Sunday 22 August 2021

LPF for 70 MHz

The RF output of my 28 - 70 MHz transverter shows an irritating 3rd harmonic at 210 MHz. 

I found a simple Low Pass Filter for 70 MHz at dutchrfshop.nl 

The filter should be able to handle RF powers up to 150 Watts.

4 ATC capacitors and 3 coils is all you need:


Arranged on a PCB as follows:



Some finetuning using the nanoVNA shifted the dip @ 70 MHz;


Next step is to test the LPF with the transverter..

Off-topic: Old QSL card







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