Type M plug-in unit

This is a four channel preamplifier for the 545A and similar series of oscilloscopes.

It employs both valves and transistors. A classic feature of the Tektronix design from this era was the use of ceramic tag strips for component mounting. Silver bearing solder had to be used here and many Tektronix oscilloscopes of the era contained a small reel of this for servicing purposes.

This one is in good working order.