The FW4/500 full wave rectifier is a higher power device than most full wave rectifiers at 500 Volts at 250 mA. The valve is directly heated with oxide coated ribbon filaments.
The maximum reservoir capacitor is 16 µF and the minimum effective series resistance has to be a minimum of 200 Ω to protect the cathode.
The tall pair of anodes with supports set into the pinch and a top mica pressed against the shoulder of the envelop.
The face of one anode. The ribs add rigidity to the thin nickel sheet.
The mica 'fingers' gripping the glass and the filament tension springs and ribbon filaments.
The pinch and lower mica disc. AS the mica disc does not tough the envelope the pristine nature of the 'fingers' can be seen.
The classic envelope is 49 mm in diameter, and excluding the B4 base pins, is 120 mm tall.
References: Data-sheet, 1040 & 1043. Type FW4-500 was first introduced in 1939. See also1939 adverts.
