Sensibly equivalent¶ to:
The Cossor answer to the original 1927 screened grid valve from M-OV, the S625, was the SG210, another double ended valve. The single ended replacement for the SG210 was the SG220. Cossor oxide coated filament of the period were not very successful but in 1929 the New Process 'Kalenised' filament was introduced across the range. The SG220 became the 220SG.
The BVA logo and filament rating on the paper label.
The balloon envelope is 45 mm in diameter, and excluding the B4 base pins is 107 mm tall.
References: Datasheet & 1043. Type SG220 was first introduced in 1927.
Absolute Maximum Operating Conditions¶
Thanks to Andy Cowley for supplying the above PDF datasheet.
Updated October 28, 2014.