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{{Oscilloscope Sidebar|
{{Oscilloscope Sidebar  
title=Tektronix 7844|
|manufacturer=Tektronix
image=Tek7844-front.jpg|
|series=7000-series scopes
caption= |
|model=7844
introduced=1975 |
|summary=400 MHz dual-beam non-storage mainframe
discontinued=1988 |
|image=Tek7844-front.jpg
summary=
|caption=Tektronix 7844 Opt.78 (P11 phosphor)
400 MHz dual-beam non-storage mainframe|
|introduced=1974
manuals=
|discontinued=1988  
* [http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%207844%20R7844%20Instruction.pdf 7844/R7844 Operator's Manual] (Rev. 11/1981, PDF, 3 MB)
|designers=Murlan Kaufman;Chuck Scott;Dick Anderson;Keith Taylor;Bob White
* [http://bama.edebris.com/manuals/tek/7844/ Tek 7844 Service Manual] at BAMA (Rev. 02/1982, PDF, 109 MB)
|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.
Line 20: Line 24:
{{BeginSpecs}}
{{BeginSpecs}}
{{Spec | Bandwidth | 400 MHz with [[7A19]], [[7A29]] (eq. 0.9 ns rise time), 300 MHz with [[7A24]] }}
{{Spec | Bandwidth | 400 MHz with [[7A19]], [[7A29]] (eq. 0.9 ns rise time), 300 MHz with [[7A24]] }}
{{Spec | Fastest calibrated sweep | 1 ns (with [[7B80]], [[7B85]], [[7B92A]]) }}
{{Spec | Fastest calibrated sweep | 1 ns/Div (with [[7B80]], [[7B85]], [[7B92A]]) }}
{{Spec | Beam isolation | > 100:1 from DC to 150 MHz, > 30:1 from 150 MHz to 400 MHz }}
{{Spec | Beam isolation | > 100:1 from DC to 150 MHz, > 30:1 from 150 MHz to 400 MHz }}
{{Spec | X-Y Phase Shift | < 2° from DC to min. 50 kHz }}
{{Spec | X-Y Phase Shift | < 2° from DC to min. 50 kHz }}
{{Spec | Horizontal bandwidth | DC to at least 1 MHz }}
{{Spec | Horizontal bandwidth | DC to at least 1 MHz }}
{{Spec | Z axis input | 2 V<sub>p-p</sub> for full intensity range (positive decreases), input impedance 500 Ω, rise time 15  ns, max. 1 MHz }}
{{Spec | Z axis input | 2 V<sub>p-p</sub> for full intensity range (positive decreases), input impedance 500 Ω, rise time 15  ns, max. 1 MHz }}
{{Spec | CRT | [[154-0713-00]] with P-31 phosphor, or [[154-0713-04]] with P-11 phosphor (Opt. 78), acceleration 24 kV (-3/+21) }}
{{Spec | CRT | [[T7840]], p/n [[154-0713-00]] with P31 phosphor, or [[154-0713-04]] with P11 phosphor (Opt. 78), acceleration 24 kV (−3/+21) }}
{{Spec | Calibrator | 4 mV, 40 mV, 400 mV or 4 V into >100 kΩ, 0.4 mV, 4 mV, 40 mV or 400 mV into 50 Ω; 1 kHz }}
{{Spec | Calibrator | 4 mV, 40 mV, 400 mV or 4 V into >100 kΩ, 0.4 mV, 4 mV, 40 mV or 400 mV into 50 Ω; 1 kHz }}
{{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 7844's CRT has [[distributed vertical deflection plates]].  It uses a number of custom ICs, such as [[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.  
Line 39: Line 56:
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 switch mode PSUs, the 7844 does have a fan.
Unlike some other 7000 series mainframes with switchmode PSUs, the 7844 does have a fan.
 
