27 March 2021

Help with unknown vacuum tube / valve

In the assortment of vacuum tubes I bought there are few items that look all the same and all without marking. What is worse is that they do not look like any of the almost 40 kinds of tubes that do have a marking!

So I ask my readers for help to give a name to these B9A/noval tubes. All nine pins are connected. There are two identical sections and filament runs happy at 6.3V. The anode/plate is probably connected to pin 9.

Is it a double triode? A double pentode?

Please suggest your answer in the comments or via email to ik1zyw at yahoo.com. Thanks!

"Side" view.
"Front" view.


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