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In Reply to: RE: No! posted by Paul Joppa on September 29, 2009 at 15:00:24
The J/J 2A3-40 is essentially a 300B, but with a 2.5V, 2.5A filament.So, in a fashion, this may be equivalent to using a 300B in a 2A3-configured Paramount, without having to re-wire anything.
As usual, YMMV, etc, and all of the usual caveats apply.
As Paul stated in the previous post, a 300B (except for filament voltages) will behave like a 2A3 in a 2A3 circuit, so other than for technical curiosity, there is probably no real point in proceeding with this experiment.
/ed B in NH
real radios glow in the dark
Edits: 09/30/09 09/30/09Follow Ups:
Not looking to see how it would sound. I ordered a pair of 300B that took a beating and each has a rattle. I am planning on converting the Paramounts back to 300B in a week and half when Grainger is here. I just wanted to make sure the 300Bs were functional in case I needed to order a new set before he gets here. Just want to have a working pair of Shuguang on hand since he is driving a good ways.
Tubes with a "rattle" are most likely in damaged condition.
If you have access to an emissions type tube tester, it can at least tell you if the tube is dead, shorted, or possibly still usable. Even better is a transconductance tester, which will show you the tube's real state of health (or lack thereof).
If you can't get access to a tester, try measuring the resistance of the filament between pins 1 and 4 (the two "fat" pins). This should be a low resistance value, a matter of an ohm or two, with a cold filament.
An "Open" reading means that the filament is broken.
(Look for little bits of filament wire rolling around inside of the tube's envelope).
Also check for any resistance between 1+4 and pin 2, and to pin 3, and between 2 and 3; these should all read as open. (or as infinity).
HTH
/ed B
real radios glow in the dark
Everything checked out to specifications with the meter. Nothing left to do but convert the amp and plug them in. As long as they don't damage anything, I have the original EH 300B that came with the Paramounts to use as well.
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