By temperature controlling an otherwise very stable resistor a performance close to the very best available World-wide can be achieved at a surprisingly low price. The resistor itself is oil filled and hermetically sealed.
The function of hermetic sealing is to eliminate the ingress of moisture and oxygen both of which play a role in the long term degradation of unsealed resistors. A further enhancement in both short and long term stability is achieved by oil filling. The oil also acts as a thermal conductor allowing the device to accept short periods of overload without degradation.
With accuracies of ±0.005%, a wide resistance range and long term drift of less than 5ppm, these devices are virtually secondary standards that can be kept in a laboratory as references to calibrate other devices.
The Resistor is held in a temperature controlled environment heated to 30°C ±0.1°C other temperatures are available to special order. The heater requires 2 watts at 5V which can be supplied by a battery or an unregulated DC supply. In an ambient of 20°C the Resistor’s heater will warm up in typically 30 minutes, and an LED shows when the temperature has been reached. A test pocket is provided so that the resistors’ temperature can be monitored if required.
Stability of 0.1 ppm/month or better can be expected. Standard models are: 10, 25, 100, 1000, 10,000Ω. For other values please contact Isotech.
For the highest quality traceability we recommend that the 456 be UKAS Certified. We can offer the 2 Sigma Uncertainties shown in the table.
|Stability||Typically 1ppm per year at 1mA|
10,000 Ohm 5ppm per year at 0.1mA
|Temperature Coefficient 10,000 Ohms||< 0.3ppm|
|Traceability||A Traceability certificate accompanies your 456 to the 2 sigma uncertainties shown.|
|Dimensions||114 x 110 x 96mm (in box)|
|Weight||1kg (including box) 550g (excluding box)|
|UKAS Calibration Uncertainty (Option)||12ppm|
|How to order||456 Temperature Controlled Fixed AC/DC Resistor. Please specify ohmic value. State with UKAS Calibration or without UKAS Calibration.|
Temperature Controlled Fixed Resistors
Nominal Temperature Coefficient of Resistance: +0.02ppm/°C (with temperature control on) 18 to 25°C
Model 456. By temperature controlling an otherwise very stable resistor a performance close to the very best available World-wide can be achieved at a surprisingly low price.
- Nominal Temperature Coefficient of Resistance: +0.02ppm/°C (with temperature control on) 18 to 25°C
- Power Rating: 0.5 Watt at +25°C
- Standard models: 10, 25, 100, 1000 and 10,000Ω
- Current Noise: <0.010µV (RMS) / Volt of Applied Voltage
- Thermal EMF: 0.1µV/°C Max; 0.05µV/°C Typical
- The most precise and stable resistors available
- Impervious to harmful environments - oil filled
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