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Re: T2-301 transmitting strangely

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  • zl1vfo
    The three files are here -:
    Message 1 of 6 , Apr 29, 2011
    • 0 Attachment
      The three files are here -:

      What you can't see in the screen shots, but can hear in the .WMA audio sample is the 60Hz hum present. Doesn't sound like a 'clean' hum either = there's at least 4 or 5 harmonics in it that I can hear too so it may be a power supply issue if it /isn't/ a switch mode power supply feeding everything.

      Either that hum crept in while you were recording it, or there is a hum loop or a lack of audio earth between things.

      If testing the power supply doesn't reveal anything (i.e try substituting a 12V battery), then you can try wiring things in a 'star' configuration - make one thing (if possible) the centre of the 'star' and then just have the leads go from it to the other devices off the ends of the star - the idea is not to create any earth/hum loops. Sometimes this wiring arrangement just isn't possible, what with what things have to join to other things, but you can see what may be possible.

      Also, while I think of it, the device with the heaviest current draw should probably be the centre of the 'star', as higher current flows cause higher voltage drops across cables, meaning more potential for hum.

      Ian ZL1VFO

      --- In tracker2@yahoogroups.com, "pb648174" <yahoo@...> wrote:
      > It tried that and it didn't make a difference.. I then tried different receiving radios and other things until it hit me that the wall power supply I'm using to power the T2 I hadn't used before. I plugged it into a battery and it worked fine. So I guess something about this power supply doesn't work well with the T2, maybe it's too noisy or something, it was pretty cheap. Learn something every day.
      > --- In tracker2@yahoogroups.com, Scott Miller <scott@> wrote:
      > >
      > > I don't see the files there... but in any case, there's not much to tune
      > > since it's digitally synthesized. I have at least once seen the sine
      > > wave table in flash get corrupted, though, so I'd suggest reloading the
      > > firmware to see if that makes any difference.
      > >
      > > Scott
      > >
      > > On 4/29/2011 6:57 AM, pb648174 wrote:
      > > > My T2-301 has been working fine for a while and even yesterday morning
      > > > was working fine. However, later yesterday it started transmitting
      > > > strangely and I'm unable to decode its transmissions anymore, nor see
      > > > them decoded by APRS repaters in the area. I haven't done anything
      > > > different than how I've been using it for weeks so I don't think
      > > > anything I've done would have caused this.
      > > >
      > > > Here is a multipsk screenshot of an APRS message received (sound file
      > > > from wikipedia), with the data peak in the 2200hz area
      > > > http://f1.grp.yahoofs.com/v1/ULa6TVj4AzWbcVwFLQL6wqMO2x2lrR9zd5vg-Z_zvX2TKgjBHih8sZHIenWw3C-e6o71OfFshSdh0Q8RviN103NVvXuVTWg/SampleReceived.png
      > > >
      > > > Here is a multipsk screenshot of me receiving a bad T2 transmission, the
      > > > exact same data as the "reference" APRS transmission above, no 2200hz peak
      > > > http://f1.grp.yahoofs.com/v1/ULa6TS8qLDybcVwFE-N62BMq7ctbydEbq9V_l29f9zMnTwuRw1Nfgh5ZnW0kJp4bMkwFmVJCNRl8zxzhHhORSelI_GfzVE4/T2Received.png
      > > >
      > > > Here is an audio recording of the bad T2 message
      > > > http://f1.grp.yahoofs.com/v1/ULa6TRlpTRmbcVwFVrjtuYfXwhjklTGn03f5Us4AzBwdUcQl2Aoo27GlMK2d_pRyYVWEGJYnQkf-dWSb965FeJPTesDDSes/T2Received.wma
      > > >
      > > > I'm hoping there is some setting that maybe just got out of tune that I
      > > > can adjust and don't have to send it in for repair..
      > > >
      > > >
      > >
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