515

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The Tektronix 515 is a 15MHz single-trace all-tube oscilloscope introduced in 1955. It does not use plug-ins. A rackmount version, the RM15 was also sold. There is also a 515A. The HV power supply uses tree 5642 rectifiers to produce +2325V for the CRT anode and -1675V for the CRT cathode. The LV power supply is linear, using a 6080 tube as the pass tube of the series regulator for +300V and +100V supply. The -150V supply is regulated by a 6AU5 tube. The voltage reference for the -150V 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.

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.

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

The 515 and 515A use the T55 CRT CRT. P31 phosphor was standard.

Serial numbers 101 through 1000 are "Type 515". Starting with serial number 1001, they are "Type 515A".