This 9 cm amplifier features a YD1060 valve and can generate up to 5 Watts of RF. The cavity amplifier was built by Cyril G3VVB.
All such amplifiers operate the triode in grounded grid mode. The cavity will be in fact two cavities stacked upon each other with the grid in the plane of the middle disc.
Seen side on, the aluminium cooling fins on the YD1060 triode anode are plain. The actual anode will be a copper disc that the cooling fins attach to and will be level with the top plate of the cavity. The anode connection is the tag on the left.