549

The Tektronix 549 is the only storage scope that takes a letter-series or 1-series vertical plug-in. It was introduced in 1966 and discontinued in 1972. The vertical -3dB bandwidth is 30MHz.

Mix of Transistors of Tubes

Like many Tek scopes from the period, it uses a mix of transistors and tubes. For example, consider the buffer amplifier in the 549, whose purpose is to interface the high-impedance output of the plug-in with the low-impedance of the 200 nanosecond delay line in the 549. As is usual in oscilloscope vertical circuits, the requirement is to have flat frequency response from DC to the maximum frequency of the scope and to have linear phase response over this same frequency range. In the 549, this buffer is implemented as follows: A 6DJ8 tube configured as a cathode follower is used at the interface with the plug-in to present a high impedance to the plug-in. This input stage drives an NPN BJT differential amplifier, which operates at the bottom of a cascode configuration with a 7119 tube on top. The output of the cascode (the plate of the 7119) drives the delay line. Since the entire signal path is differential, the common-mode voltage does not have to be zero, and it is not; the differential signal in the delay line rides on 167 volts of DC. After the delay line, the signal enters another cascoded differential amplifier with NPN BJTs on the bottom and 8608 tubes on the top. The vertical deflection plates of the CRT are driven by the plates of a 8608 10-watt power pentode, through inductive matching/peaking networks.

Non-Distributed Amplifier

The 549 is slightly unusual among 54x-series scopes in that it does not use a distributed vertical amplifier. (Other exceptions include the 545B and 547).

Triggering

Triggering is done using an NPN BJT Schmitt trigger.

Storage

The screen has two storage targets, upper and lower, whose storage mode and erase signals can be controlled independently. There is a remote control cable/switch, part number 012-0102-00, that can erase the screen and reset the single sweep.

The 549 weighs 68 pounds and consumes 600 watts.

• 549 manual on BAMA
• Tektronix 549 in 1968 Catalog (PDF)

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  Front of a 549.

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  Vertical amp.

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  Top view.

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  Storage board.

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  Power supply behind door.

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  012-0102-00 remote control for 549