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2 Meter Band-Pass Filters for Front-End Overload

Discussion in 'Amateur Radio News' started by NJ7V, May 23, 2021.

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  1. AG6JU

    AG6JU Ham Member QRZ Page

    It is common problem that strong signal within even within + / - 20 , 30 MHz interfere , or desensitize. Cavity Pass filter 4 inch or more larger diameter has about 50 kHz to 100 kHz bandwidth, so you can use those, you can use those cavity filter for both transmit and receive. I used to put those cavity filters when I was working on two way radio system, suffering from desensitization from Pager TX so on. or you may experiment with making crystal ladder filter using inverted mesa crystal for those VHF frequencies. I made such filter once. -- > https://forums.qrz.com/index.php?threads/crystal-filter-using-inverted-mesa-crystals-143mhz.762953/
     
  2. WD8CRT

    WD8CRT Ham Member QRZ Page

    Baofeng? I bought one out of curiosity... you get what you pay for. Tossed it.

    If you know the offending freq, a coaxial notch filter works well... and only a fraction of the price of the Baofeng. Used them to notch out pagers and commercial 2 ways.
     
  3. LU1FDQ

    LU1FDQ Ham Member QRZ Page

     
  4. LU1FDQ

    LU1FDQ Ham Member QRZ Page

    I agree with Chip that it is a good experience, and I am learning a lot from everyone post.
    I had a Kenwood TH-78A, and it was imposible to be used in the city even with a quarter wave mobile antenna, not to day the Ringo in a tower; it captured every radiotaxi base transmitting in VHF, no matter the frequency you tune! It worked ok with the rubber duckie antenna.
    However, my older Kenwood TR-2500 worked fine with both antennas, mobile and Ringo, without any trace of interference! Of course it is less sensitive than the newer one; this last one looks like it was designed to use with rubber duckie only.
    73 & good luck.
     
  5. KG4RRN

    KG4RRN Ham Member QRZ Page

     

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