[Phlogiston]

See this auction on Pay-Bay:

https://www.ebay.com/itm/Pair-GE-6J5-Met...%3A2334524

He states the 6J5tubes test at  2300 with a spec of 2600, which is the value for a gt. The RCA manual says that his tubes would test new at 3000. This would lower the value from 86% of spec to 76% of spec. He is probably testing to the single, Hickok test value.

This would take those tubes from "strong" to meh...