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Re: [softrock40] QSE Key input?

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  • Bill Dumke
    Tony, My M-Audio Delta 44 for 96 kHz sample rate is specified at: Input: +/- 0.4 dB, 22Hz - 40 kHz Output +/- 0.3 dB, 22 Hz - 40 kHz (Note the decimal points.)
    Message 1 of 15 , Sep 23, 2006
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      Tony,

      My M-Audio Delta 44 for 96 kHz sample rate is specified at:

      Input: +/- 0.4 dB, 22Hz - 40 kHz
      Output +/- 0.3 dB, 22 Hz - 40 kHz

      (Note the decimal points.)

      My Sound Blaster Audigy 2 is specified at:

      Frequency Response = < 10 Hz to 46 kHz (1V, 2V Rated Output) (+/- 3 dB,
      24-bit/96 kHz input)

      (No decimal point. So I can see where the Audigy 2 could be rolling off
      faster than the Delta 44.)

      I have a SoundMax on my 3 year old ASUS motherboard as well. Mine uses
      an AD1985. It is specified at:

      Analog Output Passband: 2-20,000 Hz

      (I assume 3 dB down.)

      So I can see why you ran into the problem.

      Bill WB5TCO

      Tony Parks wrote:
      > Hi Bill,
      >
      > The line-out BW is still a question needing to be answered for various
      > soundcards. My tests used the SoundMAX mother board soundcard in my PC and
      > I noted that the RF output of the v6 exciter was pretty constant out to 20
      > kHz and then started falling off quickly around 21 kHz. Also the sideband
      > suppression really fell apart above 20 kHz offfset from the center
      > frequency. The soundcard line-out BW is designed for the frequency range
      > needed for audio playback so it may be that 20 kHz BW is pretty standard.
      > This may be a limitation on a SoftRock type exciter that people will be
      > unhappy with. Additionally there is a little bit of spectrum lost around
      > the center frequency.
      >
      > 73,
      > Tony KB9YIG
      >
      > ----- Original Message -----
      > From: "Bill Dumke" <billd@...>
      > To: <softrock40@yahoogroups.com>
      > Sent: Saturday, September 23, 2006 7:22 PM
      > Subject: Re: [softrock40] QSE Key input?
      >
      >
      >
      >> Tony,
      >>
      >> Thanks for the info, Tony. The numbers are good for something this
      >> simple.
      >>
      >> Does anyone know if it is possible to get +/- 40 kHz or more IQ audio
      >> out of a sound card with a fast PC? I was wondering why they stopped
      >> at +/- 20 kHz .
      >>
      >> Bill WB5TCO
      >>
      >> Tony Parks wrote:
      >>
      >>> Hi Bill,
      >>>
      >>> IQ GEN provides the quadrature audio outputs from line-out needed for QSE
      >>> testing. Use only the upper amplitude and frequency sliders on the IQ
      >>> GEN
      >>> window. The lower amplitude slider needs to be set to zero. The usec
      >>> adjust slider at the bottom of the window provides a fixed time
      >>> correction
      >>> between the I and Q signals. As frequency is changed from the negative
      >>> to
      >>> positive the phase relationship between the I and Q signals is reversed.
      >>>
      >>> In my initial check out of the v6 exciter I used IQ GEN to check for RF
      >>> output over the range of +/- 20 kHz from the center frequency. I found
      >>> that
      >>> a zero time correction setting resulted in 35 dB or better of sideband
      >>> suppression over the full 40 kHz tuning range.
      >>>
      >>> 73,
      >>> Tony KB9YIG
      >>>
      >>>
      >>>
      >>>
      >>> ----- Original Message -----
      >>> From: "Bill Dumke" <billd@...>
      >>> To: <softrock40@yahoogroups.com>
      >>> Sent: Saturday, September 23, 2006 4:48 PM
      >>> Subject: Re: [softrock40] QSE Key input?
      >>>
      >>>
      >>>
      >>>
      >>>> I have some software from George Taylor that generates the quadrature
      >>>> audio tones that that are needed. And it does work. He was good enough
      >>>> to take his soundcard test software and modify it to produce the IQ
      >>>> tones. Its called SoftCW. I sent an e-mail today asking him if he
      >>>> could modify it somewhat to allow a +/- frequency input instead of the
      >>>> musical note input he has now.
      >>>>
      >>>> Bill WB5TCO
      >>>>
      >>>> Jim Miller wrote:
      >>>>
      >>>>
      >>>>> maybe the best thing for my cw-only work is to forget the qse
      >>>>> altogether
      >>>>> and
      >>>>> use a simple non-quadrature dds vfo like a dds60 or similar. no big
      >>>>> deal
      >>>>> since the spurs are easily under the required -43dbc and the odd
      >>>>> harmonics
      >>>>> can be easily filtered.
      >>>>>
      >>>>> a single freq softrock on 30m can (almost) cover the whole band with a
      >>>>> 48Khz
      >>>>> soundcard and just zero beating the transmitter should be easily done.
      >>>>>
      >>>>> if someone comes up with something better that uses the software and
      >>>>> qse
      >>>>> approach that would be cool too.
      >>>>>
      >>>>> 73
      >>>>>
      >>>>> jim ab3cv [ what's a mike? ;-) ]
      >>>>>
      >>>>>
      >>>>>
      >>>>>
      >>>>> Yahoo! Groups Links
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      >>>> Yahoo! Groups Links
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