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Tektronix Type G
20 MHz differential amplifier
Type G front view

Compatible with 500-series scopes

Produced from 1955 to 1971

Manuals – Specifications – Links – Pictures

The Tektronix Type G is a plug-in differential amplifier for 500-series scopes. It was designed by John Kobbe.

Unlike the Type D, the Type G is optimized for RF, achieving only a 100 to 1 common-mode rejection ratio but maintaining it all the way to 20 MHz. Unlike "comparator" plug-ins such as the Type W and Type Z, the Type G does not contain an internal precision variable voltage source. It is for measuring the difference between two externally applied input signals. Its maximum sensitivity is 50 mV/div. It has seven tubes. (The early, slower 53G has five tubes.)

Its name changed twice. Type 53G was introduced in March 1955 along with the 541/545, but it was only specified to 10 MHz in a 535, and its performance in a fast mainframe was not documented. When the mainframe cabinet styles were revamped in August 1956, the Types 53A, 53B, 53C and 53G were all upgraded (sped up) and renamed; Type 53G became Type 53/54G. It was the only early plug-in that did not go through the awkward "53x/54x" phase. In 1959 it became Type G with no further change in design. It was dropped after 1970.

K, L, and T are tied for longest production life, at 16 years. B, D, and G are next at 15 years.

Types G and K are the only letter-series plugins where the Gain vernier is not concentric with the step attenuator.

Key Specifications

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Documents Referencing G

Document Class Title Authors Year Links
IBM 223-6725-2.pdf Application Note Tektronix oscilloscopes (IBM Customer Engineering Manual) 1960
Tekscope 1972 V4 N5 Sep 1972.pdf Article A Practical Approach to Differential Amplifiers and Measurements Fred Beckett 1972
Tekscope 1972 V4 N6 Nov 1972.pdf Article Differential Amplifiers and Measurements, Part 2 Fred Beckett 1972



Some Parts Used in the G

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
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
6AK5 154-0014-00 154-0206-00 154-0084-00 Vacuum Tube (Pentode) RF pentode B C CA G K L ML S Z 517 517A 524