The 13E1 is a beam tetrode designed for DC control applications. The ratings are absolute maxima and based on producing stabilised HT rails, when operating as a series pass valve. The CV6045 is identical as is the 7972, this example has no markings so could have been originally labeled as any the the identical Type designations. The internal construction is slightly different to our other examples. On the right of the main image can be seen the lower part of a heater loop and it is possible that several loops are present across the cathode box.
Inside the anode can be seen two separate cathode and grid structures, both connected in parallel within the envelope. Series pass service is very demanding for a valve and so generous cathode emission is important.
Looking at the side of the anode shows the size of the cooling fins.
The bottom of the anode showing the two grids and the thick wires that form the beam plate. The control grid is gold plated or gold wire.
The top of the anode. Extensive grid cooling fins are attached to the control grid copper support rods.
The wide glass tube envelope is 64 mm in diameter and, excluding the B7A base pins, is 124 mm tall.
Reference: Data-sheet. Type 13E1 was first introduced in 1955.