This 715B has the JAN prefix that denotes a specification agreed for the Joint American Army and Navy. The prefix could also have been JAN-CRP where the CRP denotes Raytheon as the supplier/Manufacturer. The Type designation is 715B.
The 715B is a tetrode pulse modulator intended to be driven by a rectangular pulse. The peak current demands require four independent cathodes and the warm-up time should be three minutes if full current is to be drawn. The peak pulse power is 225 kW and the anode has a 60 Watt dissipation.
The 715B is a direct equivalent to the STC P535-1E and was intended for use in aircraft radar systems.
The all glass construction with the base pins held in a ceramic plate and capped with larger cylindrical ends.
The anode connects to the top cap, the grids are gold plated and have radiating fins on top - control and screen grid. The dissipation is on average only 60 Watts so the anode is made of pressed nickel sheet and not graphite.
A closer view of the electrodes. The copper grid supports clearly show the notch and peen method of fixing the wire to the rods.
The wide glass tube envelope is 64 mm in diameter, and excluding the B4A base pins is 134 mm tall.