7904

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The Tektronix 7904 is a 500 MHz, non-storage 7000-series oscilloscope mainframe with four bays. It accepts two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins. It was introduced in late 1971/early 1972 (Note 1). The successor model 7904A was introduced in 1984. There is also a rack-mount version, the R7903, albeit with only one horizontal bay.

Performance is largely determined by the plug-ins. The 7A19 vertical amplifier and 7B92 time base were introduced along with the 7904 to match the 500 MHz system bandwidth.

Design Staff of 7904 Project (from July 1971 Tekscope):

Val Garuts was project manager and developed the large signal amplifier circuit used in the horizontal and Z-axis amplifiers. Thor Hallen did the 7A19 plug-in and the vertical amplifier, and John McCormick the horizontal. The trigger and time base (7B92 plug-in) were done by Les Larson and Bill DeVey. Bill Peek worked on the Z-axis amplifier and auto-focus, with Hans Springer doing the mainframe interface and channel switching. Joe Burger's work on the power supply, coupled with Joel Swanno’s efforts in mechanical design, reduced the weight to only 30 pounds. Ken Hawken did the fine job on the CRT.

Specifications

Bandwidth 500 MHz
Fastest calibrated sweep 500 ps/Div (with 7B92A, other time bases "uncalibrated for first 60 ns")
Acceleration voltage 24 kV (+21 / -3 kV)
Calibrator (7904) 4 mV, 40 mV, 400 mV, 4 V or 40 V (p-p) into 1 MΩ; 2 mV, 20 mV, 200 mV or 400 mV into 50 Ω; or 40 mA; selectable 1 kHz, ½ rep. rate of B Sweep Gate, or DC
Calibrator (7904A) 4 mV to 4 V (p-p) in decade steps, 1 kHz; 40 mV to 400 mV into 50 Ω
Power consumption 190 W
Weight 13.5 kg (30 lbs)
CRT Options

7904A differences

The 7904A re-implements the vertical amplifier using Hypcon-packaged amplifier chips designed for the 7104, such as the 155-0178-00.

The 7904 had an elaborate 5-decade built-in calibrator with variable rate that was dropped from the 7904A. The rear remote control connector unique to the 7904 was dropped as well. In the 7904A, The Control Illumination switch moved to the rear panel, and the readout system gained a pulsed mode in which it is synchronized with the sweep instead of interrupting the display at random times. This pulsed mode is not compatible with all time base plug-ins (see manual p. 1-12).

Options

  • Opt.2: X-Y delay compensation network
  • Opt.3: Extra EMI shielding
  • Opt.4: Maximum-brightness CRT with reduced area
  • Opt.78: P11 phosphor

Operation

The 7904 has many modes of operation. One mode is called "Independent-Pairs Display" in the manual, where the input to the left vertical plug-in is displayed using the B horizontal time-base plug-in, and the input to the right vertical plug-in is displayed using the A horizontal time-base plug-in. This resembles the trace-slaving "ALT" mode that is produced by an 1A4 in a 547. Many other modes are available. It is possible to put vertical plug-ins in the horizontal slots for X-Y operation. It is even possible to put a horizontal plug-in in one of the vertical slots to produce a raster scan.

A special plug-in, the 7A21N, provides direct access to the deflection plates up to 1 GHz at an uncalibrated sensitivity of 4 V/Div. This plugin requires modifications to the mainframe to bypass the Y output amplifier (thus disabling readout and the other vertical plugin bay).

A rear-panel remote control connector has connections for single-sweep ready lamps, a reset button, and readout control.

Internals

The 7904 uses a switch-mode power supply and has no fan. It incorporates a 65 ns Y delay line. This delay is too short for some older time bases such as 7B53 to display the trigger event.

Thor Hallen designed the main vertical amplifier and the 7A19 plugin (Note 1). It used bridged T coils and the "ft doubler" circuit patented by Carl Battjes to achieve its bandwidth.

The 7904 makes extensive use of custom integrated circuits and hybrid circuits, inter alia, the 155-0064-00 470-ps output amplifier, 155-0022-00 analog multiplexer for channel switching, 155-0059-00 HF amplifier, 155-0095-01 and 155-0095-03 differential HF amplifiers, and 155-0067-02 SMPS controller.

The 7904A includes 155-0173-05, 155-0175-05 and 155-0178-05 amplifiers.

The signal path is completely differential and the internal signal wiring is 50 Ω coax. The CRT (154-0644-05) has distributed vertical deflection plates.

Prices

  Year 1972 1976 1980 1984 1990
Model 7904 7904 7904 7904A 7904A
Mainframe only Catalog price $2,900 $4,100 $6,265 $8,810 $12,750
2019 value $17,640 $18,320 $19,330 $21,550 $24,800
Mainframe with 7A19,
7A19 Opt. 04, 7B92
Catalog price $5,500 $7,765 $12,015 $17,425 $24,190
2019 value $33,450 $34,690 $37,070 $42,630 $47,050

Links

Notes

  1. See 7A11 and John Addis, Good Engineering and Fast Vertical Amplifiers, in Jim Williams (Ed.), Analog Circuit Design: Art, Science and Personalities (1991), p.114, and Tektronix New Products 1972 brochure.

