7A18

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Tektronix 7A18
75 MHz dual channel amplifier
7A18 front view

Compatible with 7000-series scopes

Produced from 1971 to 1992

Manuals

Alternates

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

The Tektronix 7A18 is a general-purpose 75 MHz dual-trace vertical plug-in for 7000-series scopes. Model 7A18N is identical except it omits the readout circuits.

Option 06 (first offered in 1975 catalog) adds offset voltage controls giving ±200 Div offset range. This option replaces the IDENTIFY buttons with DC offset controls, and adds a fourth "DC offset" position to the input coupling switch.

The 200 MHz 7A26 and 400 MHz 7A24 share the same front panel layout and operation.

The 7A18 uses a discrete front-end followed by M36 channel switch ICs for the vertical and trigger signals.

Key Specifications

Input impedance 1 MΩ // 20 pF
Deflection 5 mV/div to 5 V/div in 1–2–5 sequence, 2%
Bandwidth 0 – 75 MHz (DC), 10 Hz – 75 MHz (AC)
Noise < 300 μV in 5 mV/Div
Option 06 offset range ±200 Div equiv. from ±1 V in 5 mV/Div range up to ±200 V in 1 V/Div range (above that limited by maximum input voltage)
Features
  • Mode: CH1 only, CH2 only, Add CH1+CH2, Alternating, Chopped. CH2 can be inverted.
  • Input sockets with contact ring for probe ×10 / identify information
  • No bandwidth limiter switch
Weight 1.4 kg

Links

Documents Referencing 7A18

Document Class Title Authors Year Links
Tekscope 1977 V9 N1.pdf Article Counter and Oscilloscope Combination Makes Difficult Measurements Emory Harry 1977

Prices

Year 1971 1976 1980 1984 1990
Catalog Price $535 $615 $915 $1,250 $1,790
In 2023 Dollars $4,100 $3,300 $3,400 $3,700 $4,200

Repair issues

Attenuator solder joints

The pins of the attenuator modules are connected to conductive traces on the ceramic substrate inside by low-temperature soldering, which can go bad. Re-seating the module can temporarily restore the internal contact but will usually not fix the problem permanently. Repair is possible by opening the click-locked lid and carefully resoldering.

Variable gain pots

These pots (R237A,B and R437A,B 315-0241-00) are bonded together - that bond can break which stops the gain push from working. Looking at a few 7A18s, I see that the design was changed at least once.

Pictures

Development Prototypes

7A18A

Option 06

Components

Some Parts Used in the 7A18

Part Part Number(s) Class Description Used in
155-0022-00 155-0022-00 155-0022-01 Monolithic integrated circuit analog multiplexer 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


Some Parts Used in the 7A18A

Part Part Number(s) Class Description Used in
155-0022-00 155-0022-00 155-0022-01 Monolithic integrated circuit analog multiplexer 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