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  • NI0Z
    NI0Z created a new forum post in SDR Talk
    I do not advocate these practices in any way and am actually posting this for your awareness given that this is also an SDR site in general and thus applicable.

    www.tomsguide.com/us/wireless-hacking-sdr,news-19308.html

    Some you might recall project Etus and the articles in the archive, Balint actually helped me get the Etus running and I still have it and it's on my TODO list this winter to revisit the Etus.

    73
    NI0z
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  • KD8TUT
    KD8TUT thanked the user ZoneAdmin in the forum post, F.Y.I. an introduction to the term "Homodyne".
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  • The 6500 review has been edited again to catch typos and errors as well as adding minor additional editorial and Post review notes at the bottom and will continue to be updated until about next Friday.
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  • ZoneAdmin
    ZoneAdmin created a new forum post in Welcome Mat
    Shared with me by N9VV, I thought I should post it here for your review and discussion if you so desire.

    SNIP
    A friend wrote to me and said:

    "The KX3 and KX2 are Homodyne SDR's, requiring mixer calibration every 6
    months to maintain carrier/IF and opposite-side-band suppression. A
    spectrum analyzer is required for this procedure."
    That reminded me of the Dan Tayloe Quadrature Sampling Detector or
    Mixer (circa: 1999). That inexpensive design became popular in so many
    of the inexpensive SDR rigs of that era (like the Softrock) and was
    commercialized in the Flex 1500, 3000, and 5000 rigs.

    The comment that a "Homodyne" designs require re-calibration is
    absolutely true. There were various work-around schemes to keep the QSD
    in phase. One of them was the famous VE3NEA "Rocky" receiver software
    that included a careful measurement and computation to keep I and Q
    signals in Phase as you changed frequencies over a narrow range:
    <URL: www.dxatlas.com/Rocky/Advanced.asp
    > (picture attached). I don't know if Elecraft recommends
    re-calibration of their KX3/KX2 or on what schedule?.
    The DDC scheme using lightning fast FPGA and the "CORDIC" algorithm were
    introduced to Ham Radio by Phil Covington N8VB in 2007. He created the
    QS1R Receiver using the LTC-2208 ADC and Cyclone-III FPGA (pix
    attached). That same architecture was Commercialized by TAPR and Apache
    to create their Transceivers. Flex followed suit and discontinued their
    QSD gear in 2012 introducing the current 6xxx lineup using DDC
    technologies.

    The DDC architecture is self-calibrating in the sense that the FPGA
    operates at nano-second (billionths of a second) speeds and employs
    mathematical operations (32bit float point) that keep the unit in
    precise alignment (I/Q balance), at all times, on all frequencies. There
    is never an "imbalance", "center spike", or "carrier suppression" issue
    in a properly designed DDC Trx.

    The greatest disadvantage to the DDC design is that it requires a
    skilled, specialized, FPGA Engineer who can "think like a state
    machine". While DSP chips in the back end of a Homodyne can usually be
    programmed by any good "C" programmer using an Arduino or small ARM CPU.
    Please do not take this as any shot at Elecraft or Elecraft bashing. I
    have always yearned for, and drooled over, the Elecraft gear. I built
    their K2 #169 in 1997 and loved it. They have outstanding CW
    performance. Various DX Certificate hunters claim it is the best
    DXpedition rig ever invented. There are tens of thousands of very happy
    customers all over the world.
    It is fun to dig out the facts and separate it from the hype that you
    hear on the air <LOL>

    thanks for reading,
    your comments please,
    73 Ken
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  • GW4AMZ
    GW4AMZ unlocked the badge Newbie
    Newbie
    Being part of a community. To unlock this badge, you need to register on this site.
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  • GW4AMZ
    GW4AMZ just registered on the site
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  • NI0Z
    NI0Z thanked the user KD8TUT in the forum post, Flex 6500 Review is complete
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  • ZoneAdmin wrote: The initial review is now published and may also be used via the below link.


    sdrzone.com/index.php?option=com_content&view=article&id=54

    Thank you... that was a very good read. Learned a great deal about that radio.

    Very much appreciate the...
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  • Folks, I think I plan to keep the site simple, as is. It seems functional and certainly less prone to security issues. Hope you enjoy!

    73
    NI0Z
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  • A Dx off the iPad and Soul headphones today EA5GPJ via the Flex, really working well.
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