Pictures

7904 non-A

Power Supply

7904A

Custom ICs used in the 7904

Page Class Manufacturer Model Part nos Description Designers Used in
155-0009-00 Monolithic integrated circuit Tektronix M001 155-0009-00 horizontal lockout logic Les Larson 7504 7514 7704 7704A 7844 7834 7854 7904 R7903 7904A 7934 7104
155-0010-00 Monolithic integrated circuit Tektronix M004 155-0010-00 chop divider and blanking Les Larson 7504 7514 7704 7704A 7834 7854 7904 R7903 7904A 7934
155-0011-00 Monolithic integrated circuit Tektronix M012 155-0011-00 clock and chop blanking Les Larson 485 4851 4852 7313 7403N 7504 7514 7603 7613 7623 7633 7704 7704A 7834 7844 7854 7904 7904A R7903 7912AD 7912HB 7934 7104
155-0012-00 Monolithic integrated circuit Tektronix M015 155-0012-00 Z Axis Logic Les Larson 485 4851 4852 7504 7514 7704 7704A 7834 7844 7854 7904 R7903 7904A 7934 7912AD 7912HB 7104
155-0013-00 Monolithic integrated circuit Tektronix M022 155-0013-00 horizontal chop and alt. binary Les Larson 7504 7514 7704 7704A 7834 7854 7904 7904A R7903 7934 7104
155-0014-01 Monolithic integrated circuit Tektronix M019D 155-0014-01 A/D converter Barrie Gilbert 7000 series readout system 5403 5440 5441 5443 5444 7313 7504 7514 7603 7613 7623 7633 7704 7704A 7844 7904 R7903 7904A 7912 7J20 P7001
155-0015-01 Monolithic integrated circuit Tektronix M020F 155-0015-01 analog data switch Barrie Gilbert 7000 series readout system 7504 7313 7704 7503 7504 7514 7834 7844 R7903 7904 7912 R7103 7104 5403 5440 5443 5444 7603 7613 7623 7633 7854
155-0022-00 Monolithic integrated circuit Tektronix M036 155-0022-00 155-0022-01 analog multiplexer Gene Andrews 335 468 2220 2221 2230 7403 7503 7603 7613 7623 7623A 7633 7704 7704A 7834 7844 7854 7912AD 7912HB 7904 R7903 7904A 7934 7A12 7A18 7D12 NT-7000 P7001
155-0059-00 Monolithic integrated circuit Tektronix M077A 155-0059-00 HF amplifier Thor Hallen 7834 7844 7854 7904 R7903 R7912 7912AD
155-0060-00 Monolithic integrated circuit Tektronix M071E 155-0060-00 channel selector amplifier Hans Springer R7903 7904 7912
155-0064-00 Hybrid integrated circuit Tektronix H074A 155-0064-00 vertical output amplifier 7834 7854 7904 7903 7912AD 485 PG502
155-0065-00 Hybrid integrated circuit Tektronix H074 155-0065-00 155-0064-01 155-0125-00 deflection amplifier 7844 7904 R7903
155-0067-02 Monolithic integrated circuit Tektronix M091B 155-0067-02 SMPS controller Joe Burger Gene Andrews 7704A 7834 7844 7854 7904 R7903 7904A 7912 7934 7104 308 485 P7001
155-0078-00 Monolithic integrated circuit Tektronix M084 155-0078-xx 155-0273-00 155-0274-00 broadband vertical amplifier John Addis 475 485 7834 7844 7854 7904 R7903 7912AD 7912HB 7A16A 7A16P 7A24 7A26 7A42 067-0587-01 AM503 PG502 PG508 DC510
155-0095-00 Hybrid integrated circuit Tektronix 155-0095-00 155-0095-00 155-0095-01 155-0095-03 HF differential amplifier 7834 7844 7904 R7903 7912AD
155-0178-00 Hybrid integrated circuit Tektronix H488 155-0178-00 horizontal output amplifier Dave Morgan 7904 7912HB 7934 7104
203-0126-90 Monolithic integrated circuit Tektronix M126 203-0126-90 ft doubler amplifier Hans Springer 7903 7904 7844