==Links==


* [http://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)]
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.
* [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


==Prices==
==Prices==
Line 56: Line 68:
! 1980
! 1980
! 1984
! 1984
! 1990<br />(7844R)
! 1990<br />(R7844)
|-
|-
!rowspan=2| Mainframe only
!rowspan=2| Mainframe only
Line 65: Line 77:
|align=right| $19,500
|align=right| $19,500
|-
|-
! 2014 value
! In 2023 dollars
|align=right| $25,320
|align=right| $32,600
|align=right| $26,150
|align=right| $33,700
|align=right| $30,540
|align=right| $39,300
|align=right| $35,230
|align=right| $45,400
|-
|-
!rowspan=2| Mainframe with 2 × [[7A19]],<br />[[7B85]], [[7B80]]
!rowspan=2| Mainframe with 2 × [[7A19]],<br />[[7B85]], [[7B80]]
Line 78: Line 90:
|align=right| $30,660
|align=right| $30,660
|-
|-
! 2014 value
! In 2023 dollars
|align=right| $39,430
|align=right| $50,800
|align=right| $40,910
|align=right| $52,700
|align=right| $48,910
|align=right| $63,000
|align=right| $55,400
|align=right| $71,300
|}
|}
==Pictures==
==Pictures==


Line 89: Line 102:
Tek7844-front.jpg              | Tektronix 7844 front view
Tek7844-front.jpg              | Tektronix 7844 front view
Tek7844-rear.jpg              | Tektronix 7844 rear view
Tek7844-rear.jpg              | Tektronix 7844 rear view
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]](?), [[7B80]] and [[7B85]])
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
Tektronix r7844.jpg           | Tektronix R7844
R7844-rear.jpg                 | Tektronix R7844, rear view
Wellenkino 7844.jpg            | 7844 with options 78 (blue P11 phosphor) and 21 (dedicated vertical slots, i.e. no vertical mode switch)
Wellenkino 7844.jpg            | 7844 with options 78 (blue P11 phosphor) and 21 (dedicated vertical slots, i.e. no vertical mode switch)
Tek 7844 top.jpg              |
Tek 7844 top.jpg              |
Line 102: Line 116:
==Interior==
==Interior==
<gallery>
<gallery>
Tek7844-right.jpg              | Right interior.  Top row: Calibrator board (l), [[7000 series readout system|readout board]] (c), beam 2 horizontal amplifier (r), fan.  
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)
Line 110: Line 124:
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>
{{CRTs|7844}}
{{Custom ICs|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]]

Latest revision as of 11:05, 7 December 2023

Tektronix 7844
400 MHz dual-beam non-storage mainframe
Tektronix 7844 Opt.78 (P11 phosphor)

Produced from 1974 to 1988

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

The Tektronix 7844 is a 400 MHz dual-beam CRT oscilloscope 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.

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 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.

Key Specifications

Bandwidth 400 MHz with 7A19, 7A29 (eq. 0.9 ns rise time), 300 MHz with 7A24
Fastest calibrated sweep 1 ns/Div (with 7B80, 7B85, 7B92A)
Beam isolation > 100:1 from DC to 150 MHz, > 30:1 from 150 MHz to 400 MHz
X-Y Phase Shift < 2° from DC to min. 50 kHz
Horizontal bandwidth DC to at least 1 MHz
Z axis input 2 Vp-p for full intensity range (positive decreases), input impedance 500 Ω, rise time 15  ns, max. 1 MHz
CRT T7840, p/n 154-0713-00 with P31 phosphor, or 154-0713-04 with P11 phosphor (Opt. 78), acceleration 24 kV (−3/+21)
Calibrator 4 mV, 40 mV, 400 mV or 4 V into >100 kΩ, 0.4 mV, 4 mV, 40 mV or 400 mV into 50 Ω; 1 kHz
Power 90-132 V or 180-264 V, 48 to 440 Hz, max. 235 W
Weight 16.3 kg (36 lbs) / R7844: 15 kg (33 lbs)
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

Links

Documents Referencing 7844

Document Class Title Authors Year Links
Tekscope 1974 V6 N4.pdf Article A 400-MHz Dual-Beam Oscilloscope Murlan Kaufman 1974

Internals

The 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. Moreover, calibration and adjustment is significantly more work than in a single-beam scope, e.g. CRT geometry trimpots need to be adjusted for matching both beams, not only for best geometry, and these adjustments even interact slightly.

