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572 tubes update

Discussion in 'Amateur Radio Amplifiers' started by W8JX, May 15, 2015.

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  1. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    OK, thanks, LJ... then the tube that lights but suddenly can't pass current means the grid or plate wire or weld opened up.
     
  2. KA9JLM

    KA9JLM Ham Member QRZ Page


    I would check the tube socket before I cut it open, repair it and put it back in a vacuum.

    You can work thru a very small hole, Like a ship in a bottle.

    Just put the vacuum back after you fix the connections. JB weld works fair with re-sealing glass, If the hole is not to big.

    I made my Vacuum chamber out of a big Mason Jar. Same kind I use to catch lightning.


    Have Fun Everyone.
     
  3. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Thanks, Don. The other symptom in this issue was that the problem followed the tube when they were swapped. I also seem to remember that G3YRO was running a bit of color (more than a blush, but this is always subjective). My guess is that if you want to run them hard (in AM 150 watts carrier perhaps, or warm up the shack in the winter), one wants a bit more cooling than is stock in an SB-200.

    With repeat offenses, it may be an idea to check for airflow problems in and around the amp.
     
  4. VE7GPG

    VE7GPG XML Subscriber QRZ Page

    Same experience in my FL-2100B - just a nice glow - no red or orange at 600W
     
  5. AA9G

    AA9G Ham Member QRZ Page

    What is the purpose of placing old tubes in a vacuum before use? Are you trying to pull out gasses?
    How much vacuum (inHG) is required to exceed the internal tube vacuum and how do you even know what that figure is?
     
  6. K8ERV

    K8ERV Ham Member QRZ Page

    Sounds like a plan to me.

    TOM K8ERV Montrose Colo
     
  7. KA9JLM

    KA9JLM Ham Member QRZ Page


    You do have a valid point.

    Sometimes the vacuum will seal the tube again, So it is best to start slow.

    If the filament is already opened then forget recovery. Someone may have fired it up and burnt the filament out, Before putting the tube in a Vacuum.

    The Vacuum you can achieve depends on your atmospheric pressure.

    It may be around -1 atmosphere but don't quote me on that. I was wrong once before.


    Have Fun Everyone.
     
  8. W8JX

    W8JX Ham Member QRZ Page

    Not really. It depends on how good a pump you have...
     
  9. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Yes.

    Does it matter? You can only pull what you can pull and it's either good enough or not.
     
  10. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    And all the other seals and materials of the entire chamber.
     

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