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Tektronix 515
15 MHz Tube scope
Tektronix 515 front

Produced from 1955 to (?)

Manuals – Specifications – Links – Pictures

The Tektronix 515 is a 15 MHz single-trace all-tube oscilloscope introduced in 1955. It does not use plug-ins.

A rack-mount version, the RM15 was also sold. There is also a 515A (serial numbers 101 through 1000 are "Type 515", 1001 and upward are "Type 515A").

The 515A has a Z-axis input and slightly higher vertical sensitivity than the 515. Maximum vertical sensitivity is 100 mV/Div for the 515 and 50 mV/Div for the 515A. The 516 is essentially a dual-trace version of the 515.

The 515 and 515A are fan-cooled, both in benchtop and rackmount forms.


Channels One vertical channel (two input connectors and a switch to select)
Bandwidth DC to 15 MHz
Rise time 23 ns
Deflection 50 mV/div to 20 V/div (515A), 100 mV/div to 50 V/div (515)
Sweep 0.2 μs/div to 2 s/div
CRT T55 CRT CRT, P31 phosphor standard, 6 cm linear vertical deflection
Input impedance 1 MΩ // 30 pF
Power consumption 275 W
Weight 40 pounds (18 kg)



The HV power supply uses three 5642 rectifiers to produce +2325 V for the CRT anode and -1675 V for the CRT cathode. The LV power supply is linear, using a 6080 tube as the pass tube of the series regulator for +300 V and +100 V supply. The -150 V supply is regulated by a 6AU5 tube. The voltage reference for the -150 V supply is a 5651 tube. The 515 and 515A use selenium rectifiers. A kit was later made available for converting them to silicon rectifiers for improved reliability. Starting at serial number 4424, the 515A used the 120-142 power transformer, the same part that is used in the 516.

The vertical amplifier is fully differential, DC-coupled, and all tube. The stages are as follows:

  • input buffer, cathode followers, 6AU6
  • first gain stage, differential amplifier, T-coil, 12BY7
  • unity gain buffer, cathode follower, 6DJ8
  • output amplifier, differential amplifier, T-coil, 6CL6

The horizontal amplifier uses half of a 6DJ8 as a buffer, followed by a 6DJ8 as a differential amplifier and phase splitter, followed by the two halves of another 6DJ8 as the output cathode followers driving the horizontal CRT deflection plates.

The trigger is a 6DJ8 differential trigger amplifier followed by a 6DJ8 Schmitt trigger.


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