DIY Narrow Band Crystal Bandpass Filter

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I am planning to make a receiver recently, and I will use 21M15A crystal to convert the frequency to the intermediate frequency. The frequency is 21.4MHz.
The data shows that the bandwidth is ±7.5KHz.
The difference loss is about 2db,
and the fluctuation is 0.5db .
Next is the result of my debugging. It happened that I just got the vector network recently, and I started debugging.
I have seen people debugging on the Internet before, and I asked them, but they rolled their eyes...
Since then, I swear that what you can make, I can also debug it, but it’s just a matter of time. You take an hour, and I can use a day to debug it. Now I will share my debugging results with everyone. The crystal filter is nothing special, the main thing is to match the input and output ports with the instrument, this is the most important.
I use two-stage crystal cascade, just to try the effect first. This can be debugged, and multi-stage cascade is not a problem, it can definitely be debugged.
The circuit diagram is as follows

The main thing is that the input and output inductors and capacitors must match the instrument's ports. The values ​​of the crystal inductors and capacitors are different for different frequencies, but the models are almost the same.
The inductors and capacitors in the middle can be understood as adjusting the bandwidth.
I adjusted it to 1:30 a.m. last night, and the final result was not very ideal, it was a bit large, and it will be improved later.
Here are a few pictures

This is the 3db bandwidth, 40db bandwidth and 60db bandwidth within the passband. I have marked them all. You can tell at a glance.

This is the intra-band fluctuation. It looks pretty flat.

Finally, the out-of-band suppression is also good. I think the effect will be better if it is cascaded. I will continue to improve it later...

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