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Old 26th May 2021, 5:38 am   #12
Radio1950
Hexode
 
Join Date: Apr 2017
Location: Buderim, Queensland, Australia.
Posts: 370
Default Re: 1MHz output impedance query?

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If you are using an LC RF Filter for square to sine conversion, can I suggest you use an online calculator.

Sample filter circuit for your situation attached.

This was calculated with RF Tools "LC Filter Design Tool".
https://rf-tools.com/lc-filter/

I checked the sample circuit with the SimSmith analyser program to be OK, but values can be slightly optimised.
http://www.ae6ty.com/Smith_Charts.html

If you go ahead with this and have difficulty with making or testing the inductors, I can make them up for you and post them off FOC.
If you make a different design with different values, I can check the circuit then make up the inductors and post them off.
You may need to tell us the circuitry immediately before and after the filter, so I can adjust the filter source and load impedances for a final design.

If you make up the inductors yourself, I suggest using type 61 ferrite cores in 50 size (one half inch). The core may be marked "FT50-61".

I have not gone into some filter aspects deliberately, but you are in the right forum to ask questions, even very difficult (radio) ones.
I may not be the one to answer however.

Good luck
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