GR-B

This is an early tube manufactured by Rodan-Okaya of Japan. It is unusual because it includes a display of the number 10. The tube looks to be a variation of the GR-1, judging by the style of the labelling on the tube. This would mean that the tube does not contain mercury, so it would have a short lifetime. There is also a version of this called the GR-542 that, judging by the label style, appears to be a version of the GR-201, which would mean that that tube did contain mercury.

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