1401
It covers the frequency range from 1MHz to 500MHz. It uses an external oscilloscope, typically a 323 or 324, as a display. The 1401A can be operated on batteries or 12V or wall power.
See TekScope January 1972 pages 14-15 for some servicing notes that Tek wrote after the manual was published.
There is one tunnel diode found in the external trigger circuit. It is a 152-0402-00, a 2mA, 25pF tunnel diode in a DO-17 package. It's only necessary if you use the external trigger input.
The input attenuator is a fairly custom part due to the IF gain pot that is concentric with the RF atten control. Dissassembly of the attenuator is easy after removing it from the 1401A. Note that the IF gain pot is removed via two allen setscrews. To bench test the attenuator with DC, use a 50 ohm terminator