:I bought an old Supreme tube tester so I could test vintage tubes like a 6A7 with seven pins. The Supreme tester has a 7 pin socket but the tube does not fit (the pins are spaced closer and smaller than the socket). Were there different size tubes available way back when? Nick

Hi Nick

There were two size 7 pin bases used on early radio tubes. 6A7 uses the smaller spacing. Type 59 has larger spacing. Many tube testers have a 7 pin socket that will fit either spacing.

Norm

::I bought an old Supreme tube tester so I could test vintage tubes like a 6A7 with seven pins. The Supreme tester has a 7 pin socket but the tube does not fit (the pins are spaced closer and smaller than the socket). Were there different size tubes available way back when? Nick

::I bought an old Supreme tube tester so I could test vintage tubes like a 6A7 with seven pins. The Supreme tester has a 7 pin socket but the tube does not fit (the pins are spaced closer and smaller than the socket). Were there different size tubes available way back when? Nick

Hi Nick. I have had good luck adding extra sockets to several tube testers. Often without having a schematic. The 'Precise' testers origionally had a blank spot on the front for an added socket. All had the sockets paralled. Hope this helps. Ivan Copas