[MAMS] 24 GHz waveguide filter Yo Dave

[M Ragouzis]

Hi Dave and all

I have a millimeter scale on the digital read out if you need holes drilled in 
wave guide / K&S tubing ?

Mike



________________________________
From: Lloyd Ellsworth <l10368r1 at yahoo.com>
To: MAMS <mams at mailman.qth.net>
Sent: Sat, December 18, 2010 11:49:56 AM
Subject: [MAMS] 24 GHz waveguide filter

Dave, 

Every now and then, you run into one for sale. 

Charles Suckling, G3WDG, has a good construction article on HB one using WR42 
waveguide. About 4 inches long as I recall. Alignment is a bit of work. But it 
works. I may have a copy of his construction article somewhere. Likely, you can 
substitute some K&S hobby brass rectangular tubing and make it work. Early 
experiments ran with WW8M, showed it to work. Nearest K&S Brass size works out 
to WR34. But the spacing is the same on the holes and iris. Mounting brass 
screws is tricky because the brass is thin. Does not take much heat. Warps easy. 
We made a pile of Home brew waveguide transitions. I wrote up an article on that 
for MUD some years ago. Still using them. Still making them. Takes me about 4 
hours. W2PED has/had some very nice transitions available. 


I had some WR42 for sale, and standard 4 hole flanges, but don't know if I have 
any waveguide left. I might have a couple extra flanges. WR42 is not as common 
as WR90, and it is more expensive. Then the effects of the price of scrap copper 
these days. 


Dayton, and MUD, I have found some extra home brew wave guide filter units FS. 
Usually, extra made, then keep the best one. 


Germany, Henrik the Machineist, and Pale OZ8AFC in Denmark, make some really 
nice professional ones. Silver plated. About $100. Adjustment is pretty straight 
forward. Cavity design. Also 47 GHz. That is what I eventually graduated to. I 
use them now. Low insertion loss, and performs well. 


Testing is a bit of a trick. All about the available test equipment. 

P.S. Plenty of SMA relays, work on 24 GHz. However, you have to test them first. 
Find out if they do, and if the losses and performance are acceptable. Same with 
SMA connectors. K type SMA are what you want for 24 GHz. But they are a bit 
scarce and pricey. UT.085 is rated to 65 GHz. I would compare using a SMA on 24 
GHz, about like using a PL259 on 2M. Not the best, but it will work. Get you on 
and going. Later as the proper surplus, or parts become available, or affordable 
then upgrade. 


Also the Dish Network Dishes. Work just fine. So do the DH dishes. Also wrote up 
an article for MUD, for a HB affordable dish feed for 24 GHz. Used a .310 empty 
brass casing, and solder up a bit of UT.085. Called it the "Detroit" special. 


Big problem you learn about 24 GHz and up. Lead solder absorbs RF. It becomes a 
problem. Minimize use. 


Good luck. 

73, Lloyd NE8I/r
EN74 etc




      
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