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Revision E testing

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  • Scott Miller
    I got the first batch of Proto E boards in, and built up six of them for testing. Like Proto D , it s the same form factor as the previous revisions but
    Message 1 of 7 , Aug 2 5:24 PM
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      I got the first batch of Proto 'E' boards in, and built up six of them
      for testing. Like Proto 'D', it's the same form factor as the previous
      revisions but the components are all surface mount, with the exception
      of the connectors, crystal, and LEDs.

      Changes from previous revisions include:

      - No tuning pot. In my testing, I found that there wasn't any real
      benefit to being able to adjust the RX tuning, compared to having it set
      with a precision resistor to the calculated optimum value. It seems to
      perform well across the whole temperature range, and it eliminates one
      of the more failure-prone parts.

      - Active RX filter. This takes the place of the passive filter network,
      and seems to squeeze a bit more performance out of the demodulator.
      Proto 'D' had a quad op amp, but Proto 'E' just has a single op amp in
      an SOT-23 package.

      - Ferrites on all off-board signals to reduce RFI.

      - Red and green LEDs in the TX and RX holes instead of pots. A solid
      green LED on receive, separate from the activity LED, makes it easier to
      see what's going on and frees up the ACT LED for other signals.

      - Jumper arrangement changed to match the OT1+, with the exception of an
      EQ jumper in place of A1/A2. This eliminates a few assembly steps and
      takes up less space.

      So far, performance is looking good. I did discover something
      interesting - if you remove the 510k resistor, it actually seems to
      improve RX performance a bit. I haven't confirmed if this works on the
      previous versions, and testing is inconclusive so far on the T2-135.

      I was just looking over my test result archives, and it occurs to me
      that the decode performance is better than any other '2211-based TNC
      I've seen, so maybe it's time to finally declare it 'good enough' and
      get this thing in production!

      Scott
    • rubines2000
      Hi Scott Is there a chance you will sell also unpopulated pcbs? I would buy one immediately. Cheers Michael OE1MIS ... set ... network, ... easier to ... of an
      Message 2 of 7 , Aug 3 7:14 AM
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        Hi Scott

        Is there a chance you will sell also unpopulated pcbs?
        I would buy one immediately.

        Cheers
        Michael OE1MIS

        --- In tracker2@yahoogroups.com, Scott Miller <scott@...> wrote:
        >
        > I got the first batch of Proto 'E' boards in, and built up six of them
        > for testing. Like Proto 'D', it's the same form factor as the previous
        > revisions but the components are all surface mount, with the exception
        > of the connectors, crystal, and LEDs.
        >
        > Changes from previous revisions include:
        >
        > - No tuning pot. In my testing, I found that there wasn't any real
        > benefit to being able to adjust the RX tuning, compared to having it
        set
        > with a precision resistor to the calculated optimum value. It seems to
        > perform well across the whole temperature range, and it eliminates one
        > of the more failure-prone parts.
        >
        > - Active RX filter. This takes the place of the passive filter
        network,
        > and seems to squeeze a bit more performance out of the demodulator.
        > Proto 'D' had a quad op amp, but Proto 'E' just has a single op amp in
        > an SOT-23 package.
        >
        > - Ferrites on all off-board signals to reduce RFI.
        >
        > - Red and green LEDs in the TX and RX holes instead of pots. A solid
        > green LED on receive, separate from the activity LED, makes it
        easier to
        > see what's going on and frees up the ACT LED for other signals.
        >
        > - Jumper arrangement changed to match the OT1+, with the exception
        of an
        > EQ jumper in place of A1/A2. This eliminates a few assembly steps and
        > takes up less space.
        >
        > So far, performance is looking good. I did discover something
        > interesting - if you remove the 510k resistor, it actually seems to
        > improve RX performance a bit. I haven't confirmed if this works on the
        > previous versions, and testing is inconclusive so far on the T2-135.
        >
        > I was just looking over my test result archives, and it occurs to me
        > that the decode performance is better than any other '2211-based TNC
        > I've seen, so maybe it's time to finally declare it 'good enough' and
        > get this thing in production!
        >
        > Scott
        >
      • Chris Kantarjiev
        ... Um, do tell. I d love to do anything I can to improve the receive performance of the Proto C at CDRVLY; it s in a rather marginal location, but the only
        Message 3 of 7 , Aug 3 8:53 AM
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          >
          >
          > So far, performance is looking good. I did discover something
          > interesting - if you remove the 510k resistor, it actually seems to
          > improve RX performance a bit. I haven't confirmed if this works on the
          > previous versions, and testing is inconclusive so far on the T2-135.

          Um, do tell. I'd love to do anything I can to improve the receive
          performance of the Proto C at CDRVLY; it's in a rather
          marginal location, but the only igate in "sight" of the valley.

          73 de chris K6DBG
        • Curt, WE7U
          ... I was thinking the same thing... But don t want to take a bunch of Scott s time tweaking the old units to maximize performance. If there are easy tweaks
          Message 4 of 7 , Aug 3 9:08 AM
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            On Fri, 3 Aug 2007, Chris Kantarjiev wrote:

            > Um, do tell. I'd love to do anything I can to improve the receive
            > performance of the Proto C at CDRVLY; it's in a rather
            > marginal location, but the only igate in "sight" of the valley.

            I was thinking the same thing... But don't want to take a bunch of
            Scott's time tweaking the "old" units to maximize performance.

            If there are easy tweaks that would translate to the Proto-A or
            Proto-C units, I'd like to hear about them.

