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10619Re: Bandwidth ??

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  • Dan
    Jul 4, 2013
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      Thanks Andy, I think I follow what you're saying.

      I made some sense of this...I tried a QSO on JT9, with VFO A set at 14.076 I answered a CQ call. VFO B showed 14.078. The TX cursor was a 3709 hz. When I logged the QSO I noted the log frequency showed 14.081.709. That's what I would have expected so was good to verify my thinking was correct. So some progress is being made on my part.

      One other thing I've noticed on the waterfall, JT65 signals appear to show from 600 to below 2000 usually, but occasionally I see them above 2000. JT9 signals appear to fall in the 2700 to 3800 range. With the JT65-JT9 blue marker set at 2000 the decoded signals seem to be in the correct section of the waterfall.

      Sure hope I'm doing this right...


      Dan
      KJ6RGX


      --- In wsjtgroup@yahoogroups.com, "k3wyc" <a.durbin@...> wrote:
      >
      > > Still trying to get my head wrapped around this...
      >
      > The VFO indicates the suppressed carrier frequency not the modulated RF frequency.
      >
      > The VFO B frequency increments in 1000 Hz steps as you move the TX cursor up the waterfall. Within each of those 1000 Hz windows the audio moudulation frequency will rage from suppressed carrier frequency + 1000 Hz to suppressed carrier frequency + 2000 Hz.
      >
      > If you have a second receiver then TX into a dummy load while listening to the transmitted signal on the other rig. Move the TX cursor up the waterfall in steps making a transmission at each point. If your receiver is fixed at VFO A freq you'll hear the received tone progressively increase in frequency regardless of the VFO B transmit freq. You won't be able to hear where the VFO B step changes are.
      >
      > However, if you listen to the tones being sent to the transmitter, you'll hear that they follow a sawtooth pattern, with freq increasing up to the point VFO B switches and then dropping down to start the next ramp up.
      >
      > Remember that if you transmit a single tone with an SSB rig in USB mode, the signal will have an RF frequency of suppressed carrier freq + tone modulation freq. You can put that rf signal at the same frequency with an almost infinite number of combinations of suppressed carrier frequency and modulation frequency.
      >
      > 73,
      > Andy k3wyc
      >
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