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{{Oscilloscope Sidebar|
{{Oscilloscope Sidebar  
title=Tektronix 7844|
|manufacturer=Tektronix
image=Tektronix 7844.JPG|
|series=7000-series scopes
caption=Tektronix 7844, front view<br/>with [[7A26]], [[7A19]](?), [[7B80]] and [[7B85]] |
|model=7844
years=1972 — ?|
|summary=400 MHz dual-beam non-storage mainframe
summary=
|image=Tek7844-front.jpg
400MHz dual-beam non-storage mainframe|
|caption=  
manuals=
|introduced=1974
* [http://bama.edebris.com/manuals/tek/7844/ Tek 7844 Service Manual] at BAMA
|discontinued=1988
|designers=Murlan Kaufman;Chuck Scott;Dick Anderson;Keith Taylor;Bob White
|manuals=
* [http://w140.com/mmm/tek-7844.pdf Tektronix 7844 Service Manual (October 1981 Revision, 070-1676-02 265MB, PDF)]
* [http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%207844%20R7844%20Instruction.pdf 7844/R7844 Operator's Manual] (Rev. 11/1981, PDF, 3 MB)
* [http://bama.edebris.com/manuals/tek/7844/ Tek 7844 Service Manual] at BAMA (Rev. 02/Oct 1981, 070-1676-02 PDF, 109 MB)
}}
}}
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.
The 7844 is a benchtop lab scope.  There is also a rackmount version, the R7844.
Circuit design for the 7844 was done by [[Chuck Scott]], [[Dick Anderson]], [[Keith Taylor]], and [[Bob White]].
The 7844's CRT has distributed vertical deflection plates.
Project manager for the 7844 was [[Murlan Kaufman]].


A typical configuration might have included [[7A24]] or [[7A19]] amplifiers, a [[7B80]] and a [[7B85]] timebase.
Versions include the 7844 bench-top lab scope and R7844 rack-mount model.


==Specifications==
A typical configuration might have included [[7A19]] or [[7A24]] amplifiers, [[7B80]]/[[7B85]] or [[7B92A]] timebases.
 
{{BeginSpecs}}
{{Spec | Bandwidth | 400 MHz with [[7A19]], [[7A29]] (eq. 0.9 ns rise time), 300 MHz with [[7A24]] }}
{{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 | X-Y Phase Shift | < 2° from DC to min. 50 kHz }}
{{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 | 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 | 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)}}
{{EndSpecs}}
 
==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 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 switch mode PSUs, the 7844 does have a fan.


==Links==
==Links==


* [http://amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/7844.html Tek 7844 page at amplifier.cd]
* [[Media:Tekscope_1974_V6_N4.pdf | A 400 MHz dual-beam oscilloscope. Tekscope Vol.6 No.4, Sept/Oct 1974]]
* [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)]
* [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==
{| class="wikitable"
|-
! &nbsp;
! Year
! 1976
! 1980
! 1984
! 1990<br />(7844R)
|-
!rowspan=2| Mainframe only
! Catalog price
|align=right|  $6,100
|align=right|  $9,125
|align=right| $13,435
|align=right| $19,500
|-
! 2018 value
|align=right| $26,690
|align=right| $27,570
|align=right| $32,200
|align=right| $37,150
|-
!rowspan=2| Mainframe with 2 × [[7A19]],<br />[[7B85]], [[7B80]]
! Catalog price
|align=right|  $9,500
|align=right| $14,275
|align=right| $21,520
|align=right| $30,660
|-
! 2019 value
|align=right| $41,570
|align=right| $43,140
|align=right| $51,570
|align=right| $58,410
|}


==Pictures==
==Pictures==


<gallery>
<gallery>
File:7844-3.jpg
Tek7844-front.jpg              | Tektronix 7844 front view
Image:Tektronix 7844.JPG|Tektronix 7844
Tek7844-rear.jpg              | Tektronix 7844 rear view
Image:Tektronix r7844.jpg|Tektronix R7844
Tek 7844 with 7d15.JPG
File:Wellenkino 7844.jpg
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]])
R7844-2.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)
Tek 7844 top.jpg              |
Tek 7844 rear connections.jpg  |
Tek 7844 left.jpg              |
Tek 7844 right.jpg            |
</gallery>
</gallery>
==Interior==
<gallery>
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-v-b2.jpg              | Beam 2 vertical amplifier, CRT and termination detail (right side)
Tek7844-left.jpg              | Left interior.  Beam 1 vertical amplifier (l), crossover vertical interface (r).
Tek7844-left-above.jpg        | Left/above interior.  Top row: Beam 1 Z axis (l), Beam 1 / Beam 2 horizontal amplifiers (c/r).
Tek-7844-vmode-back.jpg        | Vertical mode switch board, back side
Tek-7844-vmode-back-detail.jpg | Vertical mode switch board, back side (detail)
</gallery>
{{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]]
[[Category:Specifications needed]]
__NOTOC__

Revision as of 04:55, 16 August 2021

Tektronix 7844
400 MHz dual-beam non-storage mainframe

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. 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.

Versions include the 7844 bench-top lab scope and R7844 rack-mount model.

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)

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 switch mode PSUs, the 7844 does have a fan.

Links

Prices

  Year 1976 1980 1984 1990
(7844R)
Mainframe only Catalog price $6,100 $9,125 $13,435 $19,500
2018 value $26,690 $27,570 $32,200 $37,150
Mainframe with 2 × 7A19,
7B85, 7B80
Catalog price $9,500 $14,275 $21,520 $30,660
2019 value $41,570 $43,140 $51,570 $58,410

Pictures

Interior


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