 Ω	400014.12500 Ω
05	49.99859 Ω	500.02953 Ω	4999.77409 Ω	50000.20313 Ω	500017.66667 Ω
06	59.99515 Ω	600.03055 Ω	5999.70898 Ω	59999.72396 Ω	600026.75000 Ω
07	69.99643 Ω	700.03494 Ω	6999.64355 Ω	70000.16667 Ω	700028.00000 Ω
08	79.99512 Ω	800.04053 Ω	7999.60482 Ω	80000.16667 Ω	800028.50000 Ω
09	89.99380 Ω	900.04500 Ω	8999.57552 Ω	90000.13542 Ω	900032.16667 Ω
10	99.99229 Ω	999.93156 Ω	9999.91797 Ω	100001.12500 Ω	1000029.60000 Ω

—	1E1	1E2	1E3	1E4	1E5
00	Invalid data	Invalid data	Invalid data	Invalid data	Invalid data
01	67.043 ppm	-77.133 ppm	-68.420 ppm	-8.203 ppm	11.250 ppm
02	-8.965 ppm	17.624 ppm	-54.932 ppm	-2.930 ppm	84.609 ppm
03	-86.594 ppm	32.756 ppm	-57.292 ppm	3.906 ppm	39.688 ppm
04	96.703 ppm	36.774 ppm	-50.476 ppm	5.664 ppm	35.313 ppm
05	-28.305 ppm	59.082 ppm	-45.215 ppm	4.063 ppm	35.313 ppm
06	-80.808 ppm	50.964 ppm	-48.503 ppm	-4.622 ppm	44.583 ppm
07	-51.008 ppm	49.874 ppm	-50.921 ppm	2.344 ppm	40.000 ppm
08	-61.035 ppm	50.659 ppm	-49.377 ppm	2.051 ppm	35.625 ppm
09	-68.834 ppm	49.981 ppm	-47.201 ppm	1.476 ppm	35.764 ppm
10	-77.133 ppm	-68.420 ppm	-8.203 ppm	11.250 ppm	29.625 ppm

2W measurements from Keithley 2001

RAW data captured in CSV format

Value	Decade 10 [samples]	Decade 100 [samples]	Decade 1K [samples]	Decade 10K [samples]	Decade 100K [samples]
00	Invalid data	Invalid data	Invalid data	Invalid data	Invalid data
01	200.25 ppm . [ 16]	-21.36 ppm . [ 16]	39.18 ppm . [ 16]	-11.43 ppm . [ 16]	-14.63 ppm . [ 16]
02	24.10 ppm . [ 16]	6.31 ppm . [ 16]	-74.47 ppm . [ 16]	-5.28 ppm . [4690]	77.02 ppm . [ 16]
03	-90.84 ppm . [ 16]	22.04 ppm . [ 16]	-59.23 ppm . [ 16]	-11.64 ppm . [ 16]	68.42 ppm . [ 16]
04	146.45 ppm . [ 16]	28.01 ppm . [ 16]	-55.10 ppm . [ 16]	-8.06 ppm . [ 16]	67.97 ppm . [ 16]
05	-17.66 ppm . [ 16]	50.48 ppm . [ 16]	-50.82 ppm . [ 16]	-8.79 ppm . [ 16]	63.44 ppm . [ 16]
06	-55.95 ppm . [ 16]	42.95 ppm . [ 16]	-53.42 ppm . [ 16]	-17.35 ppm . [ 16]	72.18 ppm . [ 16]
07	-59.31 ppm . [ 16]	43.05 ppm . [ 16]	-56.06 ppm . [ 16]	-11.80 ppm . [ 16]	64.95 ppm . [ 16]
08	-63.33 ppm . [ 16]	44.74 ppm . [ 16]	-54.31 ppm . [ 16]	-12.69 ppm . [ 16]	57.51 ppm . [ 16]
09	-83.52 ppm . [ 16]	44.75 ppm . [ 16]	-51.91 ppm . [ 16]	-12.45 ppm . [ 16]	59.26 ppm . [ 16]
10	-21.36 ppm . [ 16]	39.18 ppm . [ 16]	-11.43 ppm . [ 16]	-14.63 ppm . [ 16]	56.62 ppm . [ 16]

Value	Decade 10 [samples]	Decade 100 [samples]	Decade 1K [samples]	Decade 10K [samples]	Decade 100K [samples]
00	Invalid data	Invalid data	Invalid data	Invalid data	Invalid data
01	10.00247349 Ω . [ 17]	99.99786425 Ω . [ 16]	1000.03918457 Ω . [ 16]	9999.88574219 Ω . [ 16]	99998.53710938 Ω . [ 16]
02	20.00048208 Ω . [ 16]	200.00126266 Ω . [ 16]	1999.85106659 Ω . [ 16]	19999.89438216 Ω . [4690]	200015.40429688 Ω . [ 16]
03	29.99727488 Ω . [ 16]	300.00661278 Ω . [ 16]	2999.82229614 Ω . [ 16]	29999.65087891 Ω . [ 16]	300020.52734375 Ω . [ 16]
04	40.00585818 Ω . [ 16]	400.01120377 Ω . [ 16]	3999.77960205 Ω . [ 16]	39999.67749023 Ω . [ 16]	400027.18750000 Ω . [ 16]
05	49.99911690 Ω . [ 16]	500.02523994 Ω . [ 16]	4999.74591064 Ω . [ 16]	49999.56030273 Ω . [ 16]	500031.71875000 Ω . [ 16]
06	59.99664307 Ω . [ 16]	600.02576828 Ω . [ 16]	5999.67950439 Ω . [ 16]	59998.95874023 Ω . [ 16]	600043.30859375 Ω . [ 16]
07	69.99584818 Ω . [ 16]	700.03013229 Ω . [ 16]	6999.60760498 Ω . [ 16]	69999.17431641 Ω . [ 16]	700045.46484375 Ω . [ 16]
08	79.99493361 Ω . [ 16]	800.03579330 Ω . [ 16]	7999.56555176 Ω . [ 16]	79998.98486328 Ω . [ 16]	800046.00781250 Ω . [ 16]
09	89.99248314 Ω . [ 16]	900.04027939 Ω . [ 16]	8999.53277588 Ω . [ 16]	89998.87988281 Ω . [ 16]	900053.33203125 Ω . [ 16]
10	99.99786425 Ω . [ 16]	1000.03918457 Ω . [ 16]	9999.88574219 Ω . [ 16]	99998.53710938 Ω . [ 16]	1000056.61718750 Ω . [ 16]