Telling Matsushita 12AX7s from BEL

[Jeff West]

Someone wrote me asking about how to tell the difference in photos, if you don't have access to any codes, etc.

It's true that some '70s era Matsushitas closely resemble Bharat-made versions from the same time frame, with similar getter rings, top seams, grid rods, etc., and both can have the well-known "round holes through to inside of the plate" ruling out other contenders but not nec discriminating between Japan vs. India. Also, both of these widely carried other brandings, including some of the same ones.

There are some characteristic "feel" details that can help, like the slight cant of the halo often found on BELs, etc., also a few other things if you can really see everything "in hand". But here's a more concrete tip that might help, if you've got "holes thru" but you can't see all the other details:

As you face the plates head on, i.e., POV perpendicular to the broad area of the plate, and check the mica edge, with a known Matsushita you will likely find that you've got one of the standard mica points centered exactly in the middle of the plate and pointing right at you. With a BEL, you won't, the points are not centered in the midline of the plate, in fact there's a little extra concavity there, with points on either side (also found similarly on some other shortplates like Heerlens). Can often see this in photos.

If anyone finds exceptions, please post!

Jeff

[Jeff West]

I've got a few late '50s longplate Matsushita 12AX7s, D getter arrangement, these have inked date codes on the bottom between the pins, e.g., "MF" (= 6/59, among other things), anyone have any '50s versions, might be interesting to compare details. I like the sounds of the ones I've tried.

They also have the mica points "in the middle" like the latter ones.

[Brian Wallace]

Jeff,

Can you post some pictures of these tubes?

[Jeff West]

Hey Brian- I'll try to do that asap.

Jeff