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Tektronix 7CT1N
Curve tracer plug-in
Tektronix 7CT1N

Compatible with 7000-series scopes

Produced from 1971 to 1990

Manuals – Specifications – Links – Pictures

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

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 x1000 mode to detect leakage currents (of typical 1970s semiconductors, anyway).


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 (x 1 mode)
  • 10 nA/Div to 20 μA/Div, 1-2-5 steps (x 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/Div to 1 V/Div in 1-2-5 sequence, 1 kΩ current limit
DUT connection Three 4 mm jacks / binding posts
DUT adapters


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 Price 2015 value
1971 $400 $2,320
1980 $1,000 $2,870
1990 $2,100 $3,790