Pentagrid Converter
This tube tests NOS but has a Rusty base.
The 1A7GT Vacuum tube is a glass octal type used in
superhetrodyne circuits having battery power supplies. It
requires an octal socket and may be mounted in any
position.
Be careful when purchasing 1A7 tubes. Some tube web sites
will tell you that all 1A7 tubes are interchangeable.
This is not exactly true. The 1A7G type has a narrower
base than the 1A7GT. This allows the 1A7G to sink further
into the socket to make contact. A 1A7GT will not always
work because of its wider base and its inability to
sink far enough into the socket to make contact.
General Electric, Zenith, Philco and a few other
companies manufactured them, but they were not produced
for very long. Hence they are becoming one of the rare
tubes and the reason for the higher price compared with
the 1A7GT.
Electrical Data:
Filament Voltage ........................... 1.4 DC V
Filament Current ............................. 0.05 A
Substitutes ................................... 1B7,
1C7, 1D7, (Possibly 1A7GT).