The E2056 experimental valve from M-OV has three wire grids and so is a pentode. The bright anode points to a low power device. We have three of these valves, s/n 19, 22 & 24.
The box has written on it that this is a straight HF pentode.
The valve is indirectly heated and testing the heater showed an orange red glow at 6.3 Volts and that took 0.2 Amps. Pin 5 has the suppressor grid connection shielded.
No other B7G valve seems to have the same pin connections. The isolation of g3 suggests that it is used as an active control element.
The three wire grids can be seen at the top. The lower right of the image shows the screen around the pin 5 connection.
The identification is written on the anode.
The lower mica and connections.
Here we have another example of the E2056.
The 5056 is also written on the anode itself.
The wire grids and the heater can be seen under the mica.
The grids and their spacing around the cathode.
The third example. The first two grids are easy to see but the third grid, an open helix, is not visible in the image..
The lettering seen here is written on the anode and not the envelope.
The plain anode cylinder.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 45 mm tall.
