These Type II Ei KT90 power tubes are from one of the last remaining large lots of these hard to find power tubes. Flashing and pins show no signs of use. Grab a set while supplies last!These tubes have welded gray plates and dual O getters. They were made by Ei in the early 1990s in the former Yugoslavia. There is no label on the glass. The Type II KT90 tubes have visible spot welds where extra reinforcement was added to the plate structure to allow for greater dissipation than the earlier Type I KT90 tubes. Type II KT90s can be used as substitutes for 6550 / KT88 power tubes in most applications. These tubes have been burned in, tested at typical operating voltages on a laboratory grade Amplitrex AT1000, and precisely matched for both current draw (mA) and transconductance (Gm) at typical operating conditions (plate: 500V, screen: 300V, grid bias: -30.5V). After burn in and testing, each power tube set is also run on a custom, fully variable test fixture that can match the operating conditions of your amplifier. Price includes testing and matching.
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