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{{Oscilloscope Sidebar| | {{Oscilloscope Sidebar | ||
|manufacturer=Tektronix | |||
image=Tek7844-front.jpg| | |series=7000-series scopes | ||
caption= | | |model=7844 | ||
introduced=1974 | | |summary=400 MHz dual-beam non-storage mainframe | ||
discontinued=1988 | | |image=Tek7844-front.jpg | ||
|caption=Tektronix 7844 Opt.78 (P11 phosphor) | |||
|introduced=1974 | |||
manuals= | |discontinued=1988 | ||
* [ | |designers=Murlan Kaufman;Chuck Scott;Dick Anderson;Keith Taylor;Bob White | ||
|manuals= | |||
* [ | * [[Media:070-1675-00.pdf|7844 Operator Manual]] (OCR) | ||
* [[Media:070-1676-02.pdf|7844 Service Manual]] (OCR) | |||
}} | }} | ||
The '''Tektronix 7844''' is a 400 MHz [[dual-beam scopes|dual-beam CRT oscilloscope]] | The '''Tektronix 7844''' is a 400 MHz [[dual-beam scopes|dual-beam CRT oscilloscope]] that takes two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins. | ||
that takes two 7000-series vertical plug-ins and two 7000-series horizontal plug-ins | |||
Versions include the 7844 bench-top lab scope and R7844 rack-mount model. | Versions include the 7844 bench-top lab scope and R7844 rack-mount model. | ||
Circuit design for the 7844 was done by [[Chuck Scott]], [[Dick Anderson]], [[Keith Taylor]], and [[Bob White]]. Project manager for the 7844 was [[Murlan Kaufman]]. | |||
The [[T7840|7844's CRT]] was designed by [[Conrad Odenthal]] and [[Ken Hawken]]. | |||
A typical configuration might have included [[7A19]] or [[7A24]] amplifiers, [[7B80]]/[[7B85]] or [[7B92A]] timebases. | A typical configuration might have included [[7A19]] or [[7A24]] amplifiers, [[7B80]]/[[7B85]] or [[7B92A]] timebases. | ||
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{{Spec | Power | 90-132 V or 180-264 V, 48 to 440 Hz, max. 235 W }} | {{Spec | Power | 90-132 V or 180-264 V, 48 to 440 Hz, max. 235 W }} | ||
{{Spec | Weight | 16.3 kg (36 lbs) / R7844: 15 kg (33 lbs)}} | {{Spec | Weight | 16.3 kg (36 lbs) / R7844: 15 kg (33 lbs)}} | ||
{{Spec | Options | | |||
* Opt.03 – EMI shielding | |||
* Opt.21 – Dedicated vertical deflection system (eliminates vertical mode switch and crossover board) | |||
* Opt.22 – Enhancer (generates raster scan to illuminate the entire CRT at the end of beam 2 sweep) | |||
* Opt.78 – P11 phosphor | |||
}} | |||
{{EndSpecs}} | {{EndSpecs}} | ||
==Links== | |||
* [https://amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/7844.html Tek 7844 page at amplifier.cd] and a [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/rep-und-kal/7844_reparatur_engl.html repair report (switch-mode PSU)] | |||
* [http://www.barrytech.com/tektronix/tek7000/tek7844.html Tek 7844 @ barrytech.com] | |||
* [http://www.firstpr.com.au/tequip/R7844/ R7844 page with frequency response measurements] | |||
* [http://www.jvgavila.com/tek7844.htm Tek R7844 page @ EB5AGV], lots of internal photos | |||
{{Documents|Link=7844}} | |||
==Internals== | ==Internals== | ||
The [[T7840 | 7844's CRT]] has [[distributed vertical deflection plates]]. It uses a number of custom ICs, such as [[155-0064-00]], [[155-0065-00]] and [[155-0059-00]] in the vertical amplifiers, [[155-0095-00]] in the vertical interface, [[155-0078-00]] in the trigger selector, and [[155-0022-00]] in the horizontal interface. The horizontal and Z axis amplifiers are discrete. | The [[T7840|7844's CRT]] has [[distributed vertical deflection plates]]. It uses a number of custom ICs, such as [[155-0064-00]], [[155-0065-00]] and [[155-0059-00]] in the vertical amplifiers, [[155-0095-00]] in the vertical interface, [[155-0078-00]] in the trigger selector, and [[155-0022-00]] in the horizontal interface. The horizontal and Z axis amplifiers are discrete. | ||
The 7844 is more complex than all other 7000 mainframes except the [[7854]] because vertical and horizontal amplifiers as well as the Z axis control boards exist twice, and there is an extra switching logic board. As a consequence, verifying correct operation requires testing many possible combinations of settings – for example, a defect on the vertical switching board could cause a problem only in the case of both beam 1 and 2 using horizontal bay B, but not if beam 1 used A and beam 2 used B. | The 7844 is more complex than all other 7000 mainframes except the [[7854]] because vertical and horizontal amplifiers as well as the Z axis control boards exist twice, and there is an extra switching logic board. As a consequence, verifying correct operation requires testing many possible combinations of settings – for example, a defect on the vertical switching board could cause a problem only in the case of both beam 1 and 2 using horizontal bay B, but not if beam 1 used A and beam 2 used B. | ||
