The Type 1A5 is a differential amplifier plug-in for 500-series scopes. Bandwidth is 50MHz down to 5mV/div. The maximum differential sensitivity is 1mV/div, with a bandwidth of 40MHz. Common-mode rejection is 20,000 to 1 at low frequencies, deteriorating to 200:1 at 20MHz. Like most Tektronix differential plug-ins, it has three modes: Va-Vc, Va-Vb, and Vc-Vb. Vc is controlled by a ten-turn pot and can vary from -5V to +5V (0.5V on the 5V/div to 20V/div ranges). There is a front-panel jack for direct connection of the Type P6046 Active Differential Probe. Type 1A5 was introduced in 1967, replacing Types W and Z, and lasted until the end of the classic plugin scope line in 1974.