The 6289 ceramic UHF triode with coaxial connections designed to be used in a resonant cavity. We can find no details on this Type.
The ML8533 is similar and this probably operates in the same spectrum area.
The top connection is one of the heater connections and the cathode the other heater contact is inside the top tube. The cylinder above the ceramic ring is the grid connection. The last connection is the anode. Clamped to the anode is the aluminium fin section.
The hexagon heads of the fin section clamp.
The small separation between the cathode and grid connections.
The thin ceramic tube envelope is 19 mm in diameter, and including the base is 67 mm tall.
Updated April 05, 2019. shape:planar construction:disc.seal.(ceramic) type:triode age:1960.1975 base: pin: