Special Features:

The tester mentioned in 3 (above) is a manufacturing expedient.

Properties:

A grouping of two or more separate electron tubes which have been matched together for a given characteristic such as transconductance. The matched values must be equal or within a specified tolerance. Includes only those tubes designed and specifically tested to provide a desired function. Excludes transistors, semiconductor devices and electron tubes which may be of an identical type but do not meet the above requirements.