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[[Image:Tek1502-front.JPG|600px|center]]
{{Instrument Sidebar
|manufacturer=Tektronix
|model=1502
|class=Reflectometer
|series=
|summary=Time Domain Reflectometer
|image=Tek1502-front.JPG
|caption=Tektronix 1502 Time Domain Reflectometer (CRT version)
|introduced=1975
|discontinued=(?)
|designers=Hans Geerling
|manuals=
'''1502'''
* [[Media:070-1790-00.pdf|Tektronix 1502 Operators Manual]]
* [[Media:070-1792-01.pdf|Tektronix 1502 Service Manual -01]]
* [[Media:070-1792-02.pdf|Tektronix 1502 Service Manual -02]]
* High-res 1502 schematics:
** [[Media:1502_Vertical_Amp.pdf|Vertical amp board]]
** [[Media:1502_Schematic_Mainborad_Components.pdf|Main board]]
** [[Media:1502_SCHEMATIC-Output_Amp.png|Output amplifier]]
* [[Media:Tek_1502_Wizard_Workshop.pdf|Tektronix 1502 Wizard Workshop Articles]]
* [[Media:Tek_1502_mods.pdf|Tektronix 1502 Modifications]]


The Tektronix 1502 is a series of Time Domain Reflectometers commonly used to test coaxial
'''1502B'''
cables athough they have many other uses. The US military was a major purchaser; most of the
* [[Media:070-6266-01.pdf|Tektronix 1502B Operator Manual]]
first series (the 1502, no letter) will be found surplus with some sort of US military
* [[Media:070-6267-04.pdf|Tektronix 1502B Service Manual]]
property ID tag and an NSN sticker.


The first version used a CRT and is almost completely analog along with some discrete digital
'''1502C'''
logic used to prefire and fire the [[tunnel diodes|tunnel diode]] pulser.  The later models (1502B/C) used an
* [[Media:070-7169-05.pdf|Tektronix 1502C User Manual]]
LCD display and a microprocessor.  The other major difference is the line charging method.
* [[Media:070-7168-04.pdf|Tektronix 1502C Service Manual]]
The 1502 uses a fast (36 ps) tunnel diode pulser, the later models used a half sine wave to
charge the line.  The TD pulser, with it's Dirac delta edge gives much better short range
sensitivity although it is much easier to destroy.


There are four key parts in the 1502 that make repair difficult.  The original sampling gate (CR1732, Tek 152-0631-00) is no longer available, but Avago RF Schottky barrier diodes in the SOT series pair package (Avago HSMS-2822, HSMS-282C) are a close substitute.
'''Other'''
* [[Media:Tektronix_Y-T_chart_recorder.pdf|Tektronix Chart Recorder User/Service Manual]]


There is a [[snap-off diode]] (CR1632, Tek [[152-0335-01]]) in the samping gate pulse shaper that is also no longer available but it usually doesn't fail. 
* [[Media:070-2178-00.pdf|Watertight Sealing Procedures for 1502/1503 TDRs]]
* [[Media:Optimize falltime and aberrations 1502.pdf|Guide to Optimizing Falltime and Aberrations in the 1502]]


The first pulse shaping TD (CR1609, tek [[152-0140-01]], 10 mA, 8 pF) was a fairly common TD and there are Russian substitutes available.  The primary fast pulse TD (CR1703, Tek [[152-0489-00]], 21 mA, 1.5 pF) is simply no longer available.  Good Luck!
:''Note that the manuals for the 1502B and 1503C are still available from Tektronix.''
}}
The '''Tektronix 1502''' is a series of Time Domain Reflectometers which replaced the [[1501]] in 1975.  The 1502 is for high resolution, sister model [[1503]] for long range.


If you want to design a replacement, I suggest looking at Analog Devices ADCMP580, and Starecki and Misiaszek's
They are commonly used to test coaxial cables, although they have many other uses.
paper "Low cost programmable pulse generator with very short rise/fall time".
The US military was a major purchaser, therefore most of the first series (the 1502, no letter) will be found surplus with some sort of US military property ID tag and an NSN sticker.


There appears to have been an optional "static supressor" available, Tek 011-0132-00, in a BNC M-F package used to protect the sampler and TD.  It's pretty obscure.
[[Hans Geerling]] did most of the circuit design on the 1502.


