This video shows the testing of 6J1 and 6AK5 vacuum tubes on a vintage Chinese GS-5A tube tester. The Chinese manufactured 6J1, which is a substitute for 6AK5 tubes, is a well made tube – in my opinion, one of the “gems” among vintage Chinese tubes.
If you are interested in GE 5654W (which is a premium substitute for 6AK5 and 6J1), please follow this link to my amazon store.