191
The Tektronix Type 191 Constant Amplitude Signal Generator is a sine wave source introduced in 1966. It covers frequencies from 350 kHz to 100 MHz in seven bands. The output amplitude can be adjusted in calibrated steps from 5 mV to 5 V in three ranges. The oscillator is an Colpitts oscillator using a 7119 tube. A peak-to-peak detector made with two GaAs diodes measures the swing of the oscillator and produces a DC feedback signal that controls a series voltage regulator that supplies power to the oscillator. The calibration procedure in the manual makes use of a 661 to accurately view the output waveform.
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Front view
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Top internal view
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Bottom internal view
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Left internal view
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Right internal view
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Rear view
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Schematic