The other common failure is the battery.  The power supply was designed to protect both the instrument
{{MissingSpecs}}
and the battery from abuse, so any failure will cause the power supply to latch up (via Q6547/Q6549)
and the unit will appear dead.  The pack is rebuildable with NiCd battery cells.  To operate without
a battery in place use a 200 to 270 Ω / 10 W power resistor in parallel with a 2200 μF cap (> 25 V); this
will fool the power supply protection circuit into thinking that it's charging a valid battery.


Service Manuals:
==Internals and version differences==
* [http://w140.com/TEK-1502-OM-SM-1.pdf Tektronix 1502 Service Manual (PDF)]
The first version used a CRT and is an almost completely analog design except for some discrete digital logic used to pre-fire and fire the [[tunnel diodes|tunnel diode]] pulser.
* [http://w140.com/tek_1502b_service.pdf Tektronix 1502B Service Manual (PDF)]
The later models (1502B/C) used a liquid-crystal display and a Z80 microprocessor.
* [http://w140.com/tek_1502c_service.pdf Tektronix 1502C Service Manual (PDF)]
Note that the manuals for the 1502B and 1503C are still available from Tektronix.


The other major difference between versions is the line charging method.
The 1502 uses a fast (36 ps) tunnel diode pulser, the later models used a half sine wave to charge the line. 
The TD pulser, with its Dirac delta edge, gives much better short range sensitivity, although it is much easier to destroy.
==Repair issues==
→ see [[1502/Repairs]]
==Replacement==
MOHR Test and Measurement manufactures a direct replacement to the 1502B and 1502C using an updated version of the same pulser/sampler. 
Any procedures or recorded waveforms are repeatable using the MOHR TDR.''[http://www.mohr-engineering.com/ct100 CT100B TDR Cable Analyzer]''.
==Links==
{{Documents|Link=1502}}
{{Documents|Link=1502B}}
{{Documents|Link=1502C}}
==Prices==
1979: $3,750 (~$16,200 in 2024 dollars)
According to an [[Media:Tek Schottky Diodes Memo rot.pdf|internal memo]], in 1979 annual sales were estimated at 543 units.
==Pictures==
'''1502'''
<gallery>
Tek1502-top.JPG|Top boards of the 1502
Tek1502-bottom.JPG|Underside of 1502 with stripline sampler and pulser exposed
Tek1502-samplinggate.JPG|Sampling gate near the BNC end of stripline
Tek1502-pulser.JPG|Pulser end of the stripline
Tek1502-td.JPG|Pulser TD removed from stripline
Tek1502-tdcurve.JPG|Pulser TD curve traced with a 576
TEK1502-HV-board-top.jpg|HV board top view
TEK1502-HV-board-bottom.jpg|HV board bottom view
Tek 1502 with printer.jpg|Tek 1502 with printer
Tek 1502 trace no connection.jpg
1502_Front_metric_version.jpg|Tek 1502 Metric Version (Option 5)
</gallery>
'''1502B'''
<gallery>
<gallery>
Image:Tek1502-top.JPG|Top boards of the 1502
Tek 1502b 1.jpg|1502B
Image:Tek1502-bottom.JPG|Underside of 1502 with stripline sampler and pulser exposed
Tek 1502b 2.jpg|1502B
Image:Tek1502-samplinggate.JPG|Sampling gate near the BNC end of stripline
Tek 1502b 3.jpg|1502B
Image:Tek1502-pulser.JPG|Pulser end of the stripline
Tek 1502b 4.jpg|1502B
Image:Tek1502-td.JPG|Pulser TD removed from stripline
Image:Tek1502-tdcurve.JPG|Pulser TD curve traced with a 576
</gallery>
</gallery>


==Components==
{{Parts|1502}}
{{Parts|1502B}}
{{Parts|1502C}}


[[Category:Time-domain reflectometers]]
[[Category:Time-domain reflectometers]]

Latest revision as of 03:53, 5 July 2024

Tektronix 1502
Time Domain Reflectometer
Tektronix 1502 Time Domain Reflectometer (CRT version)

Produced from 1975 to (?)

Manuals
Manuals – Specifications – Links – Pictures

The Tektronix 1502 is a series of Time Domain Reflectometers which replaced the 1501 in 1975. The 1502 is for high resolution, sister model 1503 for long range.

They are commonly used to test coaxial cables, although they have many other uses. The US military was a major purchaser, therefore most of the first series (the 1502, no letter) will be found surplus with some sort of US military property ID tag and an NSN sticker.

