The FA7 is a Xenon flash tube from around 1964 with a 200 J rating and an operating voltage of 2,500 V. The trigger voltage to initiate the flash is a minimum of 3.5 kV.
The Xenon gas filling gives a colour temperature for the discharge that corresponds to noon daylight, approx 5,500 °K but the actual colour temperature for this flash tube is not quoted.
The flash duration at half peak is quoted as 290 μs and the rated life at full power is 10 million flashes. The capacitor given in the specification is 64 μF and the discharge length is 255 mm.
The mesh surrounding the centre leg of the flash tube is the trigger electrode.
Connections to the main electrodes and the trigger mesh.
The Bakelite base.
Another FA7 with less damage to the lettering.
View looking along the helix of glass. The trigger electrode is a sheet of wire mesh.
The wide glass tube envelope is 31 mm in diameter, and excluding the UX4 base pins is 80 mm tall.
References: Internet: lamptech web site.
Updated February 21, 2014. shape:wide.glass.tube construction:glass.foot type:flash.tube age:1960.1975 base:ux4 pins:4 pin: