432
The Tektronix 432 is a 25MHz dual-trace portable oscilloscope. There is also a rack-mount version, the R432. Each 432 vertical signal channel starts with the coupling switch, then a rotary cam attenuator, then a dual-JFET source-follower buffer amp, then a 155-0050-00 differential amplifier (switched to 155-0050-01 after serial number B239999).
The vertical and horizontal output amplifiers are fully discrete, using silicon bipolar transistors.
Triggering is done by a 4.7mA tunnel diode that is fed by a discrete trigger amplifier.