The 3X2500A3 or 8161 is a 2500 watt triode with a mu of 20 and a maximum frequency for full output of 75 MHz. Forced air is required. The first example is a newer version than the third example and has the more efficient anode construction. As shown in the second example, some tubes of this type were equipped with a special industrial filament connection.
Length = 8.60" Diameter = 4.16"
Max voltage = 6000
Max current = 2.5 amps
Fil voltage = 7.5
Fil current = 49 to 54 amps