The Tektronix 7A22 is a single channel differential vertical amplifier for the 7000 series mainframes, designed by Val Garuts and produced from about 1969 to 1991. Specifications and controls are similar to the 26A2 and the 3A9 from the 560 series but without current probe input or front panel signal output.
The 7A22's input sensitivity reaches down to 10 μV/Div. Bandwidth is 1 MHz, the upper 3 dB limit can be reduced in ×3 steps down to 100 Hz (to eliminate noise, inter alia), and the lower bandwidth can be raised in ×10 steps from 0.1 Hz to 10 kHz. A separate control optionally supplies an internal DC voltage to offset the DC signal component. Even in the most sensitive ranges (10 μV/Div to 10 mV/Div), common-mode voltage can be ±10 V. Input resistance is 1 MΩ, but for high source resistance DC coupled measurements, one can disconnect the internal gate return resistors of the input FETs, at the disadvantage of disabling the 20 mV/div and higher ranges.
Applications include audio, biological signals, sensors etc.
|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|
|Deflection||10 μV/Div to 10 V/Div in 1–2–5 sequence|
|Input impedance||1 MΩ // 47 pF (either input)|
|Range||Differential signal||DC Offset||Common mode|
|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|
The 1A7A (designed by Thor Hallen) and the 7A22 (designed by Val Garuts) used essentially the same circuit. Exactly who came up with the brilliant input circuit is lost to history. The 1A7A came out first, but Thor had worked as evaluation engineer for Val Garuts. Val does not remember who created the circuit, and Thor died in 2002.
|In 2023 Dollars||$3,900||$3,800||$3,900||$4,700||$5,300|
7A22 front view
left side (with cover)
7A22: 1 kHz, 130 μVp-p triangle, BW=1 MHz
7A22: 1 kHz, 130 μVp-p triangle, BW=100 kHz
7A22: 1 kHz, 130 μVp-p triangle, BW=10 kHz
7A22: 1 kHz, 130 μVp-p triangle, BW=1 kHz
15 μV p-p triangle wave displayed in variable-persistence storage mode on a 7613 for noise filtering