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{{Oscilloscope Sidebar | |||
|manufacturer=Tektronix | |||
|series=7000-series scopes | |||
|model=7904A | |||
|designers= | |||
|image=7904a-front.jpg | |||
|caption=Tektronix 7904A | |||
|introduced=1984 | |||
|discontinued=1990 | |||
|summary=500 MHz non-storage mainframe | |||
|manuals= | |||
* [[Media:070-4593-00.pdf|Tektronix 7904A Manual, May 1989 Revision]] (OCR, low quality scan, whole schematics) | |||
* [[Media:070-4593-00 hires split schematics.pdf|Tektronix 7904A Manual, May 1989 Revision]] (OCR, good quality scan, split schematics) | |||
}} | |||
The '''Tektronix 7904A''' is a 500 MHz, non-storage 7000-series oscilloscope mainframe with four bays, introduced in 1984. | |||
It is a redesign of the predecessor model [[7904]] from 1971, using integrated circuits developed for the 1 GHz [[7104]]. | |||
{{BeginSpecs}} | |||
{{Spec | Bandwidth | 500 MHz (with [[7A19]] or [[7A29]] amplifier) }} | |||
{{Spec | Fastest calibrated sweep | 500 ps/Div (with [[7B92A]], other time bases "uncalibrated for first 60 ns") }} | |||
{{Spec | Trigger Source | Left / Vert Mode / Right }} | |||
{{Spec | Outputs | Vertical Signal Out (25 mV/Div into 50 Ω, 0.5 V/Div into 1 MΩ); +Sawtooth; +Gate; camera power; probe power }} | |||
{{Spec | Inputs | Z Axis (15 V<sub>p-p</sub>) }} | |||
{{Spec | CRT | | |||
* Standard: (8×10 Div @ 1 cm), P31 (green) [[154-0644-05]] or P11 (blue) [[154-0644-09]], acceleration voltage 24 kV (+21 / –3 kV) | |||
* Option 4, high writing speed: (8×10 Div @ 0.5 cm) , P31 (green) [[154-0661-05]] or P11 (blue) [[154-0661-09]] | |||
}} | |||
{{Spec | Calibrator | DC, square wave (1 kHz or ½ B Sweep gate), 4 mV to 40 V in decade steps (2/20/200/400 mV into 50 Ω); 40 mA current loop }} | |||
{{Spec | Power | 90−132 V or 180−264 V, 48−440 Hz, 190 W max. }} | |||
{{Spec | Weight | 13.5 kg (30 lbs) }} | |||
{{Spec | Dimensions | 34.2 cm × 30.5 cm × 69.5 cm (13.5 in x 12.0 in x 23.8 in) H×W×L }} | |||
{{Spec|Options| | |||
* Opt.1: deletes read out system | |||
* Opt.2: X-Y delay compensation network | |||
* Opt.3: Extra EMI shielding | |||
* Opt.4: Maximum-brightness CRT with reduced area | |||
* Opt.78: P11 phosphor | |||
}} | |||
{{EndSpecs}} | |||
==Links== | |||
* [http://amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/7904A.htm 7904A] @ amplifier.cd | |||
* [https://www.circuitsathome.com/measurements/repairing-front-panel-buttons-of-tektronix-7904-oscilloscope Repairing front panel buttons of Tektronix 7904 oscilloscope] | |||
* [https://www.youtube.com/watch?v=GQn0EqW-u74 Tektronix 7904A lab check in and LED MOD] by Zenwizard Studios @ YouTube | |||
{{Documents|Link=7904A}} | |||
{{PatentLinks|7904A}} | |||
==Internals== | |||
The 7904A 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. | |||
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]]. | |||
===Differences to 7904 === | |||
The 7904A borrows heavily from the 1 GHz [[7104]] introduced in 1978 in terms of front panel layout, mechanical design, and electronics, re-implementing the vertical amplifier using Hypcon-packaged amplifier chips such as the [[155-0173-05]], [[155-0175-05]] and [[155-0178-05]]. | |||
The 7904 had the elaborate 5-decade built-in calibrator with variable rate that was common on all first-generation 4-bay [[7000-series scopes]], it was dropped from the 7904A. | |||
The [[7000-series remote control connector|rear remote control connector]] unique to early 7000-series scopes was dropped as well. | |||
In the 7904A, The Control Illumination switch moved to the rear panel, and the [[7000 series readout system|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). | |||
In addition, the 7904A adds a fan in the SMPS. | |||
==Prices== | |||
{| class="wikitable" | |||
|- | |||
! | |||
! Year | |||
! 1984 | |||
! 1990 | |||
|- | |||
! Model | |||
| | |||
|align=center| 7904A | |||
|align=center| 7904A | |||
|- | |||
!rowspan=2| Mainframe only | |||
! Catalog price | |||
|align=right| $8,810 | |||
|align=right| $12,750 | |||
|- | |||
! In 2024 Dollars | |||
|align=right| $26,600 | |||
|align=right| $30,600 | |||
|- | |||
!rowspan=2| Mainframe with [[7A19]],<br />7A19 Opt. 04, [[7B92]] | |||
! Catalog price | |||
|align=right| $17,425 | |||
|align=right| $24,190 | |||
|- | |||
! In 2024 Dollars | |||
|align=right| $52,700 | |||
|align=right| $58,100 | |||
|} | |||
==Pictures== | |||
<gallery> | |||
7904a-front.jpg |7904A | |||
7904A_rear.jpg |7904A Rear | |||
7904A_top1.jpg |7904A Top with Horizontal Amplifier at top right | |||
7904A_right1.jpg |7904A Right with Z-axis on top right and 2nd Gen. Readout board at bottom right | |||
7904A_left1.jpg |7904A Left with Vertical Amplifier (top) and Vertical switch board (bottom) | |||
7904A_topleft1.jpg |7904A Topleft | |||
7904A_left_closeup.jpg |7904A Closeup of Vertical amplifier | |||
7904a lvps1.png|7904A Low-voltage Power Supply Schematic | |||
7904a-h-v.jpg | 7904A Horizontal and vertical amplifiers | |||
</gallery> | |||
==Parts== | |||
{{Parts|7904A}} | |||
{{Custom ICs|7000 series readout system}} | |||
[[Category:7000 series non-storage mainframes]] | [[Category:7000 series non-storage mainframes]] | ||