![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgM737Soek3v5qtO3ugcuv-zAJY-LQLaWmaN7p-9QhZ8zbV5YtfiykB7UXGOgPmZ2hpNZRGPga4Yf00xp7Ai_mfMrUbg_ZkaHfCuM_6-dTWm1oAjfI5iyP45HmWmUd6sGbNA05t7_IHkx0/s320/80m-bpf.JPG) |
A band-pass filter for 80 meter band. |
The simple direct conversion receiver I built a while ago works great when used daytime but on the evenings it will get overloaded by broadcasters. Maybe I can cure that with a better Band-pass filter. So I built one. I used the values that I found at
W8DIZ site, but with some variation to fit what I had in the junk box. As you can see it is built 'ugly' on a PCB. I am using SMA connectors as I was able to buy a large number that probably will last for many years to come.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEZ-c_uLDTQpLWX1FK1rhyvDzmjTHtf97YR769LP9vILckp-NASCJR49v6nc4-juv6fzsa28JOryUH1z8zy68kh7Z9NJ6rlOrtwpwu0SMkzeduwFTJMtpGHsP7zFQCtEoxCeQnshykviM/s320/80m-bfp-mini-vna-pro.JPG) |
Tuning and measuring the band pass filter with the MiniVNA Pro |
Now using the miniVNA pro and the VNA/J software a can tune and align the filter as I want to have it. The nice thing is that you run the VNA continuously so I see right away on the screen how to filter looks like. This was the end result:
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPHURQG-x_eEG_St9JPnONQNtV12duCeSAE5_MJwAtmDe-JlriK6GLYd2wTA91f9h-81x1CWwLe9TpBc55GciALBtLQOIAtlVVVWHcjKSmJ15fiSFRfc_8Qyy7jjy_C8HmedCyA_8vGqA/s320/80m-bpf-mini-vna-pro.png) |
VNA/J showing the 80 m BPF curve |
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