7844

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Tektronix 7844
400 MHz dual-beam non-storage mainframe
Tek7844-front.jpg

Produced from 1974 to 1988

Manuals
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.

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 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
155-0011-00 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
155-0014-01 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
155-0065-00 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
203-0126-90 Monolithic integrated circuit Tektronix M126 203-0126-90 ft doubler amplifier Hans Springer 7903 7904 7844

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