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The power supply is a resonant switch-mode inverter with linear post-regulation, similar to the one in the [[7904]]. It uses the [[155-0067-02]] controller. Despite having an SMPS, the 7844 is fairly heavy behause of the duplicate internal components, especially the second vertical delay line. The delay lines need extra space and are located vertically to the right of the CRT instead of below the CRT as in other 7xx4s. | The power supply is a resonant switch-mode inverter with linear post-regulation, similar to the one in the [[7904]]. It uses the [[155-0067-02]] controller. Despite having an SMPS, the 7844 is fairly heavy behause of the duplicate internal components, especially the second vertical delay line. The delay lines need extra space and are located vertically to the right of the CRT instead of below the CRT as in other 7xx4s. | ||
Unlike some other 7000 series mainframes with | Unlike some other 7000 series mainframes with switchmode PSUs, the 7844 does have a fan. | ||
Early 7844 (SN B109999 and earlier) have issues with horizontal aberrations for sweep rates of 1 ns/Div. After discovery of the issue modification kits (040-0804-00) that replace the horizontal amplifier were offered. For more information see the [[Media:Tek 067-0657-00 with schematics.pdf|manual]] of the [[067-0657-00|067-0657-00 Normalized Ramp Generator]] that was use to investigate this issue. | |||
==Prices== | ==Prices== | ||
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! 1980 | ! 1980 | ||
! 1984 | ! 1984 | ||
! 1990<br />( | ! 1990<br />(R7844) | ||
|- | |- | ||
!rowspan=2| Mainframe only | !rowspan=2| Mainframe only | ||
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|align=right| $19,500 | |align=right| $19,500 | ||
|- | |- | ||
! | ! In 2023 dollars | ||
|align=right| $ | |align=right| $32,600 | ||
|align=right| $ | |align=right| $33,700 | ||
|align=right| $ | |align=right| $39,300 | ||
|align=right| $ | |align=right| $45,400 | ||
|- | |- | ||
!rowspan=2| Mainframe with 2 × [[7A19]],<br />[[7B85]], [[7B80]] | !rowspan=2| Mainframe with 2 × [[7A19]],<br />[[7B85]], [[7B80]] | ||
| Line 81: | Line 90: | ||
|align=right| $30,660 | |align=right| $30,660 | ||
|- | |- | ||
! | ! In 2023 dollars | ||
|align=right| $ | |align=right| $50,800 | ||
|align=right| $ | |align=right| $52,700 | ||
|align=right| $ | |align=right| $63,000 | ||
|align=right| $ | |align=right| $71,300 | ||
|} | |} | ||
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Tek 7844 with 7d15.JPG | Tek 7844 with 7d15.JPG | ||
7844-3.jpg | Simultaneous time and frequency domain display using a [[7A26]] amplifier, [[7B92A]] time base, and [[7L5]] Spectrum Analyzer | 7844-3.jpg | Simultaneous time and frequency domain display using a [[7A26]] amplifier, [[7B92A]] time base, and [[7L5]] Spectrum Analyzer | ||
Tektronix 7844.JPG | Tektronix 7844 front view (with [[7A26]], [[7A19]] | Tektronix 7844.JPG | Tektronix 7844 front view (with [[7A26]], [[7A19]], [[7B80]] and [[7B85]], Opt.03 CRT EMI screen) | ||
R7844-2.jpg | Tektronix R7844 | R7844-2.jpg | Tektronix R7844 | ||
R7844-rear.jpg | Tektronix R7844, rear view | R7844-rear.jpg | Tektronix R7844, rear view | ||
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==Interior== | ==Interior== | ||
<gallery> | <gallery> | ||
Tek7844-right.jpg | Right interior. Top row: Calibrator board (l), [[7000 series readout system|readout board]] (c), beam 2 | Tek7844-right.jpg | Right interior. Top row: Calibrator board (l), [[7000 series readout system|readout board]] (c), beam 2 vertical amplifier (r), fan. | ||
Tek7844-right-above.jpg | Right/above interior. The dual delay lines can be seen behind the readout board. Horizontally mounted boards in the center are: Crossover mode switch (l), trigger selector (c), power supply (r). | Tek7844-right-above.jpg | Right/above interior. The dual delay lines can be seen behind the readout board. Horizontally mounted boards in the center are: Crossover mode switch (l), trigger selector (c), power supply (r). | ||
Tek7844-v-b2.jpg | Beam 2 vertical amplifier, CRT and termination detail (right side) | Tek7844-v-b2.jpg | Beam 2 vertical amplifier, CRT and termination detail (right side) | ||
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Tek-7844-vmode-back-detail.jpg | Vertical mode switch board, back side (detail) | Tek-7844-vmode-back-detail.jpg | Vertical mode switch board, back side (detail) | ||
</gallery> | </gallery> | ||
===Option 22=== | |||
<gallery> | |||
Tek 7844 with Opt 22.jpg | An 7844 with option 22 (board right of the readout). | |||
Tek 7844 Opt 22 board 1.jpg | Opt. 22 board | |||
Tek 7844 Opt 22 board 2.jpg | Readout board (l), Opt. 22 board (r) | |||
Tek 7844 Opt 22 board 3.jpg | Opt. 22 board | |||
</gallery> | |||
==Components== | |||
{{Parts|7844}} | |||
{{Custom ICs|7000 series readout system}} | |||
[[Category:7000 series non-storage mainframes]] | [[Category:7000 series non-storage mainframes]] | ||
[[Category:Dual beam scopes]] | [[Category:Dual beam scopes]] | ||