The Tungsram AR4101 dates to 1931 and is a medium-μ triode. Tungsram in their 'Symphonic' range advert suggest the AR4101 is used as a detector. This would be in a straight or TRF receiver.
The reverse of the metallised envelope carries the words Made in Hungary.
The dome carries the identification and the fact that this is a Barium Tube ie made by the Azide process.
The balloon envelope is 45 mm in diameter, and excluding the B5 base pins is 92 mm tall.
Reference: 1043. Type AR4101 was first introduced in 1931. See also1931 adverts.
