The first day of 2018 seemed like a good day to try to figure what I did wrong when I built my QRX. I started with the LPF. Once again I pulled C29 and connected the tracking generator to the intersection of C29, C27, and L3. I did this a month or so ago and got a peak. Someone rightfully pointed out that a peak is not good for a LPF. So I did the test again and things look somewhat better.
The filter starts to roll off at about 4.35MHz
3dB down is about 4.92 MHz
By 20m it's about 20dB down
Now is a good time for someone to teach me about passband filters :o)?
The amateur radio 80m band is 3.5MHz - 4MHz. Wouldn't it be better if the filter rolled of closer to 4MHz?
Pics of the setup. You can see the marker between 4.330000 and MHz on the left side of the screen
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73
NE5U
Mike