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 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 manual of the 067-0657-00 Normalized Ramp Generator that was use to investigate this issue.

Prices

  Year 1976 1980 1984 1990
(R7844)
Mainframe only Catalog price $6,100 $9,125 $13,435 $19,500
In 2023 dollars $32,600 $33,700 $39,300 $45,400
Mainframe with 2 × 7A19,
7B85, 7B80
Catalog price $9,500 $14,275 $21,520 $30,660
In 2023 dollars $50,800 $52,700 $63,000 $71,300

Pictures

Interior

Option 22


CRTs used in the 7844

Page Part nos Description Designers Used in
T7840 154-0713-00 154-0713-04 dual-beam CRT Conrad Odenthal Ken Hawken 7844

Custom ICs used in the 7844

Page Model Part nos Description Designers Used in
155-0009-00 M001 155-0009-00 horizontal lockout logic Les Larson 7504 7514 7704 7704A R7704 7834 7844 7854 7904 R7903 7904A 7934 7104
155-0011-00 M012 155-0011-00 clock and chop blanking Les Larson 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 M015 155-0012-00 Z Axis Logic Les Larson 485 7504 7514 7704 R7704 7704A 7834 7844 7854 7904 R7903 7904A R7912 7934 7912AD 7912HB 7104 R7103
155-0022-00 M036 155-0022-00 155-0022-01 analog multiplexer Gene Andrews 147 148 149 335 468 1430 1441 1461 1900 1910 2220 2221 2230 5223 5403 5440 5441 5443 5444 5A38 7313 7403N 7503 7504 7514 7603 AN/USM-281C 7613 7623 7623A 7633 7704 R7704 7704A 7834 7844 7854 R7912 7912AD 7912HB 7904 R7903 7904A 7934 7A12 7A18 7A18A 7A18N 7B52 7B53N 7D10 7D11 7D12 NT-7000 P7001
155-0059-00 M077A 155-0059-00 HF amplifier Thor Hallen 7834 7844 7854 7904 R7903 R7912 7912AD
155-0065-00 H074 155-0065-00 155-0064-01 155-0125-00 deflection amplifier 7844 7904 R7912 R7903
155-0067-02 M091B 155-0067-00 155-0067-02 155-0067-03 SMPS controller Joe Burger Gene Andrews 7704A 7834 7844 7854 7904 R7903 7904 7904A 7934 R7912 7912AD 7912HB 7934 7104 R7103 308 434 485 690 P7001
155-0078-00 M084 155-0078-xx 155-0273-00 155-0274-00 broadband amplifier John Addis 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
155-0095-00 155-0095-00 155-0095-00 155-0095-01 155-0095-03 HF differential amplifier 7834 7844 7904 R7903 R7912 7912AD
203-0126-90 M126 203-0126-90 ft doubler amplifier Hans Springer R7903 7904 7844

Custom ICs used in the 7000 series readout system

Page Model Part nos Description Designers Used in
155-0014-01 M019D 155-0014-00 155-0014-01 A/D converter Barrie Gilbert 7000 series readout system 7854 7934 7J20 7L5 P7001
155-0015-01 M020F 155-0015-00 155-0015-01 analog data switch Barrie Gilbert 7000 series readout system 7854 7934
155-0017-00 M025 155-0017-00 5 MHz decade counter Barrie Gilbert 7000 series readout system 7854 7934
155-0018-00 M026 155-0018-00 zeros logic control Les Larson 7000 series readout system 7934
155-0019-00 M027 155-0019-00 decimal point and spacing control Les Larson 7000 series readout system
155-0020-00 M028 155-0020-00 output assembler Les Larson 7000 series readout system
155-0021-00 M029C 155-0021-00 155-0021-01 timing generator Les Larson 7000 series readout system 7854 7934
155-0023-00 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 M161 155-0024-00 character generator (↓ < I / + - + C Δ >) Barrie Gilbert 7000 series readout system
155-0025-00 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 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 M164 155-0027-00 character generator (U N L Z Y P F J Q D) Barrie Gilbert 7000 series readout system