3A9
Template:Plugin Sidebar 2 The Tektronix 3A9 is a differential amplifier plug-in introduced in 1969 for 560-series scopes. It shares similarities with the 7A22 from the 7000 series and 26A2 (2600 series).
The 3A9 features a variable high-frequency cut-off from 100 Hz to 1 MHz and a variable low-frequency cut-off from DC to 10 kHz. When DC coupled, the 3A9 provides a variable offset voltage. The common mode rejection is 100,000:1.
Key Specifications
Bandwidth | 1 MHz, LF limit switchable DC, 0.1 Hz to 10 kHz in ×10 steps, HF limit switchable 100 Hz to 1 MHz in ×3/×10 steps |
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Deflection | 10 μV/Div to 10 V/Div in 1–2–5 sequence |
Input impedance | 1 MΩ // 47 pF (either input) |
Signal ranges |
Range | Differential signal | DC Offset | Common mode |
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10 μV/Div to 10 mV/Div | ±1 V | ±1 V | ±10 V |
20 mV/Div to 0.1 V/Div | ±10 V | ±10 V | ±100 V |
0.2 V/Div to 1 V/Div | ±100 V | ±100 V | ±500 V |
2 V/Div to 10 V/Div | ±1000 V | ±1000 V | ±500 V |
Internals
The differential amplifier design is a variant of the 1A7A circuit, also used with modifications in the 7A22, 5A22N, AM502 and 5030/5031 (26A2 too?).
The 3A9 provides differential high-impedance voltage inputs and an AC current probe input for use with, for example, the P6021 or P6019.
The front-end of the 3A9 starts with a differential pair formed by the two N-channel JFETs in, a 151-1027-00, Q133.
Pictures
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Preamp (front-end) schematic