434

The 434 is an analog CRT storage scope with two independent storage areas on the screen. It has a bandwith 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 20ns/div. An option for a tube with higher sensitivity at high writing speeds was available (OPT. 01).

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 12.5mA and Vgs of -0.26V. The input amplifier has unity gain, high input impedance, and an output impedance of about 120 ohms. The input amplifier drives a Tek-made differential amplifier chip, part number 155-0050-01.