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Re: Revision E testing

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  • 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 1 of 7 , Aug 3, 2007
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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 2 of 7 , Aug 3, 2007
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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 3 of 7 , Aug 3, 2007
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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 4 of 7 , Aug 3, 2007
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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 5 of 7 , Aug 17, 2007
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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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