EF14 and 5840 Burn-In Procedure

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Buttercup

Well-known member
Joined
Jun 8, 2004
Messages
122
Location
Devon, England.
Hi

I have Googled 'til I am blue in the face but I can find nothing useful on how to burn-in tubes.

Has anybody got a brief description and maybe I could use the voltages available from my Taylor 45D tube tester or build somnething from scratch.

Huge thanks!!

Giles
 
1. put in gear
2. turn on gear
3. leave on for at least a week
;D

Seriously, that's the way I do it. Running tubes on filament alone without B+ isn't good for the cathode, so it should be in a circuit with all the juice.

The noise floor on a 6205 (5840 sub) changed substantially in that week. I've found burn-in especially useful for NOS tubes that have been sitting in a box for, say, 60 years.

-paul
 
There's an industrial description in the Radio Designers Handbook 4th ed; there's a PDF out there, and probably still a reissue hardcopy.  The advice above is the practical answer. 
 
Brilliant!!

Thank you so much!

I have a DIY U47 clone which has taken an age to get right and I am nearly there with it.

Normally the mic uses an EF14 but I got a few 5840's and popped one in there just to see
what it was like.

The circuit is Oliver's underheated version so I guess I will need to ramp up the heater to 6.3 ( or slighty more? )
just for the benefit of the burn-in..........

Will post back in a few days when I have tried this......
 
Buttercup said:
The circuit is Oliver's underheated version so I guess I will need to ramp up the heater to 6.3 ( or slighty more? )
just for the benefit of the burn-in.........

Yep. I can't remember how well the 5840's take underheating.
 
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