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The 218M modular control unit is coupled by a 2m long lead to the chopping head. Four easily-interchangeable chopping discs are provided as standard which allow chopping frequencies in the range of 0.5Hz to 3kHz.
A variable aperture 2-slot disc and higher frequency discs are also available. The chopping frequency is indicated by a digital indicating dial and a squarewave reference output suitable for use with lock-in amplifiers is provided.
Specification |
|
| Chopping frequency | 2-slot disc 5Hz - 200Hz |
| 5-slot disc: 12.5Hz - 500Hz | |
| 10-slot disc: 25Hz - 1kHz | |
| 30-slot disc: 75Hz - 3kHz | |
| Phase jitter: | 2-slot disc: 0.6° pk-pk over entire frequency range |
| 5, 10 and 30-slot disc: 1° pk-pk over entire frequency range | |
| Frequency selection: | By multi-turn potentiometer |
| Reference output: | 800mV positive-going wave from 200W. Sensed by IR LED/photodiode mounted on chopping head |
| Display: | LCD frequency display on free-standing controller turns counting dial on modular unit |
| External control: | The chopping frequency can be externally control via a front panel socket. Maximum input is = 15V into 20kW. |
| Resolution: | 1Hz with 10-slot disc |
| Motor | High quality 11-pole dc motor with precious metal commutator |
| Calibration accuracy: | ±1% for setting between 15% and 100% of full scale |
| Variable aperture: | A variable aperture 2-slot disc is available for non-even mark space modulation |
| Frequency stability: | Versus temperature: Less than 0.01% change per K Versus line voltage: Less than 0.01% change results from a change in line voltage from 190V to 265(95V to 130V) |
