Я4С-91
The Я4С-91 is a dual timebase plug-in for Soviet 7000-series clones. It is roughly analogous to the Tek 7B53A. It features a 3И306К tunnel diode in the timebase A trigger circuit.
Significant differences to the 7B53A include:
- slowest sweep speed 50ms/div
- no x10 magnifier, direct access to 5ns/div speed
- timebase B always runs after timebase A and has no separate trigger
- timebase mode A+B actually display A intensified by B alternating with B
- delay time is set by a single-turn pot with a reduction drive, and it is not calibrated
- only timebase B has variable time/div
The external trigger connector is a СР50-73 type.
The example in the photos is labelled in German. A version labelled in Russian also exists.
Key Specifications
| Time/div | 50ms to 5ns |
|---|---|
| Trigger modes | norm, auto, single sweep |
| Trigger sources | internal, external, external/10, line |
Links
Pictures
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Front
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Threequarter view
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Left side internal
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Left side detail
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Timebase A PCB
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Tunnel diode in Timebase A trigger
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Right side internal
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Right side detail
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Timebase B PCB
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Output amplifier PCB
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Closeup of PCB construction
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Factory-added tape to insulate capacitors from side panel
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Cam-operated microswitch to select variable time/div
