homebrew ubitx roofing filter #bitx20help #bitx40help #bitx40 #bitx20 #filters


hello i have finished building the ubitx CM2KMK version and i have problems with the 45mhz crystal filter. the only filters i have in my inventory are the following--
22M03       45,1mhz     from a motorola GM300
49S10B     49,95 mhz   from a kenwood TK760
FL-210       21,8 mhz       from Icom M59
I have tested all of them by changing the frequency acording to each crystal in the source code.The best results so far i get with the 21.8mhz filter FL-210.
iI think the problem is matching the impedance with the two coils L5 and L7 i used 12 turns on T37-6 .
Please if someone have any documentation about the filters or knows what impedance they have i wil be very thankfull.
Thanks in advance ! 73de yo4huj

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