422

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Tektronix 422
15 MHz portable dual-trace scope
Tektronix 422 front

Produced from 1965 to 1975

Manuals
Manuals – Specifications – Links – Pictures

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
Rise time < 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 temprature -15 °C to +55 °C
Line Voltage/Power AC PS 110/115/125 OR 210/230/250 VAC ±10%, 45 Hz to 440 Hz, 40W
Line Voltage/Power AC-DC PS 92-137 OR 184-274 VAC, 45 Hz to 440 Hz, 11.5-35 V DC, 30W
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

Internals

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.

Links

Pictures

External

  • R422, compartment closed

    R422, compartment closed

  • R422, compartment open

    R422, compartment open

  • Black 422, panel mount

    Black 422, panel mount

  • 422 trace is sharp

    422 trace is sharp

  • 422 in ALT

    422 in ALT

Internal

  • Tek 422 Internal LHS

    Tek 422 Internal LHS

  • Tek 422 Internal RHS

    Tek 422 Internal RHS

  • Tek 422 Internal Top

    Tek 422 Internal Top

  • Tek 422 Internal Rear

    Tek 422 Internal Rear

  • Tek 422 Internal Underside

    Tek 422 Internal Underside

  • Tek 422 Internal V-Amp

    Tek 422 Internal V-Amp

  • Tek 422 H-Amp Board

    Tek 422 H-Amp Board

  • Tek 422 Trigger Board

    Tek 422 Trigger Board

  • Tek 422 Input Board#1

    Tek 422 Input Board#1

  • Tek 422 Input Board#1

    Tek 422 Input Board#1

  • Tek 422 Indicator unit - Regulator

    Tek 422 Indicator unit - Regulator

  • Tek 422 HV Case

    Tek 422 HV Case

  • MPF102 replacing 8056

    MPF102 replacing 8056

  • Tek422 AC Power Supply Module

    Tek422 AC Power Supply Module

  • Tek 422 AC Power supply Internal

    Tek 422 AC Power supply Internal

  • Tek 422 AC Power supply Internal

    Tek 422 AC Power supply Internal

  • Tek 422 AC Power supply Internal

    Tek 422 AC Power supply Internal

  • Tek 422 AC Power supply Internal

    Tek 422 AC Power supply Internal

  • Tek 422 AC Power supply Internal

    Tek 422 AC Power supply Internal

  • Tek 422 Indicator unit, Power supply Test points

    Tek 422 Indicator unit, Power supply Test points

Schematic

  • Trigger circuit

    Trigger circuit

  • Sweep circuit

    Sweep circuit

  • Vertical amplifier circuit

    Vertical amplifier circuit

  • Input amplifier circuit

    Input amplifier circuit

  • Horizontal amplifier circuit

    Horizontal amplifier circuit

  • CRT circuit

    CRT circuit

  • ac-dc power supply

    ac-dc power supply

  • ac power supply

    ac power supply


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
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