This exhibit is an Atlas 100 Watt dummy load.
Click here for the data-sheet. We also have the CV1872, a 200 Watt dummy load.
The resistance wire is wound onto a former made of mica sheets arranged around a central support. The twin wires are wound in opposite directions on alternate support notches in the mica and thus an attempt is made to minimise the winding inductance and thereby raise the operating frequency. Even with these methods the lead lengths are significant and we suspect that it was of value in the low MHz only.
The balloon envelope is 75 mm in diameter, and excluding the B4 base pins is 119 mm tall.
Updated April 05, 2021.