The 845 was upgraded to this rugged form and issued the Type designation of 845W.
The 845 is an audio power triode with an anode dissipation of 75 Watts and operates with up to 1,250 Volts on the anode. The thoriated tungsten filament is powered at 10 Volts and 3.25 Amp.
The United Electronics Company logo and Made in USA.
The glass tube at the level of the pinch has no electrical connections and is probably a form of gettering. High voltage valves and transmitting valves would have been pumped to a harder vacuum than consumer types to remove the need for the getter that could be a source of insulation breakdown.
The electrode supports pass to a collar around the pinch stem. Note the twisted wire of the anode connection.
The upper support is a substantial piece of ceramic. One extra present on the W variant is the glass rod from the dome that passes into a ring at the top of the main support rods. The filament is held under tension by the two helical springs.
Here the thickness of the graphite anode can be seen. The control grid is visible as is one inverted filament.
An alternative view with a clear view of part of the filament.
The wide glass tube envelope is 57 mm in diameter, and excluding the special base pins, is 185 mm tall.
References: Data-sheet & 4061. Type 845W was first introduced in 1952. See also1952 adverts.
