The RFP15 is a pentode transmitting valve capable of delivering 15 Watts in the HF region.
362 describe the RFP15 as having been specially for the Radio Amateur (colloquially known as 'Hams').
The makers label. On the base the output power is given as 15 Watts and the input drive as 1 Watt.
The valve is double sided with an anode either side of the central electrodes. The stout wires passing between the three grids and the anodes are supports for filament tension springs. The data gives the valve as having a cathode but the actual valve has an oxide coated filament.
The three wire wound grids all pass flat across the six filament strands.
Four of the filament strands connect to a support that fixes in the pinch but is not connected to the base. One pair of filament supports are connected together at the top and do not have a base connection. The single filament support does connect to a base pin and is the centre point of the filament. This must be the connection referred to as the cathode.
The three grids and filament strands.
This shows the distances between the grids and the pitch of the windings.
The unusual anode is made of nickel tape spot welded and pulled apart.
The classic envelope is 60 mm in diameter, and excluding the B5 base pins is 154 mm tall.
Reference: 1043. Type RFP15 was first introduced in 1936.