            --
            Curt, WE7U: <www.eskimo.com/~archer/> XASTIR: <www.xastir.org>
            "Lotto: A tax on people who are bad at math." -- unknown
            "Windows: Microsoft's tax on computer illiterates." -- WE7U
            The world DOES revolve around me: I picked the coordinate system!
          • Scott Miller
            You can try clipping the 510k resistor, see if that makes any difference. Also, I replaced the 51k resistor with 100k and it seemed to make a slight
            Message 5 of 7 , Aug 3 12:59 PM
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              You can try clipping the 510k resistor, see if that makes any
              difference. Also, I replaced the 51k resistor with 100k and it seemed
              to make a slight improvement. Both of those seem to affect the slew
              rate on the output of the 2211's FSK comparator.

              Scott

              Curt, WE7U wrote:
              >
              >
              > On Fri, 3 Aug 2007, Chris Kantarjiev wrote:
              >
              > > Um, do tell. I'd love to do anything I can to improve the receive
              > > performance of the Proto C at CDRVLY; it's in a rather
              > > marginal location, but the only igate in "sight" of the valley.
              >
              > I was thinking the same thing... But don't want to take a bunch of
              > Scott's time tweaking the "old" units to maximize performance.
              >
              > If there are easy tweaks that would translate to the Proto-A or
              > Proto-C units, I'd like to hear about them.
              >
              > --
              > Curt, WE7U: <www.eskimo.com/~archer/> XASTIR: <www.xastir.org>
              > "Lotto: A tax on people who are bad at math." -- unknown
              > "Windows: Microsoft's tax on computer illiterates." -- WE7U
              > The world DOES revolve around me: I picked the coordinate system!
              >
              >
            • Scott Miller
              I d rather not. Mostly because of the documentation and support requirements, but you d also have to hit 3 or 4 different distributors to get the required
              Message 6 of 7 , Aug 3 1:05 PM
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                I'd rather not. Mostly because of the documentation and support
                requirements, but you'd also have to hit 3 or 4 different distributors
                to get the required parts if you go by my BOM, or you'd have to find
                substitutes. You'd also need a MON08 pod to program the chip once the
                board is assembled.

                Oh yeah, that's another change I forgot to mention. Proto D and the
                T2-135 both have in-circuit programming connectors, but Proto E is the
                first board with a standard MON08 16-pin header, so you can use it with
                a debug pod without an adapter. Not that anyone aside from me is
                necessarily going to use it, but it's there.

                Scott

                rubines2000 wrote:
                >
                >
                > Hi Scott
                >
                > Is there a chance you will sell also unpopulated pcbs?
                > I would buy one immediately.
                >
                > Cheers
                > Michael OE1MIS
                >
                > --- In tracker2@yahoogroups.com <mailto:tracker2%40yahoogroups.com>,
                > Scott Miller <scott@...> wrote:
                > >
                > > I got the first batch of Proto 'E' boards in, and built up six of them
                > > for testing. Like Proto 'D', it's the same form factor as the previous
                > > revisions but the components are all surface mount, with the exception
                > > of the connectors, crystal, and LEDs.
                > >
                > > Changes from previous revisions include:
                > >
                > > - No tuning pot. In my testing, I found that there wasn't any real
                > > benefit to being able to adjust the RX tuning, compared to having it
                > set
                > > with a precision resistor to the calculated optimum value. It seems to
                > > perform well across the whole temperature range, and it eliminates one
                > > of the more failure-prone parts.
                > >
                > > - Active RX filter. This takes the place of the passive filter
                > network,
                > > and seems to squeeze a bit more performance out of the demodulator.
                > > Proto 'D' had a quad op amp, but Proto 'E' just has a single op amp in
                > > an SOT-23 package.
                > >
                > > - Ferrites on all off-board signals to reduce RFI.
                > >
                > > - Red and green LEDs in the TX and RX holes instead of pots. A solid
                > > green LED on receive, separate from the activity LED, makes it
                > easier to
                > > see what's going on and frees up the ACT LED for other signals.
                > >
                > > - Jumper arrangement changed to match the OT1+, with the exception
                > of an
                > > EQ jumper in place of A1/A2. This eliminates a few assembly steps and
                > > takes up less space.
                > >
                > > So far, performance is looking good. I did discover something
                > > interesting - if you remove the 510k resistor, it actually seems to
                > > improve RX performance a bit. I haven't confirmed if this works on the
                > > previous versions, and testing is inconclusive so far on the T2-135.
                > >
                > > I was just looking over my test result archives, and it occurs to me
                > > that the decode performance is better than any other '2211-based TNC
                > > I've seen, so maybe it's time to finally declare it 'good enough' and
                > > get this thing in production!
                > >
                > > Scott
                > >
                >
                >
              • dk7xe
                Hi Scott, all, ... on the ... anyone who can confirm that removing the 510k brings really RX performance improvement on the older revisions? BTW: got my 2 OT2
                Message 7 of 7 , Aug 17 12:59 AM
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                  Hi Scott, all,
                  > >
                  > > So far, performance is looking good. I did discover something
                  > > interesting - if you remove the 510k resistor, it actually seems to
                  > > improve RX performance a bit. I haven't confirmed if this works
                  on the
                  > > previous versions, and testing is inconclusive so far on the T2-135.
                  >
                  > Um, do tell. I'd love to do anything I can to improve the receive
                  > performance of the Proto C at CDRVLY; it's in a rather
                  > marginal location, but the only igate in "sight" of the valley.
                  >
                  > 73 de chris K6DBG
                  >
                  anyone who can confirm that removing the 510k brings really RX
                  performance improvement on the older revisions?

                  BTW: got my 2 OT2 revD kits on Tuesday. Did assembly of one in a 2
                  hour Morning session before going to work on Wed. Everything is
                  working perfectly (see http://map.findu.com/dk7xe-8). Really a great
                  device.

                  73' Gerald
                  dk7xe/oe6dld
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