434

The Tektronix 434 is an analog CRT storage scope with two independent storage areas on the screen.

Manuals – Specifications – Links – Pictures

It has a bandwidth of 24 MHz and uses a tunnel diode in its trigger circuit. The storage is done in the CRT itself, by trapping charge on a special fine grid of isolated pads behind the phosphor where the electron beam is then blocked or released.

There is a chopped two channel system and the fastest sweep time is 20 ns/div. An option for a tube with higher sensitivity at high writing speeds was available (OPT. 01).

Key Specifications

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Internals

The signal passes through rotary cam-operated input attenuators, then passes through an input amplifier that is on a separate small board. The input amplifier contains a JFET source-follower buffer that uses a 2N5911A (Tektronix part number 151-1032-00) biased with a drain current of 12.5 mA and V_gs of –0.26 V. The input amplifier has unity gain, high input impedance, and an output impedance of about 120 Ω. The input amplifier drives a Tek-made differential amplifier chip, part number 155-0050-01.

The original instrument design utilized an all-discrete switching power supply, making this an incredibly light portable scope. Unfortunately, this power supply was extremely difficult to troubleshoot when it went belly-up. At serial number B500000 and later, the design of the supply was simplified to use the same basic circuitry as found in the 7704A using a Tek-manufactured controller chip.

Repair Issues

See → Repairs page.

Links

• Ken Matheson, Servicing the 432/434 Oscilloscopes. In Tekscope Vol. 4 No. 5, 1972
• Handle Replacement Modification Kit

Pictures

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  side connections

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Components

CRTs used in the 434

Page	Part nos	Description	Designers	Used in
T4340	154-0666-10 • 154-0666-12	storage CRT		434

Custom ICs used in the 434