517

The Tektronix 517 is a 50MHz scope introduced in 1950 or 1951. The power supply is an external box, like the 507, 551 and 555. The 517 does not take plug-ins. There is also a 517A. The 517 closely resembles a scope that Tektronix developed under a contract for the US military during 1949 and 1950.

The external power supply and oscilloscope are connected by a removable cable with Jones plugs on both ends. Units with serial numbers 101-1739 use a 12-pin Jones connectors; after that it is a 16-pin Jones connector. The voltages on the 12-pin connector are:

Pin 1: +750V, regulated
Pin 2: +475V, regulated
Pin 3: +350V, unregulated
Pin 4: +225V, regulated
Pin 5: +150V, regulated
Pin 6: Ground
Pin 7: -250V, regulated
Pin 8: +180V, unregulated

The 517 makes extensive use of the distributed amplifier concept. It was originally designed to use the 5XP CRT, which has 38V/cm vertical deflection sensitivity when operated with 24kV acceleration voltage. The vertical sensitivity at the input connector is 0.1V/cm. So the voltage gain is 380. For 4cm deflection, a 152-volt differential output swing is required. The vertical signal path is as follows:

Gain Stage 1: single-ended, six sections, distributed, 6AK5 pentodes
Gain Stage 2: single-ended, six sections, distributed, 6AK5 pentodes
Gain Stage 3: single-ended, seven sections, distributed, 6AK5 pentodes
Trig Pickoff: one common-cathode 6CB6 pentode
Signal Delay: 51 feet of RG63U 125-ohm coaxial cable
Phase Splitter: single-ended in, differential out, three sections, distributed, 6CB6 pentode
Gain Stage 4: differential, six sections, distributed, 6CB6 pentodes
Gain Stage 5: differential, twelve sections, distributed, 6CB6 pentodes

There is a trigger amplifier in the 517 which can its input from an external source, or from the trigger pickoff in the vertical pre-amp, or from the internal rate generator circuit. The trigger amplifier circuit has five stages:

Phase Splitter: 6J6 dual-triode connected as a differential amplifier
Gain Stage 1: single-ended, three sections, distributed, 6AK5 pentodes
Gain Stage 2: single-ended, three sections, distributed, 6AK5 pentodes
Gain Stage 3: single-ended, common-cathode, 6AG7 pentode
Gain Stage 4: single-ended, common-cathode, 6AG7 pentode

The 517 uses 24kV total acceleration voltage on the CRT. This is generated by the Type 420 High Voltage Power Supply subsystem in the 517. It uses a 1.8kHz oscillator to produce the high voltage, unlike other Tek scopes which use HV oscillators in the ultrasonic range.

The power consumption of a 517 is 1250 Watts. The indicator unit weighs 76 pounds and the external power supply weighs 72 pounds.

front
bottom internal
right internal
top internal
power supply internal
12-pin power connector

517

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