6E5P 6E5P / 6Э5П Tetrode Vacuum Tube

The 6E5P (Russian: 6Э5П) is a Soviet-era frame-grid beam tetrode developed by Reflektor (Saratov) in the late 1950s for wideband HF voltage and power amplification. The frame-grid construction places its control-grid wires within micrometres of the cathode, yielding a remarkably high transconductance of about 30 mA/V and a plate dissipation of 8 W in a noval glass envelope only ~22 mm in diameter. Although designed for radar and pulse work, it has earned a strong audio reputation when triode-strapped (g2 tied to the plate): in that mode the tube measures roughly mu=32 and rp=900-1000 ohms (per Ale Moglia's uTracer extraction at Bartola Valves), making it a fast, low-impedance driver of choice for SET 300B, 2A3, GM70, and KT88-triode output stages. Coleman's Shunt Cascode topology is the textbook application. In any audio role the tube benefits from a DC-regulated heater and a 20-30 minute warm-up before stabilisation. Production was heavy from 1960 through the 1990s, mostly Reflektor with some Foton, and NOS supply remains moderate. Sources cross-checked: Reflektor Saratov original datasheet, BSS Spravochnik, frank.pocnet.net, Bartola Valves SPICE extraction, JacMusic curve measurements, and Coleman Audio application notes.