Hans Geerling did most of the circuit design on the 1502.

Key Specifications

  • please add

Internals and version differences

The first version used a CRT and is an almost completely analog design except for some discrete digital logic used to pre-fire and fire the tunnel diode pulser. The later models (1502B/C) used a liquid-crystal display and a Z80 microprocessor.

The other major difference between versions is the line charging method. The 1502 uses a fast (36 ps) tunnel diode pulser, the later models used a half sine wave to charge the line. The TD pulser, with its Dirac delta edge, gives much better short range sensitivity, although it is much easier to destroy.

Repair issues

→ see 1502/Repairs

Replacement

MOHR Test and Measurement manufactures a direct replacement to the 1502B and 1502C using an updated version of the same pulser/sampler. Any procedures or recorded waveforms are repeatable using the MOHR TDR.CT100B TDR Cable Analyzer.

Links

Documents Referencing 1502

Document Class Title Authors Year Links
Tekscope 1975 V7 N2.pdf Article Two Weatherproof TDR Cable Testers for Field Use Ivan Ivanov 1975 1502 • 1503
Tekscope 1975 V7 N3.pdf Article New Products 1975 5444 • 1502 • 1503 • 455 • E4010 • E4010-1 • 4923 • 2701 • 2703 • J6523 • WP1205
TekWeek (partial) October 10, 1975.pdf Article Spectrum analyzers require high technology Thor Hallen • Dave Friedley 1975 Spectrum Analyzers • Pentrix • 7L5 • 5L4 • 7L12 • 7L13 • 1401 • 491 • 1405 • 1502 • 1503

Documents Referencing 1502B

(no results)

Documents Referencing 1502C

(no results)

Prices

1979: $3,750 (~$16,200 in 2024 dollars)

According to an internal memo, in 1979 annual sales were estimated at 543 units.

Pictures

1502

  • Top boards of the 1502

    Top boards of the 1502

  • Underside of 1502 with stripline sampler and pulser exposed

    Underside of 1502 with stripline sampler and pulser exposed

  • Sampling gate near the BNC end of stripline

    Sampling gate near the BNC end of stripline

  • Pulser end of the stripline

    Pulser end of the stripline

  • Pulser TD removed from stripline

    Pulser TD removed from stripline

  • Pulser TD curve traced with a 576

    Pulser TD curve traced with a 576

  • HV board top view

    HV board top view

  • HV board bottom view

    HV board bottom view

  • Tek 1502 with printer

    Tek 1502 with printer

  • Tek 1502 Metric Version (Option 5)

    Tek 1502 Metric Version (Option 5)

1502B

  • 1502B

    1502B

  • 1502B

    1502B

  • 1502B

    1502B

  • 1502B

    1502B

Components

Some Parts Used in the 1502

Part Part Number(s) Class Description Used in
152-0335-01 152-0335-01 Discrete component 150 ps step recovery diode 1502 • S-2 • S-4 • S-6
154-0667-00 154-0667-00 • 154-0667-01 • 154-0667-02 • 154-0667-03 CRT CRT 1502 • 1503 • 305 • 326
SMTD995 152-0140-01 Discrete component 10 mA, 8 pF tunnel diode 1S1 • 1S2 • 1502 • 21A • 22A • 3T5 • 3T6 • 475 • 475A • 475M • 544 • R544 • 546 • RM546 • 547 • RM547 • 556 • R556 • 581A • 585A • RM585 • 7B52 • 7B53N • 7B70 • 7B71 • 7D10 • 7D11 • 7T11 • 7T11A • R7912 • S-51 • S-52 • TU-5 • 067-0572-00 • 067-0572-01 • 067-0681-00


Some Parts Used in the 1502B

Part Part Number(s) Class Description Used in
SG3524 156-0933-00 • 156-0933-01 • 156-1585-00 • 156-1585-01 Monolithic integrated circuit PWM switch-mode controller 067-1011-00 • 1502B • 1502C • 1503B • 1503C • 7A42


Some Parts Used in the 1502C

Part Part Number(s) Class Description Used in
SG3524 156-0933-00 • 156-0933-01 • 156-1585-00 • 156-1585-01 Monolithic integrated circuit PWM switch-mode controller 067-1011-00 • 1502B • 1502C • 1503B • 1503C • 7A42
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