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Re: [tracker2] Re: Revision E testing

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  • 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 1 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 2 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 3 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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