The Tektronix Type E is a low-level differential amplifier plug-in for 500-series scopes. The sensitivity ranges from 50 microvolts/div to 10 millivolts/div. The input is balanced and uses an XLR audio connector. It is an AC-coupled amplifier. It has front panel knobs for selecting the low-frequency and high-frequency cutoff. It achieves a 50,000 to 1 common mode rejection ratio. Maximum bandwidth is 60kHz. It has seven tubes on a shock-mounted subchassis.
The Type 53E/54E was introduced in 1955. Along with Types G and K, it was the first plugin offered after, not during, the original 531/535 introduction in 1954. The nomenclature was revised after just a few months, to 53/54E. In 1959, when the 5xxA mainframes came out, all plugins dropped the "53/54". Type E was dropped after 1968.