CW Filter Model FR4


The FR4 filter is for use between receivers or transceivers, and high impedance headphones. It is a passive audio filter centered around 850 Hz. A switch is included to completely remove the filter from the headphone line for phone reception.


  • Center Frequency: 850 Hz
  • Bandwidth at 6 dB Down: 400 Hz
  • Bandwidth at 60 dB Down: 2.4 KHz
  • Input Impedance: 2000 ohms
  • Output Impedance: 2000 ohms
  • Insertion Loss: Less than 3 dB
  • Size: HWD 2-1/2" x 4-3/4" x 6"
  • Shipping Weight: 1 lb 12 oz
  • Finish: Baked enamel case, molded plastic side panels with wood grain inserts

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