You can try calculating the values for a simple filter or use the digikey calculator here
There are several calculators around that will give you several poles depending on the accuracy you want.
Then draw the appropriate Inductor /Capacitance in LTspice with a voltage source and a 50 ohm load.? Don't forget the ground. Right click on the voltage source and put a 1 where it says ac amplitude. Then go? to simulate, edit simulation card and select ac analysis.? Select type of sweep: Decade. Start freq 100, stop freq 1 Meg.? Be sure to type Meg because M will give you 1000.? ?Now run and it should draw a bode plot of the filter.
Andy KM4TRT
