[NLRS] WR-75 waveguide parts

[Dr. Gerald N. Johnson]

Those slots are placed right to absorb mostly second harmonic from the 
TE02 mode in the wave guide where the voltages would have two peaks with 
a minimum at the center of the wave guide, where the fundamental mode 
would have a voltage peak at the center of the wave guide in TE01 mode. 
Expecting to handle more than a few watts for either the coupler or the 
filter.

73, Jerry, K0CQ

On 3/25/2011 12:15 PM, Douglas H Reed wrote:
>
>
> 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
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