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2HF

 
See also:
The Bi-grid Valve
    
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The 2HF is one of the small number of types of Loewe multivalves. In this case the valves and passive components are for the purpose of providing two stages of RF amplification. The valves are used as space-charge devices and not as tetrodes.
The two electrode assemblies are mounted either side of the glass encapsulated resistors.
The six wires emerging from the lower flare of the pinch and are attached to the small brass pins. The three flat spikes are the the bayonet fixing lugs.
The individual valves are built on supports held in a glass rod. The rods emerging from the pinch then are welded to the valve supports and also to the central passive components.
A close-up of one of the bi-grid valves. The construction matches that of similar single bi-grid valves.
One of the pair still has an intact filament. The picture shows the way the helical wound grids are fixed to the support rods. The filament is held by clamping into the support rod. One weakness of the multi valve design was that failure of one filament ended the life of the whole device. Loewe are reported to have offer a repair service. Clearly an expensive valve to produce.
The Loewe Valve logo and the type designation. Also the anode tab.
A resistor sealed in glass.
The individual valve assembly is a work of art. Note also the evacuation seal on the tube housing the resistor.
The polished nickel anode and molybdenum grid wires.
Another clear view of the resistor in glass and the sheet anode rolled into a cylinder.
The Bakelite base. The pointed brass pins press into the springs set into the base. The connections to the base contacts can be seen around the edge of the base.
The underside of the base showing the spring contacts.
The pin connections and internal wiring.
The wide glass tube envelope is 46 mm in diameter, and excluding the base pins is 147 mm tall.
Reference: Datasheet.

 

Pin Connections
1
2
3
4
5
6
g2(1)
f-
a(2)
a(1)
f+
g1

 

Absolute Maximum Operating Conditions
The Bi-Grid Valve
Vh
Ah
4.0
-
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated May 27, 2014.
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