The Tektronix 7CT1N is a curve tracer plug-in for 7000-series scopes. The 5CT1N plug-in for 5000-series scopes is very similar.

Tektronix 7CT1N
Curve tracer plug-in
Tektronix 7CT1N

Compatible with 7000-series scopes

Produced from 1971 to 1990

(All manuals in PDF format unless noted otherwise)

It can be installed in either a vertical or a horizontal compartment, a front-panel switch must be set accordingly. A pull-out cable with a plastic BNC plug connects to the input of a module installed in the corresponding plugin for the other axis, with a fixed 100 mV/div scaling compatible with time base X inputs.

Internally, a variable-amplitude 55 Hz triangle-wave source supplies a transformer to step up the drive voltage and decouple it from ground (Emitter terminal). A step source supplies base current or gate voltage to the DUT.

The amplifier for the current axis can be switched into a ÷1000 mode to detect leakage currents (of typical 1970s semiconductors, anyway).

Key Specifications

DUT drive voltage (C-E)
  • positive (NPN or N-channel) or negative (PNP or P-channel) half-waves
  • 7.5 V, 0.5 V/div, 240 mA peak
  • 30 V, 2 V/div, 60 mA peak
  • 75 V, 5 V/div, 24 mA peak
  • 300 V, 20 V/div, 6 mA peak
  • HV warning light on for > 50 V
  • peak power 500 mW
DUT current display
  • 10 μA/div to 20 mA/div, 1−2−5 steps (×1 mode)
  • 10 nA/div to 20 μA/div, 1−2−5 steps (÷1000 mode)
Base/Gate drive
  • 0 to at least 10 steps
  • dual polarity
  • variable offset, at least +/− 5 steps
  • current mode: 1 μA/step to 1 mA/step in 1−2−5 sequence
  • voltage mode: 1 mV/step to 1 V/step in 1−2−5 sequence (via 1 kΩ current limiting resistor)
DUT connection Three 4 mm jacks / binding posts
DUT adapters


Documents Referencing 7CT1N

Document Class Title Authors Year Links
Tekscope 1971 V3 N5 Sep 1971.pdf Article New Products 1971
Tekscope 1972 V4 N6 Nov 1972.pdf Article Oscilloscope to Curve Tracer with One Plug-in Matt Zimmerman 1972
48W-3346-3.pdf Brochure Making the Correct Semiconductor Measurements Time After Time 1982

Documents Referencing Curve tracers

Document Class Title Authors Year Links
062-1009-00.pdf Book Measurement Concepts: Semiconductor Device Measurements John Mulvey 1969
Tekscope 1969 V1 N1 Feb 1969.pdf Article Curve Tracing Displays 1969
Tekscope 1969 V1 N5 Oct 1969.pdf Article Troubleshooting the Sweep Ciruits Charles Phillips 1969
Tekscope 1972 V4 N3 May 1972.pdf Article Semiautomatic Testing with the Curve Tracer Jack Millay 1972
Tektronix Curve Tracers - Device Testing Techniques.pdf Book Tektronix Curve Tracers - Device Testing Techniques 1985

Common Problems

C30 and C32 (100 μF, 25 V) are under-rated and therefore have a tendency to leak or short, causing associated resistors R30 and R32 (240 Ω, 0.25 W, 5%) to overheat and fail. C30 and C32 should be replaced with modern equivalents rated above 35 V.


Year 1971 1980 1990
Catalog Price $400 $1,000 $2,100
In 2023 Dollars $3,000 $3,600 $4,900