odd tubes....

[Jonas]

I have a couple odd tubes (at least to me) curious if anyone has any experience with these?

12BH7A - Twin Triode
EF89 (6DA6) - High Slope Vari-mu RF Pentode
12HL7 - Sharp Cut-off Pentode
12B4A - Low-mu Triode

[sluckey]

The old radar system I worked on for 30+ years had plenty of 12BH7s. They were used almost exclusively for video and/or trigger cathode follower line drivers.

[kagliostro]

If you do a search here on the site you can find some thread discussing about 12BH7 tubes

Franco

[Jonas]

Thanks! I looked at the 12BH7A pinout and also did a quick search on line. I found a few references comparing it to the 12AT7. When I get a chance I will do some tube swapping on an amp I have here.

[sluckey]

12BH7 is closer to a 12AU7 than a 12AT7.

12BH7 gain is 16.5.
12AU7 gain is 19.5.
12AT7 gain is 60.

[kagliostro]

About EF89 seems in some way it is usable

https://www.youtube.com/watch?v=DWu5zhL5VmA








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Also 12B4A seems usable

https://it.aliexpress.com/i/1005004636971693.html?gatewayAdapt=glo2ita



Franco

[scstill]

The old radar system I worked on for 30+ years had plenty of 12BH7s. They were used almost exclusively for video and/or trigger cathode follower line drivers.

I also worked in Radar Systems at Hughes Aircraft in Fullerton, CA until early 90's

[Jonas]

thanks sluckey i see that now on the TDS

thanks for the schematic - I will keep them around for future projects

[HotBluePlates]

The old radar system I worked on for 30+ years had plenty of 12BH7s. They were used almost exclusively for video and/or trigger cathode follower line drivers.

The McIntosh MC-30 used the 12BH7 as a push-pull driver tube.