524

The Tektronix 524AD is a monolithic oscilloscope introduced in 1953 for monitoring television waveforms, designed by Cliff Moulton.

Manuals – Specifications – Links – Pictures

In a 1972 interview, Charlie Rhodes recalled:

In 1953 Cliff Moulton re-designed the 514 for TV station needs. This became the 524, the first TV-oriented instrument. It looked like a market of 200 or so in those days, but wound up producing 10,000 of this model.

Interestingly, the 524 appears on page 31 of the 1966 RCA Test Equipment Catalog.

Key Specifications

Bandwidth	DC to 10 MHz @ ≥150 mV/div; with preamp, 2 Hz to 10 MHz down to 15 mV/div
Rise time	40 ns
Deflection	variable from 15 mV/div to 50 V/div
Input	1 MΩ // 45 pF; 10 MΩ // 15 pF with P510A ×10 probe
Sweep	100 ns/div to 10 ms/div, ×3 and ×10 magnifier
Time markers	1 μs, 100 ns, 50 ns, 318 ns, 1.59 μs (200 or 40 markers per TV line)
CRT	5ABP1 (P1 phosphor) standard, P7 and P11 optional; 4 kV total acceleration (−1.5 kV/+2.5 kV)
Power	500 W
Weight	27.7 kg / 61 lbs

It uses selenium rectifiers in the low-voltage power supply.

The 524AD has a 56°C/133°F thermal cutoff.

Links

• Tektronix Photo Manual 1952

Internals

The vertical signal path of the 524 is similar to that of the 514. They have similar front-ends and similar distributed vertical output amplifiers.

The vertical amplifier has a three-stage distributed amplifier section (6×6AG7).

The video trigger circuitry present in the 524 distinguish it from the 514. Just before the L-C delay line in the vertical signal path, there is a cathode follower, V15A, that serves as the trigger pickoff buffer. The resulting trigger signal goes to a video sync separator circuit. Here, the there is clamping and amplification and, most importantly, a non-retriggerable multivibrator. The multivibrator is triggered by the vertical sync of the NTSC waveform. After being triggered, it is not triggerable again for about about 25 ms, so it misses the vertical sync of the next interlaced field and instead triggers on the vertical sync of one following that. So it consistently shows the "even" field or the "odd" field. There is a switch that perturbs the multivibrator so it can be switched between even and odd fields. The video trigger circuit drives a conventional trigger circuit and sweep circuit similar to that of the 514.

The 524 uses a cylindrical style of ceramic terminal strip, which is less common than the straight style. The cylindrical style is also used in the Type C, Type CA, and 315.

Pictures

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  Displaying a squarewave

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  Marker switch

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  Unusual round terminal strips in the 524

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  Top right internal view

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  Selenium rectifier and unusual fan mount

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  Time Mark Gen for 524

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  Sync Separator

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  Bottom front, power supply circuitry

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  Bottom rear, transformer wiring

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  Cartoon in 1960 version of circuit diagrams

Early model

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Components