Thank you Nazarou, At this point my expertise regarding having the tube run with the idle current up to maxium dissapation is behond my level of understanding. It would seem to me that a unique test circuit would need to be implemented to perform the old stock energize tube procedure. However I do actually have the Mullard, Telefunkens and many other desirable industrial old stock tubes which I need to protect. Right now my filament supply uses a 12v regulator. When I look at One of my RCA's filament light up very brightly at first turn on, I know that might not be the best method for lighting the filaments. I have a Jackson 648 tube tester which has a line control, which adjusts the line voltages. The unit also has a plate control which changes the plate voltage. Can I simulate the Tube wake up procedure with this tester. I can also use a variable transformer. Thanks anyone. Yero
Follow the next idea below:
Just put a resistor in series with the heater supply,
and add a bypass switch.
Your inrush / surge worries are over as long as you can manage a standby switch and count to ten.
(1) Calculate the total expected load:
typical 12AX7s etc. draw about 150-350 mA each.
(300mA per heater at 6.3V or 150mA at 12,6V )
6.3/.3 = 21 ohms hot resistance for each tube.
Lets assume the cold resistance is only 1/10 the hot resistance.
(you can measure it with an ohmmeter: I get 3.6 ohms cold with heaters in parallel).
3.6 ohms means you're missing the other 17.4 ohms during the warmup, so thats the value of your series resistor.
You turn on the power with a 15 or 20 ohm resistor in series for one tube.
halve it for two in parallel (e.g. 10 ohms) , halve it again for 4 tubes. (5 ohms).
No more inrush on the tube heaters, causing rapid expansion and wear/tear breakage (the most common failure).
After they warm up a bit, shortout (bypass) the resistor,
and the heaters should glow up to normal.
You can put this on a 10 second relay to automate it,
powering the relay with the A.C. mains.
Now you have no worries.
Tubes get a nice slow-start, causing their heaters to last 10 to 100 times as long.
The most significant single thing you can do for tubes: slowstart.
Sorry to ask it, but you had a link to these baking tubes threads??
I fail to find it.
Thanks
It is common practice to revive CRT applying voltage to grid 2 with the cathode grounded, then a little touch to grid 1, et voilá !!! the CRT is like new
(or dead
)
Most of the time it works, I remember an old Panasonic that looked all black, then the procedure seemed just out of factory, five years ago that works as well !!!
The applied electric field is so strong that "clean" the cathode.
It would only be a matter of finding the appropriate field for other types of valves.
It might work.
Increase the filament voltage reduces the valve life, the result does not last long, only as a last resort.
(or dead
)Most of the time it works, I remember an old Panasonic that looked all black, then the procedure seemed just out of factory, five years ago that works as well !!!
The applied electric field is so strong that "clean" the cathode.
It would only be a matter of finding the appropriate field for other types of valves.
It might work.
Increase the filament voltage reduces the valve life, the result does not last long, only as a last resort.
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