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8640Jr – Band 3 Lowpass Filter

 

8640Jr – Band 3 Lowpass Filter

Filed in homebrew on May.19, 2012

There is a little distortion on the waveform of the Band 3 Low Pass Filter Output. The Spectrum Analyzer shows only about 14 db of attenuation on the 3rd harmonic of frequencies near the low end of the Range. This agrees with the predicted results below.

 

 
Band 3 Lowpass Filter Passband

The original design looks like this…

 

 
Band 3 Lowpass Schematic

The actual spectrum output looks like this on the low end of the range…

 

 
Band 3 Low Pass Filter Output Spectrum

Things look better on the high end of the range, and the waveform looks better there, as well.

 

 
Band 3 Lowpass Filter Output Spectrum - High End of Range

The predicted bandpass is as follows (10.5 mhz down about 15 db):

 

 
Band 3 Low Pass Filter Predicted passband

Here are the waveforms… For the Low End Frequencies:

 

 
Band 3 Low Pass Filter Output - Low End of Range

and for the High End…

 

 
Band 3 Low Pass Filter Output - High End of Range

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