This is an Osram Type R probably made during WWI for the UK Army. The envelope carries the words Made in England. The copper base shell indicates an early production valve.

The original box carries the words Valve WT for Wireless Telegraphy Valve a typical UK military type of description. The serial number 10775 is also on the box.

Thanks to Joe Gruber for sending the images.

The balloon envelope is 53 mm in diameter, and excluding the B4 base pins, is 88 mm tall.

References: ¹⁰⁰⁵, ¹⁰⁰³ & ¹⁰⁰⁴. Type R Type was first introduced in 1916. See also 1916 adverts.

Pin Connections

B4

1

2

3

4

a

g1

f

f