The Tektronix 4S2 is a two-channel sampling vertical plug-in for the 661. Signals enter the 4S2 through GR-874 connectors on the front panel.

Tektronix 4S2
Dual channel sampling plugin

Compatible with 661

Produced from 1962 to (?)


Unlike the 4S1, the 4S2's signal path does not contain a delay line between the input connector and the sampler. This has the advantage of maintaining higher pulse fidelity and thus higher bandwidth, but the disadvantage of making it impossible to see the leading edge of the triggering event unless a pre-trigger is used.

The 4S2, which was designed in 1962, uses a four-diode sampling bridge. The 4S2A, designed in 1965, uses a two-diode sampling bridge. This design change is discussed in the 4S2A Engineering Spec document linked below. The 4S2 does not provide trigger pick-off. The 4S2A provides trigger pick-off for channel A.

The 4S2 and 4S2A front panels look the same, but they use different GR-874 input connectors. The 4S2 uses a short airline unique to the 4S2. The 4S2A uses the connector-to-board system described in US Patent 3,426,311 and has some parts in common with the 3T7.

Key Specifications

Bandwidth DC to 3.9 GHz
Rise time 90 ps
Deflection 2 mV/Div to 200 mV/Div, 1−2−5

See Also





Some Parts Used in the 4S2

Part Part Number(s) Class Description Used in
120-0304-00 120-0304-00 Discrete component inductor 4S1 4S2
152-112 152-112 152-0112-00 Discrete component step recovery diode 4S2
6922 154-0195-00 Vacuum Tube (Dual Triode) dual triode 3S76 4S2
6DJ8 154-0187-00 154-0305-00 Vacuum Tube (Dual Triode) dual triode 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
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

Some Parts Used in the 4S2A

Part Part Number(s) Class Description Used in
152-0252-00 152-0252-00 Discrete component Tek-made step recovery diode 4S2A
6688 154-0215-00 Vacuum Tube (Pentode) miniature high-slope VHF/UHF pentode P80 3T77 3T77A 4S2A 526 TR-4602
7308 154-0371-00 Vacuum Tube (Dual Triode) dual triode 3S76 3S3 4S1 4S2A 4S3 S-311