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Tektronix 2A60
1 MHz amplifier
2A60 front view

Compatible with 560-series scopes

Produced from 1962 to (?)

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

The Tektronix 2A60 is a 1 MHz, single-channel amplifier plug-in for 560-series scopes. It was designated "Type 60" before being renamed 2A60 at serial number 820.

The V/div positions of the 2A60 are somewhat unusual among Tektronix plug-ins. Most plug-ins use the 1−2−5 scale factors, e.g., 10 mV/div, 20 mV/div, 50 mV/div, 100 mV/div, etc. The 2A60's V/div positions are multiples of ten: 50 mV/div, 500 mV/div, 5 V/div, 50 V/div. This unusual feature was presumably a cost-cutting measure.

The 2A60 was the one of the least expensive amplifier plug-ins for 560-series scopes. (The Type 59 was even cheaper, at half the price of the 2A60.)

The 2A60 is similar to the 3A75, but the 3A75 has the standard 1−2−5 V/div positions and 4 MHz bandwidth. The linearization trick of diodes bypassing the cathode resistor (discussed below) is also used in the 3A75.

In the 1963 Tektronix catalog, both models were listed. The 3A75 was 1.7× the cost of the 2A60.

Key Specifications

Bandwidth 1 MHz
Rise time 350 ns
Deflection 50 mV, 500 mV, 5 V or 50 V per division, plus variable adjustment


The input signal passes through a compensated attenuator and then into the input amplifier, a differential amplifier formed from two 6AU6 pentodes. The differential signal is then applied to a cathode-follower stage which drives the output stage.

The output stage is a differential amplifier formed from both halves of a 6DJ8 dual-triode. To help linearize the output stage when it is making large positive or negative excursions, a pair of germanium diodes is placed in parallel with the resistor that connects the cathodes of output triodes. The effect is that when the signal swings far in either direction, the gain degeneration (negative feedback) is reduced. This helps keep gain stable across the range of signal voltages.


Some Parts Used in the 2A60

Page Class Description Used in
6AU6 Vacuum Tube (Pentode) RF pentode 2A60 80 107 160 181 190 310 310A 316 317 360 502 502A 511A 512 513 516 517 517A 524 526 529 RM529 531 531A 535 536 545 545A 546 547 549 555 575 581 581A 585 585A C CA Q
6DJ8 Vacuum Tube (Dual Triode) dual triode 80 132 161 310A 316 317 3A75 502 502A 503 504 515 516 519 526 529 RM529 533 535 536 543 544 545 545A 545B 546 547 549 555 556 565 581 581A 585 585A 661 2A60 63 2A63 3A7 3A8 1121 1A4 67 81 82 86 3B1 3B4 1S1 B O W Z Telequipment S32A Telequipment D52 Telequipment TD51 Telequipment S52 Telequipment S51 Telequipment Type A