Variable-Mu Tube

variable-mu tube

[′ver·ē·ə·bəl ¦myü ′tüb] (electronics) An electron tube in which the amplification factor varies in a predetermined manner with control-grid voltage; this characteristic is achieved by making the spacing of the grid wires vary regularly along the length of the grid, so that a very large negative grid bias is required to block anode current completely. Also known as remote-cutoff tube.

Variable-Mu Tube

 

a pentode whose anode-grid characteristic has a long, gently sloping lower region and a steep upper region. As a result, the slope of its characteristic and the gain per stage using such a tube can change by a factor of several hundred. Variable-mu tubes are used in radio receivers and in wire communication receivers for automatic gain regulation.