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067-0502-01: Difference between revisions
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The Tektronix 067-0502-01 is a instrument that can be used to produce a reference rectangle | The Tektronix 067-0502-01 is a instrument that can be used to produce a reference rectangle | ||
voltage or current waveform and/or to compare an external unknown input with an internal or | voltage or current waveform and/or to compare an external unknown input with an internal or | ||
external reference. The comparison if performed using an [[Airpax A175]] chopper | external reference. The comparison if performed using an [[Airpax A175]] chopper to switch | ||
between the two voltages that are being compared. The resulting output, a rectangular | |||
waveform with amplitude equal to the difference of two voltages, can be | |||
amplified and viewed on an oscilloscope. It is a well known and trusted technique, | amplified and viewed on an oscilloscope. It is a well known and trusted technique, | ||
the use of a chopper to make precise DC measurements using instruments that are sensitive | the use of a chopper to make precise DC measurements using instruments that are sensitive | ||
to AC, but not capable of drift-free DC performance. | to AC, but not capable of drift-free DC performance. | ||
The chopping | |||
technique can be used for calibration, comparing a device under test with a reference. | |||
In this case, the result of chopping is viewed on an oscilloscope oscilloscope, possibly | |||
with a preamplifier between the output of the chopper and the input of the oscilloscope. | |||
The operator adjusts the device under test to minimize the amplitude observed on the | |||
oscilloscope. The vertical sensitivity, DC accuracy, and DC drift performance of the | |||
oscilloscope and preamplifier are not critical if the goal is simply to calibrate the device | |||
under test for optimal match with reference. However, if the objective of the calibration | |||
is to provide assurance that the error is less than some specific value, then the gain of the | |||
preamplifier and oscilloscope matters. Still, the gain of the preamp and oscilloscope only affect the accuracy of the tolerance, | |||
which is typically around 10%, (e.g., +/- 0.01% or +/- 0.3%). | |||
* [http://w140.com/tek-067-0502-01.pdf Tektronix 067-0502-01 Manual (PDF)] | * [http://w140.com/tek-067-0502-01.pdf Tektronix 067-0502-01 Manual (PDF)] | ||