Cavity filter question

[Hopup]

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?

 

[73's de Edd]

not letting the dust etc in
Otherwise its a preferred nitrogen fill

 

[davenn]

I did open one cavity and I wonder if I did let some gas out what was necessary for its operation?

no, it isn't

I have couple quite big full copper cavity filters meant for Ghz range.

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

 

[Hopup]

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.

 

[Hopup]

Ok, theres some images of the cavities, last one is from other.

 

[davenn]

Ok, theres some images of the cavities, last one is from other.

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




Dave

 

[73's de Edd]

That's the last time that you will ever see it looking that good . . . .as they were assembled in an inert filler zone.

 

[Hopup]

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]

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.

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

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

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