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Tektronix Type Z
Comparator preamp plug-in
Type Z front view

Compatible with 500-series scopes

Produced from 1960 to 1969


Manuals – Specifications – Links – Pictures

The Tektronix Type Z is a comparator plug-in for 500-series scopes, introduced in 1960 and dropped after 1968.

The Type Z has two inputs, A and B, plus a precision comparison voltage, VC, that is adjustable from 0 to ±1 V, 10 V, or 100 V via a ten-turn pot.

The following differential amplifier can be configured to display VA, −VB, VA−VB, VA−VC, or VC−VB.

This allows DC-coupled measurements of small signals with large DC offsets.

Unlike later comparators, Type Z has separate step attenuators for each input, permitting the user to view the difference between signals of widely differing amplitudes. Unfortunately the divider resistors have no trim, so CMRR is poor except at 50mV/div.

It is also the only comparator that can handle ±100 V common mode at full sensitivity.

With a pair of "Disconnect Signal" buttons, the Type Z was the first movement toward a "GND" position on the input switches.

The Type P6023 probe with R and C compensation, introduced in 1962, was specifically designed for the Type Z but also marketed for the Type G.


Maximum sensitivity is 50 mV/div, and common-mode rejection is 40,000:1 "from DC through audio frequencies".

Risetime as a general-purpose amplifier is 27 ns (13 MHz bandwidth). A side effect of Type Z's unprecedented dynamic range is that transient response is a function of signal amplitude: slew rates faster than 1V in 6ns will cause distortion due to grid current.


The Type Z uses both tubes and transistors, capitalizing on the strengths of each.

The step attenuators are turret attenuators.


  • $525 in 1962 ($4,750 in 2021 dollars)




Some Parts used in the Z

Page Class Description Used in
12AU6 Vacuum Tube (Pentode) RF pentode 112 512 556 575 545 549 581 585 C G K H L M Z
6AK5 Vacuum Tube (Pentode) RF pentode B C CA G K L S Z 517