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4890Re: FT1000 MK5 Field / Icom radio IF panadapter.

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  • Lyle Koehler, K0LR
    Jun 1, 2006
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      On my original IC-706, I was able to tap into the circuit at the input
      to the 9 MHz filter. Since it appears to be a fairly low-impedance
      point, I simply coupled the signal through a 50 pF capacitor and
      brought out a short piece of RG-174 coax with an inline RCA phono
      connector. There is a ceramic roofing filter in the first IF at 69
      MHz. The service manual doesn't provide any information on the
      bandwidth, but it appears to be about 25 kHz. With my homebrew general-
      coverage SDR receiver set so that the center frequency comes out at 12
      kHz, the panadapter provides a +/- 12 kHz display. I noticed that with
      a fixed signal coming in, the output frequency jumps around depending
      on what mode you're using. Not a surprise, but it probably screws up
      the centering of the panadapter display if you want to use it in
      multiple modes.

      The output level on the 706 IF is not excessive; if anything, it could
      use a little more gain going into the SD receiver.

      Lyle, K0LR
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