The Tektronix 121 is a wideband preamplifier intended for 511 scopes. The voltage gain is 100, input impedance is 1 MΩ in parallel with 25 pF. The frequency response is 5 Hz to 12 MHz. It has an unbalanced signal path with switchable compensated attenuators before and after the first gain stage, a 6CB6 common-cathode amplifier. The 1121 can be considered the successor to the 121.