Has anyone out there ever used a 3B/240M (CV2214) valve / tube in an HF amplifier?

3B-240M / CV2214

3B-240M / CV2214

I came across one of these, new and boxed, amongst my collection of treasured family heirlooms…it looks like a miniature 5B/254M but isn’t.  The 3B/240M or CV2214 is a small grounded grid triode for use up to 200MHz.  It needs just 275V on its anode and about 2W cathode drive to give a comfortable 10W or so output.  Anode current will peak at 80mA and the heater needs 6.3V at 1.1A.

I only had one of these but found two more on the web, that weren’t at silly prices…it seems the usual suppliers believe the audio boys want them.  It isn’t a good idea to embark on a project with only one of anything, so now I have three, it is safe to have a play.

What I’m looking at is a 40m QRP SSB transmitter, using one of these as a final driven by something like a 5763 or similar, and the preceding stages.  I could end up using a 2E26 as I have several of those, but this is a nice short valve and so deserves a chance 😉

So, if you’re reading this and have been experimenting with these in an HF amplifier, please drop me a line via my ‘contact’ page…thanks.