Hamon Transfer Standards
- LEEDS & NORTHRUP TYPE
- <0.01 PPM (THEORETICAL) ACCURACY FROM 1 Ω TO 10 KΩ
- FOR USE IN AIR OR OIL
- LOW TEMPERATURE COEFFICIENTS
- 10 Ω & 25 Ω COMMUTATOR OPTIONS
Ohm-Labs offers L&N 4321 and 4323 Hamon Transfer Standards. This pair of standards allows accurate transfer from the 1 Ω to the 10 kΩ level. The same construction can be supplied as a model 4322, with ten 100 ohm resistors.
The 100:1 ratio transfer accuracy of this standard has been calculated to be better than 0.01 ppm. Each Hamon contains ten nominally equal resistors permanently connected in series. A commutator connects the ten resistors in parallel, giving 1/100th the series resistance. Two optional commutators are available: One for a 1/10th ratio, and one for a 1/4th ratio to realize 25 or 2500 ohm values.
The internal resistors are wound from specially selected wire to provide matched temperature and power coefficients. The housing is hermetically sealed, providing isolation from changes in barometric pressure and relative humidity.
L&N Hamon Transfers use mercury cup connections on the top plate. There is no other connection type which provides equivalent repeatability and low resistance. The total quantity of mercury is estimated to be <2 grams, and chemically pure mercury is relatively non-hazardous, but appropriate care should be used.
Each 4321 10 ohm Hamon is provided with a matched parallel commutator which can be used with the 4323 1 K ohm model.
All Hamon Transfer Standards are supplied with resistor and node characterization as validation of ratio accuracy.
High resistance Hamon transfer standards are available in a guarded construction.
| Model | Parallel Resistance |
Series Resistance |
Series- Parallel |
| 4321 | 1 Ω | 100 Ω | 10 Ω, 25 Ω |
| 4322 | 10 Ω | 1 KΩ | 100 Ω, 250 Ω |
| 4323 | 100 Ω | 10 KΩ | 1 kΩ, 2.5 kΩ |
| Accessories | |||
| Part No. | Description | ||
| 169005 | Series-Parallel 10:1 Commutator | ||
| 169006 | Series-Parallel 25:1 Commutator | ||
Notes
- Temperature coefficients <10 ppm/°C (18-30 °C)
- Power coefficient <0.1 ppm/0.1 W (at 100 mW)
- 12-month stability is typically <2 ppm
- All resistance standards carry a five year warrantee
