1A5

The Tektronix Type 1A5 is a differential amplifier plug-in for 500-series scopes. It was designed by Bill DeVey after consultation with John Kobbe.

Manuals – Specifications – Links – Pictures

It has an Amphenol 165 series connector on the front panel for direct connection of the Type P6046 Active Differential Probe.

Type 1A5 was introduced in 1967, replacing Types W and Z, and lasted until the end of the 500-series scope line.

Key Specifications

Bandwidth	50 MHz down to 5 mV/div, 40 MHz at 1 mV/div
Deflection	1 mV/div to 20 V/div, 1−2−5
Common-mode rejection	20,000:1 from DC to 100 kHz, 10,000:1 up to 1 MHz, 200:1 at 20 MHz

Like most Tektronix differential plug-ins, the 1A5 has three modes: V_A−V_C, V_A−V_B, and V_C−V_B.

V_C is controlled by a ten-turn potentiometer and can vary from −5 V to +5 V (0.5 V on the 5 V/div to 20 V/div ranges).

Links

Documents Referencing 1A5

Document	Class	Title	Authors	Year	Links
Service Scope 43 Apr 1967.pdf	Article	New From Tektronix, Inc. In 1967		1967	568 • 230 • 454 • 647A • C-40 • 1A4 • 1A5 • 3L5 • 200-1
Tekscope 1969 V1 N4 Aug 1969.pdf	Article	Measuring Return-Loss	Charlie Rhodes	1969	1A5 • R140 • 528 • R520 • RM529
Tekscope 1970 V2 N5 Oct 1970.pdf	Article	Amplitude Measurement to Better Than 1%		1970	1S1 • 7503 • 7A13 • 1A5 • W • 3A7
Tekscope 1972 V4 N5 Sep 1972.pdf	Article	A Practical Approach to Differential Amplifiers and Measurements	Fred Beckett	1972	112 • 11A33 • 1A5 • 1A6 • 1A7 • 1A7A • 26A2 • 3A9 • 5A22N • 7A13 • 7A22 • AM502 • D • E • G • P6055 • P6046 • W • Z
Tekscope 1972 V4 N6 Nov 1972.pdf	Article	Differential Amplifiers and Measurements, Part 2	Fred Beckett	1972	112 • 11A33 • 1A5 • 1A6 • 1A7 • 1A7A • 26A2 • 3A9 • 5A22N • 7A13 • 7A22 • AM502 • D • E • G • P6055 • P6046 • W • Z

Patents that may apply to 1A5

Page	Title	Inventors	Filing date	Grant date	Links
Patent US 3187118A	Electrical switch having means for interconnecting concentric switch shafts	Marlow Butler • Oz Svehaug	1962-01-18	1965-06-01	11B2 • 1A5

Internals

The 1A5 is solid-state except for a pair of 7586 nuvistors used in the upper half of a cascode in the second amplifier stage.

The attenuator switching is mechanically complex. A gear mechanism drives the input attenuator switch (under the internal cover) selecting attenuators ×1000 (20 V/div to 5 V/div), ×100 (2 V/div to 500 mV/div), ×10 (200 mv/div to 50 mV/Div) or no attenuators (20 mV/Div to 1 mV/div).

Additionally, in the 500 mV/div and 50 mV/div positions, the operator can pull the V/Div knob outward when switching to one of the next two more sensitive ranges, in which case the higher attenuator (and higher input and comparison voltage range) remains in place.

Pictures

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Interior

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  Left side (attenuator cover removed)

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  Output board (left side) with HF Comp. daughterboard removed to show reed relays

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  Right side

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  Left side (attenuator cover in place)

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  Right side

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  Top

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  Top

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  Bottom

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  Rear

Switches detail

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Components