TVAD. Joe's mention of the description "shield" might refer to the "PQ" logo. It's a shield with the letters PQ and two stars inside. OR, he could be refering to the internal construction of the tube whether it's shielded or not shielded.
I have some 7308 PQ with the shield logo as well as JAN 7308 with no PQ logo. They are the same tube. PQ's were labeled for general consumers where JAN labels for the military.
The difference between the 6922 and 7308 is minuscule, to my ears.
I have some 7308 PQ with the shield logo as well as JAN 7308 with no PQ logo. They are the same tube. PQ's were labeled for general consumers where JAN labels for the military.
The difference between the 6922 and 7308 is minuscule, to my ears.