190: Difference between revisions
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to the input. This interaction between is input impedance and gain measurements is | to the input. This interaction between is input impedance and gain measurements is | ||
often undesirable. Having a constant-amplitude source simplifies the measurement. | often undesirable. Having a constant-amplitude source simplifies the measurement. | ||
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Image:Tek 190b attenuator.jpg|190B attenuator | |||
Image:Tek 190b attenuator_entire.jpg|190B attenuator | |||
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Revision as of 06:54, 22 December 2010
The Tektronix Type 190A and 190B Constant-Amplitude Signal Generator is a sine wave source that uses feedback to provide a signal whose amplitude does not vary with frequency or with the impedance of the load, within stated limits. The frequency range is 350 kHz to 50 MHz. The amplitude measurement is made using a peak-to-peak (envelope) detector in an external attenuator head that is connected to the main unit by a special cable. The 190A uses a 6110 double diode tube for the detector. The 190B uses two 1N87A germanium diodes for the detector.
The 190 is useful for measuring the frequency response of a device whose input impedance varies with frequency. If a standard 50-ohm signal generator is used for this purpose, the frequency-domain variations of the input impedance of the device under test will result in frequency-domain variations in the actual signal voltage that is applied to the input. This interaction between is input impedance and gain measurements is often undesirable. Having a constant-amplitude source simplifies the measurement.
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190B attenuator
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190B attenuator
