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The Tektronix Type 422 is a 15 MHz portable dual-trace oscilloscope introduced in 1966. It was available with an optional battery back for operation without mains power.

Key Specifications

Bandwidth DC to 15 MHz
Risetime < 23 ns
Sweep 500 ns/div to 0.5 s/div
Input impedance 1 MΩ ±2% // 30 pF
Delay line 150 ns, internal delay line
 Input voltage Max. 300 V combined DC and peak AC
Trigger source CH1 & CH2, CH1, External
Channel isolation 100:1 at 40 KHz
Calibrator ~1 kHz ±20%, 2 V ext jack, 0.2 V internal, square wave
CRT T4220 tube, P31 phosphor, 6 kV acceleration (Post-def 4.9 kV), 8 × 10  graticule, 0.8 cm/div
Operating temperature –15 °C to +55 °C
Power AC PS, 110/115/125 or 210/230/250 VAC ±10%, 45 Hz to 440 Hz, 40 W
AC-DC PS, 92–137 or 184–274 VAC, 45 Hz to 440 Hz, 11.5–35 V DC, 30 W
Dimensions AC PS (H/W/D) 6.75/10.0/17.8 inches, AC-DC PS (H/W/D) 6.75/10.0/20.7 inches


Documents Referencing 422

Document Class Title Authors Year Links
Tekscope 1969 V1 N4 Aug 1969.pdf Article Nickel-Cadmium Battery Rev1ew 1969


Early versions use an 8056 Nuvistor tube for the front-end cathode follower. Later versions use a FET front end. The 8056 Nuvistor used in the input amplifier of the 422 can be replaced by a MPF102 JFET.

The trigger circuit in the 422 has a trigger amplifier driving a 1N3719 tunnel diode, D375, which acts as a Schmitt trigger. The trigger amplifier has a nonlinear deadband diode circuit in the negative feedback path. What results is high gain for small signals (little or no negative feedback) and low gain for large signals (strong negative feedback). Thus, the signal at the base of Q364 has a limited swing over a wide range of input amplitudes. The collector current of Q364 varies between 0 and 9 mA. Depending on the position of the trigger slope control, higher collector current in Q364 either switches D375 from the low-voltage state to the high-voltage state or from the high-voltage state to the low-voltage state. When D375 transitions from the low-voltage state to the high-voltage state, it produces a current pulse in the primary of transformer T401, which produces a current pulse in the secondary of T401. The secondary of T401 feeds another tunnel diode, D405, and the current pulse switches D405 to the high-voltage state, which starts a sweep.

The 422 uses the T4220 CRT.






Some Parts Used in the 422

Part Part Number(s) Class Description Used in
1N3714 152-0081-00 Discrete component 2.2 mA, 25 pF germanium tunnel diode 546 547 556 21A 22A 3B1 3B2 3B3 422 491 283
1N3719 152-0182-00 Discrete component 10 mA, 50 pF germanium tunnel diode 422 661 7B92 7B92A
8056 154-0417-00 Vacuum Tube (Triode) low-voltage Nuvistor triode 422 502 W 1S1 3A7 3S3 3T4 5T3 10A1
STD933 152-0181-00 Discrete component 1 mA, 5 pF germanium tunnel diode 1S2 221 422
T4220 154-0466-00 154-0466-05 CRT rectangular 3⅜ × 3⅞ flat-faced CRT 422
TD714 152-0402-00 Discrete component 2.2 mA, 25 pF tunnel diode 1401 1401A 283 R283 3B2 3B3 422 491 546 RM546 547 RM547 556 RM556 SPG11 SPG12
ZZ1000 154-370 154-0370-00 Gas Discharge Tube (Voltage regulator) 81 V voltage reference 129 3B1 3B1S 3B2 3B3 3S76 422 S-311