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Tektronix 5T3
Timing plugin
Tek 5T3

Compatible with 661

Produced from 1965 to (?)

(All manuals in PDF format unless noted otherwise)
Manuals – Specifications – Links – Pictures

The Tektronix Type 5T3 is a timing plug-in for the Type 661 sampling oscilloscope. It uses TD253B tunnel diodes for triggering.

The 5T3 can be triggered from any of four different sources:

  1. Internal trigger from the sampling plug-in, via interconnect J9.
  2. Internal trigger from the calibrator module in the 661 mainframe. This works up to 1 GHz.
  3. External trigger to the high-impedance BNC trigger input. This input is buffered by an 8056 Nuvistor cathode follower. This can be used for triggering on signals up to 20 MHz.
  4. External trigger to the 50 Ω GR-874 trigger input. This input can drive either of two selectable signal paths:
    • A path where the trigger signal skips the high-impedance Nuvistor input buffer but is still buffered by Q64 and Q124 (1 GHz NPN transistors, part number 151-0138-00) before the tunnel diode trigger event recognizer circuit. This path provides triggering up to 500 MHz.
    • A passive low-impedance path, capacitively coupled to a tunnel diode for "UHF SYNC" mode. This works up to 5 GHz.

The 5T3 can also be set to free-run mode.

Key Specifications

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Some Parts Used in the 5T3

Page Class Description Used in
8056 Vacuum Tube (Triode) low-voltage Nuvistor triode 422 502 W 1S1 3A7 3S3 3T4 5T3 10A1