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The Tektronix 125 is a power supply introduced in 1961 for the Type 122 preamplifier. The 125 runs on wall power (mains) and provides three regulated outputs:

  • +135 VDC at 0-20 mA, 1 mV ripple, tube-based regulation
  • -90 VDC at 0-20 mA, 1 mV ripple, tube-based regulation
  • -6 VDC at 0.7-4 A, 4 mV ripple, transistor-based regulation

The +135 V section contains an OG3 voltage reference tube. The -90 V and -6 V sections use the +135 V supply as their reference. All power rectification is done with semiconductor diodes.

A calibration fixture, the 067-0528-00, exists for testing the 125.

The 125, like the 122, appears in three form factors:

  • 125 (standard, vertical orientation, no mounting ears)
  • RM125 (rack mount, horizontal orientation, with wide front panel for mounting mounting in a standard 19" rack, later called "R125")
  • FM125 (frame mount, vertical orientation, for use in the 014-002 mounting frame, later called "F125")


Tektronix 122 and 125 Manual