AusTex64
Well-known member
- Joined
- Jun 3, 2013
- Messages
- 526
I'm working with a circuit that uses 6DJ8 family tubes in a White follower topology on the output. No output transformer. Problem is tube life is about 20 hours before emission starts to drop on the tube. Guessing that the tube is being run too close to edge of design. Am considering lowering cathode current/emission with the hope of extending tube life. Will it work?
Another question is which tube of the family might offer the best life? All are 6.3V heaters on a regulated DC supply, BTW.
Here is some data on my options:
6DJ8 - 365mA heater current, 1.8W anode dissipation per side.
https://frank.pocnet.net/sheets/191/6/6DE4.pdf
6922 - 300mA heater current, 1.5W on single side, 2W max on both side operation simultaneously. https://frank.pocnet.net/sheets/049/6/6922.pdf
7308 - 335mA heater current, 1.65W anode dissipation per side.
https://frank.pocnet.net/sheets/168/7/7308.pdf
I always thought that all these tubes were basically the same tube, like 12AX7 and 7025 are related. 7025 being a noise and vibration selected 12AX7. But all these tubes are obviously different in heater, cathode and plate construction, to offer different performance tube to tube.
Thanks!
Another question is which tube of the family might offer the best life? All are 6.3V heaters on a regulated DC supply, BTW.
Here is some data on my options:
6DJ8 - 365mA heater current, 1.8W anode dissipation per side.
https://frank.pocnet.net/sheets/191/6/6DE4.pdf
6922 - 300mA heater current, 1.5W on single side, 2W max on both side operation simultaneously. https://frank.pocnet.net/sheets/049/6/6922.pdf
7308 - 335mA heater current, 1.65W anode dissipation per side.
https://frank.pocnet.net/sheets/168/7/7308.pdf
I always thought that all these tubes were basically the same tube, like 12AX7 and 7025 are related. 7025 being a noise and vibration selected 12AX7. But all these tubes are obviously different in heater, cathode and plate construction, to offer different performance tube to tube.
Thanks!