551

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Tektronix 551
27 MHz scope
Tektronix 551

Produced from 1958 to 1973

Manuals
Manuals – Specifications – Links – Pictures

The Tektronix Type 551, introduced in 1958, is a 27 MHz dual-beam scope that takes two letter-series and 1-series plug-ins.

Unlike the 555, it has only one set of horizontal deflection plates and the trigger and sweep circuitry are built in to the mainframe. The vertical amplifiers of the 545A, 551, and 555 are identical. The 551 uses an L-C delay line for each vertical channel.

Like the 555, the 551 has two parts, the "indicator unit" containing the signal path electronics and CRT, and an external power supply unit. The external power supplies of the 555 and 551 are not interchangeable, however, the cable that connects the power supply to the indicator unit (part number 012-032) is the same for the 551 and the 555.

The filament current for the tubes in the indicator unit is produced by a transformer in the indicator unit, T750 (part number 120-235), that has seven isolated secondaries, each supplying 6.3 VAC. The indicator unit also contains the CRT circuit, which uses 5642 tubes and produces the +8650 V CRT anode voltage and the −1350 V voltage for the CRT cathode. The external power supply unit produces regulated DC voltages of −150 V, +100 V, +225 V, +350 V, and +500 V.

A factory modification, MOD 108A, was available for increasing the CRT acceleration voltage from 10 kV to 12 kV to improve trace visibility at high sweep rates, at the cost of reducing deflection sensitivity to 0.85 cm/Div. A graticule with 0.85 cm units was supplied.

Early 551 units used UHF connectors. Many were converted in the field to use BNC connectors.

Key Specifications

CRT T57 (T551) in early, T5511 in later (SN 2032+) models
Comparison of 551 with 555
551 555
Rise time with Type K 14 ns 12 ns
Acceleration Voltage 10 kV 10 kV
Filament Regulation none saturable core reactor
Price in 1965
(2015 equiv.)
$1,850
($14,000)
$2,650
($20,100)
Indicator Weight 52 lb (23.6 kg) 68 lb (30.8 kg)
Power Supply Weight 42 lb (19 kg) 45 lb (20.4 kg)
Power Consumption 850 W 1050 W

Links

Pictures


Some Parts Used in the 551

Part Part Number(s) Class Description Used in
120-235 120-235 120-0235-01 Discrete component filament power transformer 551
12B4 154-044 154-0044-00 Vacuum Tube (Triode) power triode 126 310 310A 316 317 502 502A 524 526 541 541A 535 535A 545 545A 546 547 570 549 551 555 513 581 581A 585 585A
5642 154-0051-00 154-0079-00 Vacuum Tube (Diode) directly-heated high-voltage rectifier 310 310A 316 317 360 453 502 502A 503 504 506 513 515 516 524 529 RM529 533 533A 535 536 543 543A 543B 545 545A 545B 547 551 555 556 560 561 561A 561S 564 567 570 575 581 581A 585 585A 647 647A
6AL5 154-016 154-0016-00 154-0038-00 Vacuum Tube (Dual Diode) high-perveance dual diode 163 181 190 1M1 310 310A 315 316 317 3B1 3B1S 3B2 3B3 3B5 502 502A 503 511 511A 512 516 517 517A 524 526 535 535A 545 545A 549 551 565 570 581 581A 585 585A C T Telequipment D56 Telequipment S52
6DK6 154-0149-00 154-0367-00 Vacuum Tube (Pentode) high-frequency miniature pentode 180 503 513 514 541 543 535 545 545A 551 555
T5511 154-0186-00 154-0160-00 154-0210-00 154-0189-00 154-0143-00 CRT dual-beam CRT 551
T57 154-0186-00 154-0160-00 154-0210-00 154-0189-00 154-0143-00 CRT dual-beam CRT 551