RCA 6SN7GT Brown Base 1951 | RCA 6SN7GT Black Base Grey Glass 1951 | Swedish Military Crown Stamped on Base

[robolton]

Thought I would share with the audience as I have never seen these before, just had to add them to my collection. Also having a hard time finding any reference to these tubes.

 

[robolton]

Today their cousins showed up > RCA 6SN7GT Black Base Grey Glass 1951 | Swedish Military Crown Stamped on Base

 

[Lowrider75]

Today their cousins showed up > RCA 6SN7GT Black Base Grey Glass 1951 | Swedish Military Crown Stamped on Base

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The RCA grey glass are stamped Made in USA. These are possibly for export to Sweden.

Somewhat similarly, Brimar sold ECC83's in the UK but marked many of them 12AX7 for the US.