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Ensemble RXTX stage 5 RF I / O voltage check failure p.28/30 of build

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  • jrutleseattle
    To recap the problem from last week Ensemble RXTX . All checks ok until stage 5 RF I/O and switching stage following this build:
    Message 1 of 2 , Jul 4, 2011
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      To recap the problem from last week
      Ensemble RXTX . All checks ok until stage 5 RF I/O and switching stage following this build:
      http://www.wb5rvz.com/sdr/ensemble/

      Results with 12.2 volts input:
      current draw of 1.55 mA (way below expected)
      voltages (expected 2.5 v)
      R62 = 5.25v
      R53 = 5.24v
      R54 = 5.24 v all against R50 the system ground


      point A default (expected 9-12 = 1.73
      Point B default (expected 0) = 5.2

      I got lots of great advice ( THANK YOU VERY MUCH) and pursed them as follows:

      1) PTT—was set for receive as best can tell via CFGSR software.
      2) ABPF was and confirmed to be disabled
      3) Values of R61 and R62 confirmed again at 1 K ohm . however both measure 800 ohms in place (they were confirmed at 1 k before insertion). (R61 voltage = 2.77) and then I replaced both with new resistors and got the same issue: 989 ohms before insertion, 808 after. Ohm meter calibrated fine with resistors not yet used.
      4) the R53 and R54 voltage of 5.24 instead of the expected 2.5 was attributed to the voltage divider not functioning properly.
      4) R61 and R62 appear to be properly soldered. However, I do not find continuity between either of their leads and R50 (Ground). ????? Should I??
      5) I do not see solder splashes or issues with pins 3 or 5 of U11. In fact it looks the best of all my connections. When mounted all voltages checked except pin 11 (expected 2.5) was 2.1 v which I thought might be a little at the edge of tolerance.
      6) I removed R61 and measured R 62 finding -7.7

      6) post replacement of R61 and R62 I measured the following with 12.2 volts input and the USB not connected:
      Hairpin of the below resistors to hairpin R50 (ground).

      R63 minus 7.7 (no , leads not reversed on multimeter I swear)
      R62 minus 5.25
      R61 minus 2.77
      R54 & R53 minus 5.25

      7) further measurements:
      U3-R11—o volts to ground on both RX and PTT.
      R36-R34=0.35 volts
      R51-R34 hiarpins: 3.48 RX and 10.74 TX
      R51 to R34 = 1.74
      Q3-B = 3.49
      R52 = 3.83 (impossible, input remeasured at 12.2 volts)
      R55 hole to ground = 0.0 volts

      If ground R63 to R50, I get 2.74 on R61 and 0.0 on R 62.

      I hope someone can make sense of the above measurements. I can not, muchless know where to go next.
      Thanks very much for sharing your expertise.

      Joe
      W7ESE
    • Alan
      ... Subject: [softrock40] Ensemble RXTX stage 5 RF I / O voltage check failure p.28/30 of build ... current draw of 1.55 mA (way below expected) This makes no
      Message 2 of 2 , Jul 5, 2011
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        ----- Original Message -----
        Subject: [softrock40] Ensemble RXTX stage 5 RF I / O voltage check failure
        p.28/30 of build


        >Results with 12.2 volts input:
        current draw of 1.55 mA (way below expected)

        This makes no sense. I can't see how it can be this low if all the ICs are
        in place.


        .

        >4) R61 and R62 appear to be properly soldered. However, I do not find
        >continuity between either of their leads and R50 (Ground). ????? Should I??

        R62 should have one end grounded. So, yes resistance on these should be a
        max of 2K to ground.

        5) I do not see solder splashes or issues with pins 3 or 5 of U11. In fact
        it looks the best of all my connections. When mounted all voltages checked
        except pin 11 (expected 2.5) was 2.1 v which I thought might be a little at
        the edge of tolerance.
        6) I removed R61 and measured R 62 finding -7.7

        6) post replacement of R61 and R62 I measured the following with 12.2 volts
        input and the USB not connected:
        Hairpin of the below resistors to hairpin R50 (ground).

        >R63 minus 7.7 (no , leads not reversed on multimeter I swear)
        R62 minus 5.25
        R61 minus 2.77
        R54 & R53 minus 5.25

        Is R50 hairpin actually grounded? Is it soldered properly? Does it show 0
        Ohms to other ground points?

        There is something basically wrong here. You are not getting sensible
        readings.

        73 Alan G4ZFQ
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