485

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Tektronix 485
350 MHz portable scope
Tektronix 485

Produced from 1972 to 1986

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

The Tektronix 485 is a dual-trace, portable analog oscilloscope with a maximum bandwidth of 350 MHz, introduced in March of 1972.

The impedance of the inputs can be set individually to 50 Ω or 1 MΩ. The scope achieves its maximum bandwidth when the inputs are in 50 Ω mode.

A distinguishing feature – at least in a portable oscilloscope of its period – is the Alternate Horizontal Mode. In this mode, the B timebase is shown in a separate full-width scan, as opposed to the more common Mixed Mode, where the B timebase is shown on the same line as the A timebase, after the delay time.

The 465, which was introduced after the 485, only received this feature in its "B" incarnation (465B).

Variant 485-1 omits the "A EXT Trigger display", as does variant 485-2 which additionally only has 50 Ω inputs.

John Addis was project leader for the vertical section, assisted by Wink Gross. Glenn Bateman, Ron Peltola and Bob Firth designed the low- and high-impedance attenuators. Murlan Kaufman was project leader for the horizontal and logic systems and designed the trigger generator. Bob White designed the trigger amplifier and external trigger view circuits. Keith Taylor did the work on the fast sweeps, the horizontal and the Z-axis amplifiers. Dick Troberg designed the high efficiency power supply system.

Key Specifications

Input Impedance 50 Ω / 1 MΩ // 20 pF
Rise time 1 ns (50 Ω) / 1.4 ns (1 MΩ)
Bandwidth 350 MHz (50 Ω) / 250 MHz (1 MΩ)
Deflection 5 mV/div to 5 V/div in 1−2−5 sequence, 2% accuracy
Time Base 1 ns/div to 0.5 s/div in 1−2−5 sequence
CRT P31: 154-0652-00 / 154-0652-05 (B091500+); P11 (Opt.78): 154-0652-04 / 154-0652-09 (B091500+); 21 kV acceleration, 8 × 10 divisions (0.8 cm/div)
Calibrator 5 V into 1 MΩ / 0.5 V into 50 Ω / 50 mA using optional loop adapter, 1 kHz or 1 MHz, rise time less than 1 ns, output resistance 450 Ω
Outputs Positive gates from both time bases (~4 V), positive-going sawtooth from Time Base A (~10 V)
Weight 9.3 kg (21.5 lb)
Power AC 90–136 or 180–272 V, 48–440 Hz, 60 W @ 115V

Links

Documents Referencing 485

Document Class Title Authors Year Links
Tekscope 1972 V4 N2 Mar 1972.pdf Article A Nanosecond Portable Oscilloscope Gene Andrews 1972

Patents that may apply to 485

Page Title Inventors Filing date Grant date Links
Patent US 3906344A Oscilloscope having selectable input impedances John Addis Ron Peltola 1974-04-04 1975-09-16

Prices

Year 1972 1973 1976 1980 1982 1986
Catalog Price $4,200 $4,200 $4,550 $6,035 $6,975 $9,100
In 2023 Dollars $30,900 $29,100 $24,600 $22,500 $22,200 $25,600

Internals

The 485 includes a switching power supply and uses custom integrated circuits for most of the gain blocks. Triggering uses tunnel diodes.

Pictures

External

Internals

Components

Some Parts Used in the 485

Part Part Number(s) Class Description Used in
148-0034-01 148-0034-01 Discrete component miniature DPDT relay 485 7A12
154-0652-00 154-0652-00 154-0652-04 154-0652-05 154-0652-09 CRT CRT 485 485R 485-1 485-2
155-0011-00 155-0011-00 Monolithic integrated circuit clock and chop blanking 485 7313 7403N R7403N 7503 7504 7514 7603 AN/USM-281C 7613 7623 7623A 7633 7704 R7704 7704A 7834 7844 7854 7904 7904A R7903 R7912 7912AD 7912HB 7934 7104 R7103 AN/USM-281C
155-0012-00 155-0012-00 Monolithic integrated circuit Z Axis Logic 485 7504 7514 7704 R7704 7704A 7834 7844 7854 7904 R7903 7904A R7912 7934 7912AD 7912HB 7104 R7103
155-0049-00 155-0049-00 155-0049-01 155-0049-02 Monolithic integrated circuit sweep control with lockout 335 464 465 466 475 475A 475M 485 5B31 5B40 5B52 5B42 5B44 7B53A 7B80 7B85 7B87 7B92A 7B90P 7B10 7B15 SC502 7B42N AN/USM-281C 067-0657-00
155-0064-00 155-0064-00 Hybrid integrated circuit vertical output amplifier 7834 7854 7904 R7903 7912AD 485 PG502
155-0067-02 155-0067-00 155-0067-02 155-0067-03 Monolithic integrated circuit SMPS controller 7704A 7834 7844 7854 7904 R7903 7904 7904A 7934 R7912 7912AD 7912HB 7934 7104 R7103 308 434 485 690 P7001
155-0076-00 155-0076-00 Monolithic integrated circuit input protection and probe logic 465 485 7A29 7A29P 11A52 11A71 11A72 SCD1000
155-0078-00 155-0078-xx 155-0273-00 155-0274-00 Monolithic integrated circuit broadband amplifier 464 465 466 468 475 475A 475M 485 7834 7844 7854 7904 R7903 R7912 7912AD 7912HB 7104 7A16A 7A16P 7A24 7A26 7A42 067-0587-01 067-0680-00 AM503 PG502 PG508 DC510 DC5010 FG5010
SMTD994 152-0177-01 Discrete component 10 mA, 2 pF tunnel diode 067-0587-01 067-0580-00 3T5 3T6 485 5S14N 7D14 7T11 7T11A S-53
SMTD998 152-0177-02 Discrete component 10 mA, 2 pF tunnel diode 067-0681-01 485 7B92 7B92A