So I decided to built a new one for 23cm band. After some searching on the internet, I found the following drawing of an interdigital filter from Daan PA4DAN.
http://pa4dan.nl/ham/homebrew/23cm_filter/
As I get a lot of aluminum parts, After a quick look in the garage, I found exactly the main piece of aluminum that I needed. Inner section 54 x 28mm.
The rest of the pieces are easy to find.
Hop. Cutting, drilling, tapping and ... settings on the spectrum analyzer.
Surprise! In less than 15 minutes the result are visible on the pic ... beyond my expectations !!
1296.1 Mhz = 0.85 dB, and a very narrow bandwidth.
Look at the picture ...
A nail polish stamped at XYL to block the screws and finished!
I am really happy with this home made construction.
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| Results of the new one |
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| First Filter |
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| Results of first filter |