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Re: [tracker2] Re: OT3m with Nuvi 350

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  • Scott Miller
    Any chance you ve got an oscilloscope to check what the audio level is? I can walk you through checking a few places if you d like. The trackers are all
    Message 1 of 19 , Feb 2, 2012
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      Any chance you've got an oscilloscope to check what the audio level is?
      I can walk you through checking a few places if you'd like. The
      trackers are all tested for RX before they leave, but it's always
      possible a solder joint failed or something.

      Scott

      On 2/2/2012 12:28 AM, Mads wrote:
      > Well, the FCS count actually increased to 4 after a few hours.
      >
      > 73! Mads, la1tpa
      >
      > --- In tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com>,
      > Scott Miller <scott@...> wrote:
      > >
      > > Then it's probably not getting any audio. Do you have another tracker
      > > or TNC that you can use to verify your cabling?
      > >
      > > Scott
      >
      >
    • Mads
      Actually I have an old oscilloscope collecting dust in the basement. It should be suitable for AF measurements. Please provide some (detailed) instructions on
      Message 2 of 19 , Feb 2, 2012
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        Actually I have an old oscilloscope collecting dust in the basement. It should be suitable for AF measurements. Please provide some (detailed) instructions on where to measure to the e-mail address on my qrz.com profile.

        73! Mads, la1tpa

        --- In tracker2@yahoogroups.com, Scott Miller <scott@...> wrote:
        >
        > Any chance you've got an oscilloscope to check what the audio level is?
        > I can walk you through checking a few places if you'd like. The
        > trackers are all tested for RX before they leave, but it's always
        > possible a solder joint failed or something.
        >
        > Scott
      • Scott Miller
        I m going to post this here so it s in the group archive. This applies to PCB v1.1 (note that there s a stray v1.0 marking in the lower left of the board - I
        Message 3 of 19 , Feb 7, 2012
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          I'm going to post this here so it's in the group archive. This applies
          to PCB v1.1 (note that there's a stray v1.0 marking in the lower left of
          the board - I only recently discovered that.)

          The RX section is in the upper left of the board, near the radio DB9
          connector. You should see the input signal at ferrite chip L4 (left of
          D5, not marked). C2 and/or C18 (depending on whether SJ2 is set) AC
          couple the signal to the op amp input. You should see the op amp input
          on the left side of R2. You'll see the output at R9, which connects by
          a fat trace to the ADC input on the microcontroller. The entire audio
          path stays on the top layer of the PCB, and it's pretty visible because
          the traces are wider than anything but the power traces.

          Some problems I've seen that prevent RX from working are bad solder
          joints on components in that section, an improper value for C11 (should
          be 22pF, can be removed without any real impact), and an improper value
          for either R8 or R11 (both should be 30k and the voltage at their center
          point should be 1/2 Vcc).

          Scott

          On 2/2/2012 10:29 AM, Mads wrote:
          > Actually I have an old oscilloscope collecting dust in the basement. It
          > should be suitable for AF measurements. Please provide some (detailed)
          > instructions on where to measure to the e-mail address on my qrz.com
          > profile.
          >
          > 73! Mads, la1tpa
          >
          > --- In tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com>,
          > Scott Miller <scott@...> wrote:
          > >
          > > Any chance you've got an oscilloscope to check what the audio level is?
          > > I can walk you through checking a few places if you'd like. The
          > > trackers are all tested for RX before they leave, but it's always
          > > possible a solder joint failed or something.
          > >
          > > Scott
          >
          >
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