Connect with us

Cavity filter question

Discussion in 'Radio and Wireless' started by Hopup, Jun 27, 2018.

  1. Hopup

    Hopup

    226
    30
    Jul 5, 2015
    I have couple quite big full copper cavity filters meant for Ghz range. There are lot of screw which seal the cavities very tightly. Do the cavities have some gas like hydrogen inside of them for better propagation or is it just for not letting the dust etc in?

    I did open one cavity and I wonder if I did let some gas out what was necessary for its operation?
     
  2. 73's de Edd

    73's de Edd

    2,723
    1,114
    Aug 21, 2015
    not letting the dust etc in
    Otherwise its a preferred nitrogen fill
     
    Last edited: Jun 27, 2018
    Hopup likes this.
  3. davenn

    davenn Moderator

    13,314
    1,766
    Sep 5, 2009

    no, it isn't

    when you said that ... I thought to myself ... that sounds a contradiction .... big and GHz don't usually go together
    unless it was low GHz --- 1 to 3 GHz. Anything from around 5 GHz and up, the cavity filters are very small

    out of interest, I would like to see a pic or 2 ... radio comms is a major work and hobby interest of mine





    Dave
     
  4. Hopup

    Hopup

    226
    30
    Jul 5, 2015
    Yeah devices are low GHz range. They look big for me, but I'm sure sub Ghz range are far larger.

    Device I opened has lot of resonator masses? inside of it which are adjustable, they move up and down. And the cavity is like 22-25cm and its made of smaller chambers. Got this one really cheap for parts mainly. I will put couple pics when I got time.
     
  5. Hopup

    Hopup

    226
    30
    Jul 5, 2015
    Ok, theres some images of the cavities, last one is from other.

    IMG_7036 - Copy.jpeg IMG_7037 - Copy.jpeg IMG_7038 - Copy.jpeg IMG_7039_Copy.jpeg
     
    davenn likes this.
  6. davenn

    davenn Moderator

    13,314
    1,766
    Sep 5, 2009

    ohhhh VERY cool :)

    can you please give some dimensions

    eg in that last image …. how tall are those posts ? …. the dimensions of the cavities X and Y

    IMG_7039.jpg.jpg


    Dave
     
  7. 73's de Edd

    73's de Edd

    2,723
    1,114
    Aug 21, 2015
    That's the last time that you will ever see it looking that good . . . .as they were assembled in an inert filler zone.
     
  8. Hopup

    Hopup

    226
    30
    Jul 5, 2015
    They do look very cool I agree, cavities are roughly around x = 4.5cm y= 4.1cm and those posts are around 2.5cm height diameter 1cm. Other pictures, the cavities are little bit bigger in size.

    Yeah I know they will be contaminated by opening them but I don't plan using these ones for anything of serious purpose.
     
    davenn likes this.
  9. davenn

    davenn Moderator

    13,314
    1,766
    Sep 5, 2009

    OK :) those measurements could easily put them up around to 2 - 3 GHz region,


    as long as any dust was blown out, the cavities would still work the way they should …. as is, it would make a nice talking piece displayed on a workbench shelf :)


    Dave
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-