59

The Tektronix Type 59 is a 400 kHz amplifier for 560-series scopes. It was introduced in 1961, and at $50, it was the lowest-priced plug-in in 560 series.

It does not have a calibrated input attenuator. The input takes banana plugs. The deflection sensitivity is about 1 div/volt. The input impedance is 250k ohms.