[NLRS] WR-75 waveguide parts

[Douglas H Reed]

Yes, it should work OK at 10.368 if anyone is using waveguide there.
But I don't think it can be an isolator. I have quite a few of them
and this isn't one. No ferrite and no magnet.

But it may not be an attenuator either. That was my first guess. But
now that you reminded me it was on a PA, there is a chance it is a
harmonic trap or low-pass of some sort.

Looking down the inside, there are a series of thin slots cut in the
wide side wall, closely spaced, possibly 15 or more on each side where
the fins are. But the cuts are not full height of the wall, they are
two shorter slots spaced across the wall. Maybe I can do an ASCII
picture....
________FINS___FINS_______FINS____FINS______
|
|             | | | | | | | | | | | |             | | | | | | | | | | | | |
|
|             | | | | | | | | | | | |             | | | | | | | | | | | | |
|_____________________________________________
              FINS     FINS             FINS       FINS

I can't really show it right since the fins are on the same wall as
the slots. Anyway, it has to be setup to dissipate power because of
the fins but it isn't enough heat sink for major power. I can bring it
with for the NLRS table and first person to properly name it could
take it home.....

73, Doug Reed, N0NAS.

On Fri, Mar 25, 2011 at 11:29 AM, Dr. Gerald N. Johnson
<geraldj at weather.net> wrote:
>
> The finned unit is likely an isolator for a 14 GHz Pa. I don't know it
> can be moved to 10 GHz, the usual technique to move frequency of a
> circulator or isolator is to change the magnetic field on the ferrite
> device in the middle.
>
> WR75 works decently at 10 GHz, just the guide wave length changes more
> rapidly with frequency than it does at 10.368 GHz for WR90. Lots of TV
> LNB use WR75 at the input.
>
> 73, Jerry, K0CQ