3B2
From TekWiki
The Tektronix Type 3B2 is a delaying timebase introduced in 1963 for 560-series scopes except the 560 and 565. It can trigger on signals up to 30MHz.
The 3B2 has a 6CW4 Nuvistor triode cathode-follower buffer amplifier at the trigger input, followed by a differential trigger amplifier made of a pair of PNP transistors, with a 2mA tunnel diode acting as the actual trigger.
The 3B2 has a 1MHz crystal oscillator and a counter made of discrete transistors. It generates output pulses that enable it to communicate with a digital unit such as the 6R1 or 6R1A.
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