The 4304CA is a VHF transmitting triode on a UX4 base. Its relatives are the VT62, 834 and the M-OV DET12.
As a Class C RF amplifier a single valve could deliver some 40 plus Watts.
The pressed anode is a finned cylinder with three side heat radiating fins. It is connected to one top cap. The other top cap connects to the helical grid. The heater and cathode connect to the base. This arrangement keeps the electrode connections away from one another.
We have yet to discover what the CA variant indicates in terms of ratings and/or performance.
The STC logo etc. is well printed on the glass and is not discoloured through use - suggesting an unused valve.
The anode and grid are supported only at the top. The helical grid attached to two vertical supports and a stout wire to the top connection in the glass.
A closer view.
The filament looks to be a thoriated tungsten double helix. A central rod up from the pinch holds the loop at the top. On test the filament glows bright orange - thoriated tungsten.
here the top of the filament support can be seen with the filament doubling back on itself.
A closer view.
At the pinch end the filament wire ends are wrapped round the lower supports.
Microscope image of the top of the central support for the filament showing the bend to form the return helix. The grid wires can be seen to be held in deep notches on the side supports.
The balloon envelope is 65 mm in diameter and, excluding the UX4 base pins, is 145 mm tall.
References: Data-sheet & 4061. Type 4304CA was first introduced in 1942. See also1942 adverts.