Custom ICs used in the 7904A

Page Class Manufacturer Model Part nos Description Designers Used in
155-0009-00 Monolithic integrated circuit Tektronix M001 155-0009-00 horizontal lockout logic Les Larson 7504 7514 7704 7704A 7844 7834 7854 7904 R7903 7904A 7934 7104
155-0010-00 Monolithic integrated circuit Tektronix M004 155-0010-00 chop divider and blanking Les Larson 7504 7514 7704 7704A 7834 7854 7904 R7903 7904A 7934
155-0011-00 Monolithic integrated circuit Tektronix M012 155-0011-00 clock and chop blanking Les Larson 485 4851 4852 7313 7403N 7504 7514 7603 7613 7623 7633 7704 7704A 7834 7844 7854 7904 7904A R7903 7912AD 7912HB 7934 7104
155-0012-00 Monolithic integrated circuit Tektronix M015 155-0012-00 Z Axis Logic Les Larson 485 4851 4852 7504 7514 7704 7704A 7834 7844 7854 7904 R7903 7904A 7934 7912AD 7912HB 7104
155-0013-00 Monolithic integrated circuit Tektronix M022 155-0013-00 horizontal chop and alt. binary Les Larson 7504 7514 7704 7704A 7834 7854 7904 7904A R7903 7934 7104
155-0014-01 Monolithic integrated circuit Tektronix M019D 155-0014-01 A/D converter Barrie Gilbert 7000 series readout system 5403 5440 5441 5443 5444 7313 7504 7514 7603 7613 7623 7633 7704 7704A 7844 7904 R7903 7904A 7912 7J20 P7001
155-0022-00 Monolithic integrated circuit Tektronix M036 155-0022-00 155-0022-01 analog multiplexer Gene Andrews 335 468 2220 2221 2230 7403 7503 7603 7613 7623 7623A 7633 7704 7704A 7834 7844 7854 7912AD 7912HB 7904 R7903 7904A 7934 7A12 7A18 7D12 NT-7000 P7001
155-0067-02 Monolithic integrated circuit Tektronix M091B 155-0067-02 SMPS controller Joe Burger Gene Andrews 7704A 7834 7844 7854 7904 R7903 7904A 7912 7934 7104 308 485 P7001
155-0150-00 Hybrid integrated circuit Tektronix H473 155-0150-00 trigger detector circuit Art Metz 7B92A 7B10 7B15 7904A 7104 SCD1000
155-0173-00 Hybrid integrated circuit Tektronix 155-0173-00 155-0173-00 vertical channel switch John Addis Wink Gross 7104 R7103 7904A EG&G N-AM-173A
155-0175-00 Monolithic integrated circuit Tektronix H476 155-0175-00 broadband amplifier John Addis Wink Gross Carl Battjes 7904A 7912HB 7934 7104 R7103 7A29 7A29P 7F10 067-0587-02 067-0587-10 11A71 SCD1000 EG&G N-AM-173A

Custom ICs used in the 7000 series readout system

Page Class Manufacturer Model Part nos Description Designers Used in
155-0014-01 Monolithic integrated circuit Tektronix M019D 155-0014-01 A/D converter Barrie Gilbert 7000 series readout system 5403 5440 5441 5443 5444 7313 7504 7514 7603 7613 7623 7633 7704 7704A 7844 7904 R7903 7904A 7912 7J20 P7001
155-0015-01 Monolithic integrated circuit Tektronix M020F 155-0015-01 analog data switch Barrie Gilbert 7000 series readout system 7504 7313 7704 7503 7504 7514 7834 7844 R7903 7904 7912 R7103 7104 5403 5440 5443 5444 7603 7613 7623 7633 7854
155-0017-00 Monolithic integrated circuit Tektronix M025 155-0017-00 5 MHz decade counter Barrie Gilbert 7000 series readout system
155-0018-00 Monolithic integrated circuit Tektronix M026 155-0018-00 zeros logic control Les Larson 7000 series readout system
155-0019-00 Monolithic integrated circuit Tektronix M027 155-0019-00 decimal point and spacing control Les Larson 7000 series readout system
155-0020-00 Monolithic integrated circuit Tektronix M028 155-0020-00 output assembler Les Larson 7000 series readout system
155-0021-00 Monolithic integrated circuit Tektronix M029C 155-0021-00 timing generator Les Larson 7000 series readout system
155-0023-00 Monolithic integrated circuit Tektronix M160 155-0023-00 character generator (0 1 2 3 4 5 6 7 8 9) Barrie Gilbert 7000 series readout system
155-0024-00 Monolithic integrated circuit Tektronix M161 155-0024-00 character generator (↓ < I / + - + C Δ >) Barrie Gilbert 7000 series readout system
155-0025-00 Monolithic integrated circuit Tektronix M162 155-0025-00 character generator (m μ n p X K M G T R) Barrie Gilbert 7000 series readout system
155-0026-00 Monolithic integrated circuit Tektronix M163 155-0026-00 character generator (S V A W H d B c Ω E) Barrie Gilbert 7000 series readout system
155-0027-00 Monolithic integrated circuit Tektronix M164 155-0027-00 character generator (U N L Z Y P F J Q D) Barrie Gilbert 7000 series readout system