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Reformatting NOS Russian tetrode.

Discussion in 'Amateur Radio Amplifiers' started by SP4IT, Dec 31, 2021.

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  1. SP4IT

    SP4IT Ham Member QRZ Page

    Sergei, I'm trying the high voltage method now. The article says to not do more than 5 minutes. Is this correct? Did you process your tubes for longer?

    Sergei, testuję właśnie twoją metodę z wysokim napięciem. W artykule pisze żeby maksymalnie 5 minut dawać lampie. Czy te ograniczenie jest konieczne? Czy ty traktowałeś swoje lampy dłużej?
  2. RA1QEA

    RA1QEA Ham Member QRZ Page

    Lukasz, I kept the lamps under high voltage until the corona discharges in the lamp stopped and the minimum current through the lamp was set. This action took from one to two hours. Depends on the shelf life of the lamp, its old age.

    Lukasz, trzymałem lampy pod wysokim napięciem, dopóki wyładowania koronowe w lampie nie ustały i ustawiono minimalny prąd przez lampę. Ta akcja trwała od jednej do dwóch godzin. Zależy od okresu przechowywania lampy, jej starości.

    Good Luck!
  3. SP4IT

    SP4IT Ham Member QRZ Page

    Thanks. :)

    My tube had about 50uA of current with 10kV~12kV when I plugged it in for the first time. It is a lot concerning there was no grid leakage current after previous actions.

    I couldn't hear anything from inside the tube, but after 5 minutes anode current dropped to about 30uA. 25uA is the target with 10kV. My supply is "somewhere between 10kV and 12kV" depending on load, temperature etc.

    This tube is a GU-43B from 1983 (made in Russia).

    I also tested two Q-1Ps made in 1978 and 1979. Surprisingly the initial anode current was about 25uA from the start. I didn't notice any difference after few minutes so I stopped the treatment. However, in Q-1Ps I could definitely hear a "crackling like noise".

    I'm currently working on the amplifier so we'll see what happens when they are expected to work
  4. SP4IT

    SP4IT Ham Member QRZ Page

    Good news :)

    The tube I've been working on survived proper high voltage fine (3300V - even higher with no load, almost 4kV). I only used a little bit of HF drive resulting in ~200W because I didn't have a load padding cap rated for high current.

    So far it's looking good.
    AC9YY likes this.
  5. WA9SVD

    WA9SVD Ham Member QRZ Page

    HOW can an external anode be "external to the vacuum???"
  6. YO9FZS

    YO9FZS Ham Member QRZ Page

    Here it is.
    You can clearly see the getter pills (there are 8 of them) attached at the top of the screen grid cage...
    The gettering is done by the action of the heated cathode.

    GL & 73!

    Traian, YO9FZS

    SP4IT and KD2ACO like this.
  7. YO9FZS

    YO9FZS Ham Member QRZ Page

    Ha, ha!... The first who did it that way was me, almost 20 years ago!
    I had described my experiences at that time, see here:
    Probably the russian amateur found my old post while searching for info regarding the GU-43... he even use a tripling voltage rectifier from a old color TV exactly like I did and wrote about at that time...
  8. SP4IT

    SP4IT Ham Member QRZ Page

    Wow, that's pretty cool :)

    There is so much good stuff in this reflector's archive. I wish the search feature was a bit better.
  9. SP4IT

    SP4IT Ham Member QRZ Page

    That's a great photo. Thank you :)

    I just would like to make sure. Are you sure those "pills" are getters? I can't tell from the photo if the top surface is metal or a chemical (painted on, or sintered in).

    Also, it looks to me that they are on top of the metal ring connected to the screen, not cathode? I can't tell for sure at this resolution.

    Did you take the photo yourself? Do you have more perhaps? (with further disassembly, different angles) I would love to see them.
  10. YO9FZS

    YO9FZS Ham Member QRZ Page

    I got that picture from www. There are 8 pills of gray getter material attached to the top of the screen grid cage of that GU-43. That gettering material itself seem to be similar with the one attached in the close proximity of the anode for some GU-81 tubes (the two washer shaped ones in the picture below) which make sense if considering the similar temperature range of those areas.
    Some variation of gettering system may exist for the same type of ex-soviet tube, for example the GU-46 can be found with zirconium covering of anode only, while other samples of GU-46 are also using additional gettering pills attached to the anode cone... As you can see it seems they use different shapes of the same gray getter material...

    gu-81 getter.jpg

    SP4IT and AH7I like this.
  11. RA1QEA

    RA1QEA Ham Member QRZ Page

    Lukasz, To you for the future.
    If the lamp did not work, then the stamps circled with a blue square (OTK) should be dark-blue.

    Attached Files:

    Last edited: Feb 12, 2022
  12. RA1QEA

    RA1QEA Ham Member QRZ Page

    Sorry, I forgot.
    The stamp on the lamps is gray.
    The lamps worked for quite a long time.

    Attached Files:

    Last edited: Feb 12, 2022
  13. SP4IT

    SP4IT Ham Member QRZ Page

    Thank you. I didn't know that :)

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