K391A Reflex Klystron Tube Made by English Electric Valve Company Qty 1 Pc

The *K391A* is a *reflex klystron tube* designed for microwave frequencies above 3 GHz, used mainly as an oscillator at SHF/EHF ranges. It is manufactured by the English Electric Valve Company (EEV) and is also known by the equivalent designation *CV6142*

Key Details about K391A Reflex Klystron

– *Type:* Reflex Klystron
– *Frequency Range:* Super High Frequency (SHF) / Extremely High Frequency (EHF) above 3 GHz
– *Manufacturer:* English Electric Valve Company Ltd. (EEV), Chelmsford
– *Base:* Wires only (no standard socket base)
– *Equivalent Type:* CV6142

Reflex Klystron Basics

– A reflex klystron works by reflecting an electron beam back through the same cavity using a repeller electrode, enabling it to function as a microwave oscillator rather than a high-power amplifier.
– These tubes were historically used for high-frequency oscillators in radar, microwave communication, and test equipment, but are now largely outdated compared to modern solid-state devices.
– The electron beam interacts within a resonant cavity to generate microwaves, with the tuning controlled by varying the repeller voltage.

Typical Operating Data for K391A:

– *Heater Voltage:* Around 6.3 V
– *Operating Frequency:* Around 3+ GHz range typical for SHF oscillators
– *Application:* Stable, reliable microwave source mainly for laboratory or communication systems requiring discrete microwave oscillators.

Summary

The K391A reflex klystron is a vacuum tube oscillator device from the 1960s-70s era, producing microwaves above 3 GHz. It is manufactured by EEV and identified by CV6142 as a direct equivalent. It was primarily used in microwave communication, radar, and early high-frequency test equipment. It is wire-based with no standard socket and operates on typical heater voltages for tubes of its type.