Hi Dana, The VR150 is a gas discharge voltage regulator tube and normally glows blue in operation. It's probably working correctly in your set and won't need replacing. The 0D3 is the same tube with a different number. It regulates the voltage across it at 150 volts (similar use as a zener diode but needs a higher striking voltage, above 180 volts). Check that the voltage across it is close to 150 volts and if so it's OK. Don Black.
: I am working on a Hallicrafters S76. The VR150 tube glows somewhat purple so I assume it contains gas. I have been unable to find a Riders schematic that would tell me the civilian number for the VR150 tube so I can replace it. Any ideas? Thanks in advance.