The M-OV S625 was the first screened grid valve and was released in 1927. These are rare valves and to keep sets working Peter Kyne designed the S605 as a replacement in 2002. The above article describes his work.
The basic operating details are printed on the paper labels.
A comparison of the S605 with the original S625 for Ia/Va. The absence of the kink in the modern valve suggests the presence of a suppressor electrode to eliminate secondary emission electrons.
This comparison is for Ia/Vg and shows a good match to the original.
This exhibit was presented to Gerry Wells of the Dulwich museum.
The end of the box with printed label.
The Peter Kyne dated this valve to January 14, 2002.
Original M-OV base caps. This shows the brass insert that the pins screw into.
Original M-OV base caps. This is the anode, g2 end.
The wide glass tube envelope is 29 mm in diameter and, excluding the base pins, is 96 mm tall.
Reference: Peter Kyne. Type S605 was first introduced in 2012.
