The 6l17 is a mystery with no data-sheets so far found. Careful looking at similar valves indicated that the 30L17 looked the same. Thus the conclusion is that the 6L17 is the parallel heater version of the series heater 30L17. The 30L17 is the frame grid version of the 30L15.
The 30L17 is a double triode with unusual connections. It was designed for cascode (series) operation in the front ends of television receivers.
Made in England and BVA.
The grid supports do not have a visible crossbar that usually define a frame grid. But internally the grid winding are made with very fine wire.
The cathode tube is rectangular and between the sections is an electrostatic screen.
The lower mica and again there is no crossbar on the outside of the grid supports.
Thanks to Edward Jeflea for donating this exhibit and confirming the analysis of probable type.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 46 mm tall.
