128

The Tektronix Type 128 is a power supply for Type P500CF cathode-follower probes. It was introduced in 1958.

It provides two voltages to the probe: regulated +120 V DC, and unregulated +6.3 V DC. Low voltage rectification is done by a selenium rectifier. Higher voltage rectification is done by a 6X4 tube. The voltage reference for the +120 V supply is produced by a 5651 tube.