Looking for a cheap dual pentode

[Bitrex]

I'm wondering if anyone can recommend a cheap dual pentode - not for hifi use, but experimenting with tube relaxation oscillators. The cheaper and funky-junkyer the better. Any heater voltage under 20 volts or so is fine, low plate voltage operation is a plus - maybe one of the automotive type tubes? Something used in tube type TVs? Any suggestions welcome!

 

[Wavebourn]

I've seen a lot of such compactrons (tubes for late TVs)

 

[Jeb-D.]

6BN11

There are some other compactron dual pentodes that would work, but that's the only one I know off hand.

 

[smoking-amp]

6BN11, 6J11, 8CB11, 6BV11

The 6BV11 (also 6GY6, 6HZ6, 6AS6, 6DB6, 6DT6, 9KC6, 7AK7, 6888) has dual control grids on each pentode which could be used for a gain control.

The sorta dual pentode 6LE8 family includes 6BU8, 6KF8, 6MK8, 6GS8, 6HS8

There are also a bunch of dissimilar dual pentodes (compactrons) where one unit is a power pentode:
6AL11, 6G11, 6AF10, 8BM11, 9BJ11, 6AD10, 6BF11, 6BY11, 6T10, 6Y10, 12AE10, 13V10, 18AJ10,

or where one unit is semi-remote cutoff: 8BQ11, 6AR11

or really weird ones with a pentode + gated beam discriminator: 6J10, 6Z10, 17AB10, 17X10