A

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Tektronix Type A
20 MHz amplifier plug-in
Tektronix Type 53A

Compatible with 500-series scopes

Produced from 1954 to 1962

Manuals

Alternate copies

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

The Tektronix Type A is a single-channel preamp introduced in 1954 for 500-series scopes. It provides two inputs and has a switch to select between them. A 545 with a Type A has a system risetime of 18 nanoseconds and a bandwidth of 20 MHz. It was designed by Bill Polits.

Although 1959 was the first year one could find a "Type A" in the catalog, the same instrument with earlier "Type 53/54A" nomenclature was in the August 1956 Short Form catalog, and its Type 53A ancestor was in the August 1954 catalog which introduced the first 500-series scopes, the 531 and the 535.

Type A was the first letter-series plug-in to be discontinued, in 1962. Customers were told to get Type B instead, although it cost more.

Key Specifications

  • please add

Bandwidth is 10 MHz in the 530 mainframes.

Catalogs don't list 53A performance in the 540 mainframes. The Factory Cal Procedure says 20 MHz, but this is wrong. (A Type 53A's measured 3 dB point was around 17 MHz while a Type A made 23 MHz. Furthermore, the front-panel artwork reads ".017 usec" for 53A and .015 for A.)

Internals

Type 53A has only three tubes, and no T-coils.

The plug-in uses a 12AU6 in the front end as a cathode follower. This input stage drives the second stage, a differential amplifier made of two more 12AU6 tubes.

The second stage drives the output stage, a pair of cathode followers made of both halves of a 12AT7 tube. The plate of each output tube is connected to the cathode of the other output tube by a 5 nF capacitor. This "cross-bootstrapping" extends the high-frequency response.

Pictures

Components

Some Parts Used in the A

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