The Pen220A from Mazda is a battery output pentode.The anode load impedance is given as 6,000 Ohms and it would generate 1.1 Watts of audio at 7% distortion.The literature gives 1933 as the date of introduction, however, the Mazda advert places the introduction at April 1932.![](../pics/aaa0780a.jpg)
The wide spaced wire grid structure can be seen from the top of the dome as the anode cavity has an open top. The filament is a double inverted V.The balloon envelope is 45 mm in diameter and, excluding the B5 base pins, is 96 mm tall.References: Data-sheet, 1040, 3002 & 1043. Type Pen220A was first introduced in 1931. See also 1931 adverts. |