From TekWiki
Jump to navigation Jump to search
Tektronix Type (53)C
Dual-trace 8.5 (24) MHz amplifier
Tektronix Type C (later version)

Compatible with 500-series scopes

Produced from 1954 to 1959


Manuals – Specifications – Links – Pictures
Actually, there never was a Type C, but that name is sometimes used as shorthand for the official "Type 53C" and "Type 53/54C" nomenclatures.

The Tektronix Type 53C is a dual-trace plug-in for 500-series scopes. It was introduced along with the 531 and 535 mainframes in 1954. It is very possibly the first dual-trace scope or plugin ever.


In the 53x scopes (Tek never documented its performance in the 540's), its bandwidth is 8.5 MHz, and like most letter-series plug-ins, its maximum vertical sensitivity is 50 mV/div. Unlike the Type A and Type B, the Type C had the ability to invert the signal before display.

Type 53C was replaced by Type 53/54C in 1956 when the 541 and 545 were introduced. The Type 53/54C's bandwidth is 24 MHz in those scopes. In 1959 it was replaced by Type CA.


At 15 tubes, the Type 53/54C and Type CA have the highest tube count of any letter-series plug-in. Each channel consists of a 6AK5 cathode-follower driving a 12AU6 differential pair which drives a 6AU6 differential pair. The two channels converge on a 12AT7 cross-coupled cathode-follower. Four more tubes, a 6AL5 and three 12AT7's, comprise a logic circuit which determines which channel drives the output at any given moment. The options are A, B, CHOPPED, and ALT.



Some Parts used in the C

Page Class Description Used in
12AT7 Vacuum Tube (Double Triode) dual high-gain triode 180 315 360 502 513 513D 514D 514AD 514D 524D 529 RM529 544 546 547 556 M G K C A 3A2 1M1
12AU6 Vacuum Tube (Pentode) RF pentode 112 512 575 C G K H L M O Z
12AU7 Vacuum Tube (Double Triode) twin medium-μ triode 122 547 555 575 581 581A 585 585A C D 181 502
6AK5 Vacuum Tube (Pentode) RF pentode B C CA G K L S Z 517
6AU6 Vacuum Tube (Pentode) RF pentode 107 181 310 502 513 575 581 585 C CA