545

Manuals – Specifications – Links – Pictures

The Tektronix Type 545 is a 30 (33) MHz scope that takes letter-series and 1-series plug-ins. It has two timebases, which allows delayed triggering.

Type 545 was introduced February 7th, 1955 along with the Type 541, and superseded in 1959 by the Type 545A, which was in turn superseded in 1964 by the Type 545B, which was produced until 1973. The difference between the 545A and 545 is the control ergonomics, not any major circuit design changes. However, the delaying timebase on the 545A supports delays up to 10 seconds while the 545 supports delays only up to 100 milliseconds.

The 545A uses the T5430 CRT. P2 phosphor was standard.

Versions

There were also rack-mount versions. Types RM41 and RM45 were introduced in October 1957, Types RM41A and RM45A were introduced in May 1959 simultaneously with their bench counterparts, and the rackmount Type RM545B or R545B was introduced at the same time as Type 545B.

Clones of the 545A are the Lavoie LA-265A and Hickok 1805A. These clones were not licensed by Tektronix.

Relationship of 545B to 547

Some feel that Type 547 replaced Type 545, but this is not quite true; Types 545B and 546/547 were introduced simultaneously. It is more correct to say that the 50 MHz 546 and 547 were upgrades. (The Type 544 is likewise the upgrade for the 541.)

The Type 53K/54K plug-in was introduced with the 545 and 541, and until Type 53/54L came out in 1957, it was the only plug-in that could take full advantage of their bandwidth. There was never a full-speed dual-trace plug-in — that would wait until Types 1A1 and 1A2, which came out with the 545B.

Key Specifications

Bandwidth	30 MHz (33 MHz with a 50 MHz plug-in such as Type 1A1)

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Internals

Early 545 units have selenium rectifiers. Later units have silicon rectifiers.

The trigger circuit used a 6DJ8 tube in the 545 and 545A. NPN transistors are used in the 545B trigger circuit.

545 and 545A Vertical Path

Types 545 and 545A have a six stage differential distributed vertical amplifier made of twelve 6DK6 tubes. The vertical amplifier used in the 545A is also used in the 551 and 555. The 545 uses the 154-098 CRT. With the limited CRT technology available at the time, the higher bandwidth of the 541 and 545 came with a tradeoff. The vertical scale is only 4 divisions, 2 above and 2 below the graticule center line. The lower bandwidth 531 and 535 retained the 6 vertical divisions, as used in most other Tektronix scopes. In the 545, the distributed vertical amplifier's plate supply was not separately fused. Shorting the outputs of the vertical amplifier to ground can cause major damage. In the 545A, there is a 150 mA fuse, F1054, preventing such damage.

545B Vertical Path

The Type 545B differs significantly from the 545 and 545A. It has a partly solid-state, non-distributed vertical amp, and uses the 154-0478-00 CRT which is also used in the 544, 546, and 547. Improvements in CRT design, including reduced deflection plate capacitance and increased sensitivity increased the vertical scale in the 545B from 4 to 6 divisions. The improved CRT also uses a ceramic envelope, with flat glass faceplate that has internal graticule markings, eliminating parallax errors.

Ken Chorney says:

Just wanted to add an alternative supplier for replacement fan mounts for the Tektronix 545 oscilloscope fan. Digi-Key currently stocks two part numbers which fit and work perfectly: RPC1597-ND and EAR1345-ND. Both are 1/2" length (same as original) and both have 8-32 male threaded ends (same as original). Both are slightly smaller in diameter (0.4" vs. the 0.5" originals) but this does not affect their fit at all and likely does not affect their function appreciably. I have installed three of the RPC1597-ND standoffs in my 545 and they fit and work perfectly.

Links

• J.Evans' 545A page / 545B page
• radiomuseum.org: 545 / 545A / 545B
• Richard Sears: Tektronix 535A and 545A
• barrytech.com: 545 / 545A / 545B

Pictures

545

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  545, early style

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  545, early style

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  545, early style

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  545, early style

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  545, early style

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  545, early style

545A

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  545A front

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  545A Delay line

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  545A block diagram

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  545A signal path

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  545A trace

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  545A handbook compartment

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  545A handbook compartment

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  545A on a Tek 202-1 cart

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  545A controls

RM45A

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  RM45A, standard color

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  RM45A rear

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  Brown-face RM45A

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  RM 45A with standard B timebase

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  RM 45A with raster B timebase, MOD 116B

545B

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  545B front

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  545B with Type M plug-in

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  545B right side

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  545B with 1A1

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  545B signal path

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  545B top

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  545B rear

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  545B right internal

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  545B vertical output stage

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  545B vertical output stage

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  545B Block Diagram

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  545B Power Supply

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  545B High Voltage Power Supply

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  545B Calibrator

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  545B Trigger A

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  545B Timebase A

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  545B Trigger B

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  545B Timebase B

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  545B Horizontal Amp

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  545B with 1S2

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  545B left internal

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  545B right internal

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  545B left external

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  545B right external

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  545B top external

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  545B Squarewave

RM545B

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  RM545B