I got a big bag of 0B2 tubes of questionable provenance for about $0.80 each, and lucky me, only 2 were dead. Three of them are labled IEC Mullard, "MADE NI ENGLAND". They are unlike any 0B2 tubes that I had ever seen, though my experience is very limited. Instead of the usual cylindrical innards, there is a backwards "S" shaped plate(?). The regulated voltage is spot on at 108V, and they light up very brightly even with only 6mA running through them. I did a pretty extensive search on the web and didn't see anything like them. Anyone seen them before?
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wow
It's amazing，I saw this type of 0b2 for the first time，Its cathode is so small，It doesn't feel like it can pass a lot of current，ordinary 0B2 Ia=5~30mA
It's amazing，I saw this type of 0b2 for the first time，Its cathode is so small，It doesn't feel like it can pass a lot of current，ordinary 0B2 Ia=5~30mAHere too. Never saw them before. Nice!
It seems to me that in these tubes the cathode is being used on both sides (the U-shaped anode 'sees' both sides of the cathode). That and the S-shape probably make the size of the 'active' surface of the cathode just about the same as the usual cylindrical cathode of which, as far as I know, only the inside surface is 'active'.
Here are two more: Studio Six Amplifier • A pair of Mullard OB2 Gas Regulators light up the...
It seems to me that in these tubes the cathode is being used on both sides (the U-shaped anode 'sees' both sides of the cathode). That and the S-shape probably make the size of the 'active' surface of the cathode just about the same as the usual cylindrical cathode of which, as far as I know, only the inside surface is 'active'.
Here are two more: Studio Six Amplifier • A pair of Mullard OB2 Gas Regulators light up the...
How did I miss that! I ran the search again, and yep, it's right there, middle of the first page.
OK, the S-shapes structure is the cathode, got it. So the cylinders on other gas regulators are cathodes. I assumed the other way around because of the schematic symbol. I'm slowly learning.