547

Manuals – Specifications – Links – Pictures

The Tektronix 547 is a 50 MHz scope that takes letter-series and 1-series plug-ins. It has two identical timebases and, when used with the 1A1, 1A2, or 1A4, has the ability to display one input with one time scale and another input with a different time scale. The effect is similar to a dual-beam scope assuming that the input signals are repetitive. This "Sweep Switching" feature differentiates the 547 from the 546.

The project lead for the development of the Tektronix 544, 546, and 547 was Bob Rullman.

Internals

Triggering

Triggering is done with tunnel diodes. The 'A' trigger is based on a 10 mA tunnel diode. Up to serial number 11889, it uses a TD253. From 11890 onward, it uses a 152-0140-01.

CRT

The 547 uses the Tektronix 154-0478-00 CRT.

HV Transformer

A common problem with 547s is the HV transformer. Rather than potting the HV transformer in wax, as was done up to that point, the 547's HV transformer was potted in epoxy. Unfortunately, this epoxy turned out to absorb moisture over time, particularly when used in humid climates. The moisture causes increased losses in the transformer. Excessive losses require the regulator to drive the 6AU5 input oscillator tube (V800) harder. Eventually, the drive circuit cannot supply enough power to keep the supply in regulation. The usual solution is to scavenge a replacement transformer from another scope. As a labor of love, hobbyists have been known to rebuild the HV transformers. This is discussed from time to time on the Yahoo TekScopes forum.

Vertical Amplifier

The 547 has a five-stage BJT vertical amplifier that is fully differential from the plug-in connector to the CRT vertical deflection plates. There is one tube in the vertical signal path, a 12AT7 acting as a unity-gain buffer between the plug-in connector and the vertical amplifier.

There is a 170 nanosecond delay line between the first and second gain stages.

Links

• Tek 547 in "Reading Jim Williams" blog: Scope Sunday 13 and Vintage Scopes are Better, pt.1
• "MightyOhm" blog: Jim Williams workbench
• Comparing an Apollo Era Workhorse to Today’s Bench Scope @ tek.com
• Eiki Martinson: Tektronix 547 Oscilloscope—Getting an Old Soldier Back in the Fight
• Tek 547 page @ amplifier.cd
• The Tektronix 547 Oscilloscope - Magic in the Box
• J.Evans's 547 page

Pictures

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  Front view

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  Top

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  Right

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  Left

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  Vertical amplifier

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  Trigger A

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  RM547

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  Gray 547