M

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Tektronix Type M
20 MHz quad-channel amplifier
Type M front view

Compatible with 500-series scopes

Produced from 1962 to 1973

Manuals

Alternate copies

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

The Tektronix Type M is a four-channel plug-in for 500-series scopes that was introduced in 1962, along with the Type O, and dropped after 1972. It was designed by Oz Svehaug and Glenn Parks.

Early versions had UHF connectors, later versions have BNC connectors for the inputs.

Key Specifications

Bandwidth DC to 20 MHz
Rise time 17 ns
Deflection 20 mV/div to 10 V/div, 1–2–5
Modes Each channel can be AC or DC coupled, inverted or straight, or disabled entirely. The enabled channels can operate in CHOP or ALT mode.

Internals

Each input goes through a step attenuator, is clamped by a neon bulb, and then is fed to the grid of a cathode follower made with a 7586 Nuvistor tube. Next, the signal goes to a PNP differential amplifier. Diodes in series with the collector signal of this differential amplifier are used for input channel switching. An internal differential signal bus connects the switched outputs of each of the input channels and feeds the signal to the output amplifier, which drives pins 1 and 3 of the 500-series plug-in connector. The output amplifier is two 12AU6 pentodes connected as a differential amplifier, followed by a 12AT7 dual triode acting as a cathode follower to drive the output with a relatively low impedance.

Pictures

Components

Some Parts Used in the M

Part Part Number(s) Class Description Used in
12AT7 154-0039-00 Vacuum Tube (Dual Triode) dual high-gain triode 161 180 310 310A 315 316 360 502 502A 511A 512 513 513D 514 514AD 514D 516 524 529 RM529 544 546 547 556 565 570 3A2 75 3A75 1M1 A B C G H K L ML M N K R S Z Keithley 610B
12AU6 154-0040-00 Vacuum Tube (Pentode) RF pentode 81 112 1L10 1L20 1L60 3L10 512 556 575 545 547 549 581 585 A B C G K H L ML M N O R S Z
7586 154-0306-00 Vacuum Tube (Triode) Nuvistor triode M 1A1 1A2 1A5 10A2 10A2A 11B1 11B2A 321 321A 3A1 3A1S 3A3 3A5 3A6 3A7 3A8 3A74 3S76 3T77 3T77A 3B5 4S1 4S2 6R1 6R1A 9A1 9A2 82 86 S-311