The SP16 Blue is a triode designated for RCC (Resistance Capacity Coupled) circuits. It has almost identical ratings to the SP-18B that was released in 1926.
The BVA logo can be seen etched into the glass. The flattened anode is a feature of the Short Path construction.
The anode seen almost face view.
An attempt to bring out the faint etched lettering. The glass has the Cosmos name the Metrovick logo the words Short Path and the Type designation.
The electrode structure. The grid is held at the back only. The filament supports can be seen passing inside the base of the grid. The anode is bright metal probably nickel.
The anode is spot welded together and further welded to the single support. Both grid and anode supports are of substantial gauge and firmly fixed into the pinch.
The BVA logo.
The balloon envelope is 43 mm in diameter, and excluding the B4 base pins is 95 mm tall.
Reference: 1043. Type SP-16 Blue was first introduced in 1928. See also1928 adverts.
