7A29

From TekWiki
Jump to navigation Jump to search
Tektronix 7A29
1 GHz amplifier
7A29 front view (sans options)

Compatible with 7000-series scopes

Produced from 1978 to 1991

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

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.

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 7000 series digitizers and the 7854 only.

The 7F10 uses the 7A29's amplifier board after the optical/electrical converter.

Key Specifications

Bandwidth 1 GHz (in 7104)
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)
Max. input max. 10 VRMS or 1 Ws pulses not exceeding 50 V; max. 100 V additional DC component in AC mode
Deflection 10 mV/div to 1 V/div, 1-2-5, ±2%; variable 2.5:1
Channels Single channel
Recommended probes P6056 (×10), P6057 (×100)
Options Option 4: variable delay (1 ns)

Links

Documents Referencing 7A29

Document Class Title Authors Year Links
Tekscope 1979 V11 N1.pdf Article 1 GHz at 1 mV in a General Purpose Plug-in Oscilloscope Hans Springer 1979
RISOM2873.pdf Article Improvement of the Bandwidth of the Transient Digitizers in the LIDAR Thomson Scattering Diagnostic on JET Erik Kristensen 1990

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

Year 1980 1985 1990
Catalog price $1,895 (Opt.04 +$350) $2,855 $3,775 (Opt.04 +$535)
In 2023 Dollars $7,100 (Opt.04 +$1,300) $8,100 $8,900 (Opt.04 +1,300)

Pictures

Internal

Schematics

Measurements

Components

Some Parts Used in the 7A29

Part Part Number(s) Class Description Used in
151-0261-00 151-0261-00 Discrete component dual PNP transistor AM501 AM502 CG5001 CG551AP FG501 FG502 FG503 OF150 OF151 OF152 OF235 OS261 RM502A R1140 R5030 R5031 R7912 067-0679-00 067-0807-00 1101 1140A 1141 1142 1350 145 1450 1480 1481 1482 1485 1501 1801 1900 1910 1980 213 26A1 26A2 2620 285 3A9 3A10 3S1 3S2 3S5 3S6 432 434 4501 454 4601 4602 4610 4612 4620 4632 4634 4701 475 492 492A 492AP 494 494P 496 496P 5A13N 5A20N 5A21N 5A22N 5A26 5L4N 502A 5030 5031 576 690SR 7A22 7A29 7B51 7B71 7J20 7L5 7S11 7S12 7912AD
155-0076-00 155-0076-00 Monolithic integrated circuit input protection and probe logic 465 485 7A29 7A29P 11A52 11A71 11A72 SCD1000
155-0175-00 155-0175-00 155-0175-05 Monolithic integrated circuit broadband amplifier 7904A 7912HB 7934 7104 R7103 7A29 7A29P 7F10 067-0587-02 067-0587-10 11A71 SCD1000 EG&G N-AM-173A
155-0180-00 155-0180-00 Hybrid integrated circuit fast input protection 7A29 7A29P 7F10 11A71
155-0181-00 155-0181-00 Hybrid integrated circuit input amplifier 7A29 7A29P 7F10 11A71