This is a Sylvania developmental power pentode in a glass envelope with an eight-pin loctal base. This is a spare tube for Bus Driver Flip-Flop Storage Rack S/N 6.
Date
1925 ca.
Manufacturer
Sylvania
Place Manufactured
U. S.
Identifying Numbers
Model number
SR1407
Printed in silver on top of the glass envelope.
Other number
AD59744
Stamped in green ink near the bottom of the glass envelope.
Other number
IORDC 34 V8-1
Handwritten vertically in silver ink on the glass envelope.