7308 tube code question

Good question: I only have two out right now (just received them back from a friend) and they are etched VR5, *5D (also 518 on one and 535 on the other, towards the top). The white printing is: USN-CEP 7308, Made in U.S.A., Amperex and (65-35 on one and 65-14 on the other. There may be a faint delta on the bottom (between the pins), but it may also just be a natural variation in the glass (I cannot see it clearly enough). There are no remains of a large triangle on these and as the rest of the print is in good shape I doubt that there ever was. Hopefully Kevin can further ID these. The most important thing however is how they sound.

These tubes sound awesome. I have a Sonic Frontiers Line 3SE with 10 NOS Valvo 6922. I replaced all 10 Valvos with the Amperex 7308s, and what a difference, especially in the deep bass and a more fleshed out natural midrange. The soundstage is huge with these tubes. I generally experience a subtle change when tube rolling, but this change was dramatic. Some tell me that changing all 10 tubes in my pre-amp with 7308 is overkill (instead of changing just the first two positions), but what the heck, you only live once.

USN-CEP - That is the older Navy code for Amperex Electronic Products. "C" is for Commercial. The remaining letter or letters identify a company:

CG = General Electric
CW = Western Electric
CRC = RCA (Radio Corporation)
CRP = Raytheon (Raytheon Production Corp)
CTL = Tung-Sol

The 65-35 on Dekay's tube is the date code i.e. manufactured on the 35th week of 1965. The delta symbol on my tubes are above the Amperex name and in the same colour ink as the rest of the lettering.

In the case of the delta being in paint on the tube, that doesnt' signify holland manufacture. the * does mean US made, sorry I didnt' notice that in the orig. post. Tube codes such as * and delta are always etched on the amperex, near the bottom of the tube.

-Ed

All JAN tubes, were made in the USA. That was a big reason Phillips moved a factory, to America. The USN-CEP, indicates that is was JAN, made specifically for the US Navy specification. The etched codes, indicates origin, construction, model, and authorization(acceptance)no.
They should be extremely suitable for phono sections, as this was a selected 6922, based on noise, section matching, failure rate, and on spec. longevity, to name a few.

The VR is the Philips/Mullard/Valvo code for a E188CC or a 7308 tube. The 5 after the VR denotes the fifth variation of that tube. The "*" is for Hicksville, NY, whereas the delta A would be Heerlen, Holland. The '5' after that would probably be 1965, as this tube wasn't made in the 50s and I don't think Hicksville was making them in '75, but this is a close one. If it has white labeling and given the fact that it's a CEP marked tube, I'm 95% sure it's 1965. And finally, the B is for February.

So we have US made Amperex 7308s, which are fifth versions and are consistent with a Feb. '65 manufacture date.

Simple, no?

Now whether the tubes test strong, are well matched across the triodes and are not mircophonic, I can't say. Plug 'em in and see.

Take care, Chris