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Is this the tube? If so that is where the confusion lies. It is considered an octal (8 pin) tube because it fits in an 8 pin socket. It does have only 6 pins though and only 2 of those are actually used.
Yep that's my tube, except mine is a Raytheon. Looks to be band new but no way to test it. I also found some on ebay over in the UK. Sure whish I could find someone that needed one.
I was also hoping that someone that had a tube tester could look in their manual and tell me if they can test such a thing. Then I would know what tube tester could be purchased. I also have some big 4 pin tubes with no name on them I'm wondering if there is a web site that expalins how to id tubes.
KT-88 my Hickock 752 will test the OD3, but really it is of little interest as it is not used in any audio gear. Very hard to id tubes, but usually they had paint on them at one time and it simply wore off. Breathe onto the tube, often your breath will show the hidden markings. I have used this tecnique and it has really been, ahem, revealing. Oh, and having Jack Daniels on your breath does not help; it just makes it more fun.
There a few amps that use a 0D3, and even though an 0D3 and a 0D3W look very different they are substitutes. The W just has that protective shock absorber shield around it. It can be tested with the same settings as the non W.
It is very difficult (impossible?) to identify a tube that has no markings. There were 10's of thousands of different tubes made so going just on looks is pretty much impossible.
Are there any marks at all?
The 0D3W is fairly common and doesn't demand a very high price so purchasing a tester just for it would probably lose you some money unles you have a lot of them.
Some tubes have marks but most of what is in question has nothing. These look to be of the pre amp type.
I have many large tubes thought that I can read the numbers but am not able to test on my tester. But for now I will wait until I decide if I'm going to pursue the tube quest further. I orginally bought this mess of tubes becuase of a couple that I wanted. They came very cheap. Some of these are really cool looking. To bad I can't find a use for them.