Amperex PQ 6922 vs Amperex PQ 7308

So, Ed, explain the difference between the "shield" and the "PQ". I've seen PQ tubes, but I don't know what to look for with the "shield" imprinted tubes.

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.

Dogpile, if you read Ed_sawyer's post above my last post he writes about a third 7308 tube with a shield and no PQ. I am familiar with the PQ label in the heart shaped shield. I'm intrigued by the 7308 with shield and no PQ.

IMNSHO PQ=shield, it's the graphic that is on the tube. Sorry if I wasnt' clear. I have only had PQ with shield logo, not any that are either/or.

generally 7308s are quieter and better matched. they are selected 6922s, essentially.

the consumer versions pre-date the military versions in general. Age is by color of printing to a degree. white, orange, green for printing colors, oldest to newest. usually they have date codes on them too.

as with most tubes earlier=better.

-Ed

Thanks, Ed. That was my thinking, too. Therefore, I am assuming when Joe's Tube Lore is talking about Amperex 7308 with shield, he is discussing PQ tubes whether or not he specifically mentions PQ.

Ed, if 7308 are selected 6922, then what was does the PQ designation on 6922 tubes signify?