[Elecraft] K3 is an SDR?

[Joe Subich, W4TV]

 > I'd call the K3 a hybrid SDR and the KX3 a true SDR?

No - both are hybrid SDRs if that's the term you want to apply.
The K3 is a traditional IF based superhetrodyne/SDR where the
KX3 is a "zero IF" or direct conversion SDR.  The K3 uses two
stages of IF - 8.125 MHz and 15 KHz - with SDR modulation and
demodulation at 15 KHz.  The KX3 is a direct conversion (RF to
DC) front end with SDR based I/Q modulation and demodulation.

Neither is a "pure" SDR if your definition of a "true" SDR is
"on frequency" analog to digital and digital to analog conversion.

73,

    ... Joe, W4TV


On 12/23/2012 1:34 PM, John Lawrence wrote:
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>   Don
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> As I'd expect, you did a beautiful job summarizing the difference between the K3 and KX3
> design architecture.
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> I'd call the K3 a hybrid SDR and the KX3 a true SDR?
>
> What's interesting to me comes from looking at the leap forward in component technology to make
> direct SDR from RF possible.  This is the evolution in the chip level devices it takes to gain this single step conversion
> to baseband.  Faster and more agile DSP, A/D and D/A etc ICs are at the heart of the step forward
> between the K3 and KX3.
>
> The companies producing these chips were at my fingertips back in the days 10 to 20 years ago. Then they were only able
> to make it to lower frequency IF stages with costly designs only found in the top high tech applications such as those found in government surveillance.
>
> Back then Burr Brown, Analog Devices, Texas Instruments, Motorola, Lucent/Bell Labs were working hard with competitive designs.  Semiconductor foundry geometries were heading for half micron on 4" or 6" silicon back then.
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> The software development tools allowing greater coding efficiencies is another area that has played a major roll to bring us to this point.
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> And, his was all done within our free enterprise environment by private/public capitalized US businesses.
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> Happy Holidays
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> John, W1QS
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> Waldoboro, Maine
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