Tektra Model 146 — phosphor storage oscilloscope
Vertical · per division
Horizontal & trigger
Channels
| Source | Vpp | Vrms | Freq | Rise | Duty | State |
|---|---|---|---|---|---|---|
| CH1 — bench ref | 2.04 V | 721 mV | 19.98 kHz | 1.8 µs | 50.1 % | Locked |
| CH2 — gate drive | 4.96 V | 2.48 V | 9.99 kHz | 84 ns | 33.4 % | Overshoot |
| CH3 — ripple probe | 186 mV | 52 mV | 120.0 Hz | — | — | Muted |
| MATH — CH1 − CH2 | 5.61 V | 1.92 V | 9.99 kHz | 102 ns | 41.7 % | Derived |
Bench logbook
Field notes from the Tektra applications lab. Each entry ships with the captured trace, exported straight off the storage tube.
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04 · 11 · 26
14:07:22Chasing a 300 kHz whistle through a linear supply
The ripple was not ripple. Persistence set to infinite for ninety seconds revealed a second envelope walking slowly across the screen — a beat between the switcher and the reference clock on the daughter card.
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02 · 11 · 26
09:41:03Why your probe ground lead is an antenna
Six inches of spring-clip lead added 900 mV of apparent overshoot to a perfectly clean gate edge. We repeated the capture with a ground spring and the artefact vanished — the scope was honest, the connection was not.
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28 · 10 · 26
17:55:10A graticule is a promise, not a decoration
Ten divisions across, eight down, with the centre lines weighted heavier so the eye can read amplitude without counting. Everything on this instrument — including its type — is measured in divisions.
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21 · 10 · 26
11:12:47Single-sweep discipline for one-shot faults
Intermittents do not repeat on demand. Arm on a rising edge just below the fault threshold, walk away, and let the phosphor hold the evidence until morning. The 146 will still be showing it.
Calibration dispatch
One letter a month: a captured trace, the fault behind it, and the measurement that settled the argument. Written by the people who service these instruments.