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The Tektronix 7A29 is a single-channel vertical plug-in for | {{Plugin Sidebar | ||
[[7000-series scopes]]. | |manufacturer=Tektronix | ||
the [[7103]] and [[7104]] | |series=7000-series scopes | ||
|type=7A29 | |||
|summary=1 GHz amplifier | |||
|image=Tek 7A29 front 1.jpg | |||
|caption=7A29 front view (sans options) | |||
|introduced=1978 | |||
|discontinued=1991 | |||
|designers=John Addis;Val Garuts | |||
|manuals= | |||
* [[Media:070-2320-00.pdf|7A29 Instruction Manual]] (OCR) | |||
}} | |||
The '''Tektronix 7A29''' is a 1 GHz single-channel vertical plug-in for [[7000-series scopes]]. | |||
It is primarily intended for the [[7103]] and [[7104]]. | |||
The 7A29 | Like with the [[7A19]], a variable signal delay was available as an option. | ||
The 7A29 was designed by [[John Addis]]. | |||
There is also a [[7A29P]], which has digitally programmable gain, | |||
intended for the [[:Category:7000 series digitizer mainframes|7000 series digitizers]] and the [[7854]] only. | |||
The [[7F10]] uses the 7A29's amplifier board after the optical/electrical converter. | |||
{{BeginSpecs}} | |||
{{Spec | Bandwidth | 1 GHz (in [[7104]]) }} | |||
{{Spec | Input impedance | 50±1 Ω, VSWR <1.2:1 from DC to 1 GHz (10 mV/Div: 1.4:1, Opt.4: 1.5:1) }} | |||
{{Spec | Max. input | max. 10 V<sub>RMS</sub> or 1 Ws pulses not exceeding 50 V; max. 100 V additional DC component in AC mode }} | |||
{{Spec | Deflection | 10 mV/div to 1 V/div, 1-2-5, ±2%; variable 2.5:1 }} | |||
{{Spec | Channels | Single channel }} | |||
{{Spec | Recommended probes | [[P6056]] (×10), [[P6057]] (×100) }} | |||
{{Spec | Options | Option 4: variable delay (1 ns) }} | |||
{{EndSpecs}} | |||
==Links== | |||
* [http://www.eevblog.com/forum/testgear/tektronix-7a29-teardown/ Tektronix 7A29 teardown - nice detailed pictures of attenuator internals] | |||
* [https://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_amplifier/amplifier_7A29.htm Tek 7A29 @ amplifier.cd] including internal pictures | |||
* [https://youtu.be/yyg9qqE3JOk Tek 7A26 Lab Checkin] A special warning about permanent damage @ Zenwizard Studios | |||
{{Documents|Link=7A29}} | |||
==Internals== | |||
The 7A29 employs a number of Tek-made custom [[Hypcon]]-packaged hybrids, the [[155-0180-00]] | |||
fast input protection, [[155-0181-00]] input amplifier and [[155-0175-00]] trigger amplifier (2 ×). It also uses the [[155-0076-00]] input protection IC initially developed for the [[485]]. | |||
It uses a "feed-beside" scheme implemented with standard low-frequency operational amplifiers to | |||
compensate for low-frequency anomalies in the frequency response that are attributed to transistor heating (see [[Patent US 4132958A]]). | |||
The input connector is a special Tek-made part that is exactly 50 Ω. Typical BNC connectors are around 52 Ω. | |||
The 7A29 does not use the ±50 V supplies provided by the mainframe. | |||
Although the 7A29 has a VARIABLE gain control, this control has the undesirable side-effect of also affecting bandwidth. | |||
See bandwidth versus VARIABLE gain plot below. | |||
===Repair issues=== | |||
The input attenuator connected to the Volts/Div switch is very delicate. Three plastic levers actuate the ×2, ×10, and ×5 attenuator switches. Small metal rollers are clipped into the plastic levers and ride on cams. The plastic clips did not age well and have become very brittle. Combined with lack of lubrication on the metal rollers this often leads to broken plastic clips and missing rollers. Do not operate a stiff Volts/Div switch and lubricate rollers before use! | |||
==Prices== | |||
<!-- http://www.usinflationcalculator.com/ --> | |||
{| class="wikitable" | |||
|- | |||
! Year | |||
! 1980 | |||
! 1985 | |||
! 1990 | |||
|- | |||
! Catalog price | |||
|align=right| $1,895 (Opt.04 +$350) | |||
|align=right| $2,855 | |||
|align=right| $3,775 (Opt.04 +$535) | |||
|- | |||
! In 2023 Dollars | |||
|align=right| $7,100 (Opt.04 +$1,300) | |||
|align=right| $8,100 | |||
|align=right| $8,900 (Opt.04 +1,300) | |||
|- | |||
|} | |||
==Pictures== | |||
<gallery> | |||
Tek 7A29 front 1.jpg | 7A29 (no opt.) front | |||
Tek 7a29 front.jpg | 7A29 Opt.4 front | |||
7a29 manual photo.jpg | photo of 7A29 from manual (standard and option 4 units) | |||
Tek 7a29 with gr-874 1.jpg|7A29 with GR-874 factory mod | |||
Tek 7a29 bw vs var gain.png|7A29 bandwidth versus variable gain | |||
</gallery> | |||
====Internal==== | |||
<gallery> | <gallery> | ||
7a29 left.jpg | 7A29 (no opt.), left side (fixed delay line) | |||
Tek 7a29 left.jpg | 7A29 Opt.4, left view (variable delay line enclosure above PCB) | |||
7a29 right.jpg | 7A29, right side | |||
7a29 protection relay 1.jpg | 7A29 input protection relay | |||
7a29 protection relay lever.jpg | 7A29 input protection relay lever | |||
7a29 conn.jpg | 7A29 backplane connector (stripline signal path) | |||
Tek 7a29 amps.jpg | 7A29 amplifiers | |||
Tek 7a29 right rear.jpg | 7A29, right side, rear | |||
Tek 7a29 right front.jpg | 7A29, right side, front | |||
Tek 7a29 with gr-874 2.jpg|7A29 with GR-874 factory mod | |||
Tek 7a29 with gr-874 3.jpg|7A29 with GR-874 factory mod | |||
</gallery> | </gallery> | ||
====Schematics==== | |||
<gallery> | |||
7a29 input amp schem.png | input amplifier schematic | |||
7a29 output amp schem.png | output amplifier schematic | |||
</gallery> | |||
====Measurements==== | |||
<gallery> | |||
7a29-rise.jpg | Sample 7A29 rise time measurement (Source: [[S-52]]) - 320 ps equiv. 1.09 GHz system bandwidth including [[7104]] mainframe | |||
</gallery> | |||
==Components== | |||
{{Parts|7A29}} | |||
[[Category:7000 series vertical plugins]] | |||