3T77

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Tektronix 3T77
Sampling sweep plug-in
Tektronix 3T77 front

Compatible with 560-series scopes

Produced from 1962 to 1973

Manuals
Manuals – Specifications – Links – Pictures

The Tektronix 3T77 is a sampling sweep plug-in for 560-series scopes. It was introduced in 1962, along with the 567 and 3S76.

Bob Webb and maybe Jim Geddes and possibly Cliff Moulton designed the Type 77, which evolved into the 3T77.

It triggers on either the internal trigger pick-off from the vertical plug-in or from an external trigger signal input. Triggering is faster and more sensitive with an external input.

The 3T77 can operate in any of four modes: external sweep, manual sweep, normal, or single sweep. In external sweep mode, an external control voltage is applied to a BNC connector on the front panel of the 3T77. This voltage determines the X-position of the spot on the CRT and, correspondingly, the delay from the trigger event to the sampling point. Manual mode is the same as external sweep mode, but the control voltage is generated internally based on the position of a potentiometer on the front panel of the 3T77. In normal mode, an internal ramp generator produces the control voltage, repeatedly redrawing the trace on the CRT. In single sweep mode, the internal ramp generator is started by a button on the front panel, makes on horizontal trace, and then waits for the button to be pressed again.

Internals

While still tube-based, the 3T77 uses 2N976 transistors and 1N3129 tunnel diodes. It uses a 6688 tube in the staircase generator circuit, and an RCA 7586 nuvistor as a ramp-current generator. The 3T77 mixes "classic" chassis/ceramic strip construction with the trigger circuit built on a PCB.

Difference of 3T77 and 3T77A

TIME POSITION knob instead DELAY knob, with more range of delay by slow sweep rate.

RECOVERY TIME knob can be pulled for HF-sync.

Specifications

please add

Pictures

3T77 Photos

3T77 Schematics

3T77A Photos


Some Parts Used in the 3T77

Part Part Number(s) Class Description Used in
1N3128 152-0074-00 152-074 Discrete component 5 mA, 15 pF germanium tunnel diode 3T77 5T1
1N3129 152-0043-00 Discrete component 20 mA Germanium tunnel diode 3T77 5T1
6688 154-0215-00 Vacuum Tube (Pentode) miniature high-slope VHF/UHF pentode P80 3T77 3T77A 4S2A 526 TR-4602
6DJ8 154-0187-00 154-0305-00 Vacuum Tube (Dual Triode) dual triode 067-506 111 132 161 310A 316 317 502 502A 503 504 506 515 516 519 526 529 RM529 533 535 536 543 544 545 545A 545B 546 547 549 555 556 561A 561S 564 565 567 581 581A 585 585A 661 1A4 1S1 60 2A60 63 2A63 67 2B67 3A1 3A1S 3A2 3A3 3A6 3A7 72 3A72 75 3A75 4S2 51 3B1 3B1S 3B2 3B3 3B4 3M1 3S76 3T77 3T77A 9A1 9A2 1121 80 81 82 86 B O W Z Telequipment D56 Telequipment S32A Telequipment D52 S-311 Telequipment TD51 Telequipment S52 Telequipment S51 Telequipment Type A TU-4
6EW6 154-0212-00 Vacuum Tube (Pentode) pentode 106 132 360 51 527 581 581A 585 585A 3T77 3T77A
7586 154-0306-00 Vacuum Tube (Triode) Nuvistor triode M 1A1 1A2 1A5 10A2 10A2A 11B1 11B2A 321 321A 3A1 3A1S 3A3 3A5 3A6 3A7 3A8 3A74 3S76 3T77 3T77A 3B5 4S1 4S2 6R1 6R1A 9A1 9A2 82 86 S-311
RT5204 151-0058-00 Discrete component Silicon NPN transistor 565 RM565 Z 2A61 3B1 3B3 3S76 3T77