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Home made Duplexers

Erik Westgard
 

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Alan Knutson WB0ZKB has been making 1.2G duplexers and triplexers for us out of 4” aluminum square tubing.? The cans are about 4 ? inches high. We need to get an article published on how he does this.

Erik NY9D ??
 

If you have any 1.2 Ghz duplexer or triplexer designs please forward to the group. Thanks! Dean K9PT
 

I did a periodical search on the topic and nothing came back.? I would assume most would just just vertical antenna spacing to achieve the isolation in lue of a duplexer.? Just 10-15 feet of separation at that high of a frequency should yield you adequate isolation.
 

I knew I read something on the topic.

dstar.ca once had some technical info concerning duplexers, multicouplers

https://web.archive.org/web/20090103211759/http://www.dstar.ca/hardware.html

Do any better mirrors exist of this page?
 

Here is where the site moved to:

http://www.bcfmca.bc.ca/dstar/hardware.html
 

Great duplexer info on that site. Their focus seems ?to be on the loop in the top of the duplexer. I still have not found info on what a TX/RX loop looks like.


As to going vertical, our antenna is on a building parapet, no way to put one above it.


As to the length being the same as a 440 MHz?can, ours are 800 MHz so without an actual measurement I still don't know where to start.


Thanks again for the support guys, keep the comments coming.


Rex AJ4GC
 

I thought I would add that I am still working on this 1.2 GHz duplexer project.
I removed the original plungers and cut 1/2" off of the outer shell, then sawed the slots down another 1/2".
The cans now tune up past 1.3 GHz.

Now I am trying to work out the correct coax lengths to align the notches and get the insertion loss down.
I am using coax during the trial and error part (mostly error) but will replace with 1/4" hardline when I have the electrical lengths resolved.

Rex AJ4GC

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