http://elecraft.85.s1.nabble.com/Elecraft-K4-now-in-Rob-Sherwood-s-RX-performance-table-tp7669789p7669798.html
> Congrats Wayne and team on the K4 evaluation.
>
> The two other responses do somewhat beg the question about what happens to the K3s used market and pricing. Not a lot of K3s for sale unlike the trickle to flood of k3.
>
> At one point, I thought people were hanging on to their K3s waiting for a K4 upgrade which might well still be valid but I also wonder if people will simply stay with the K3s as the performance is clearly great and forgo the flexibility an SDR rig brings.
>
> Paul
> W6PNG
> www.nomadic.blog
>
>> On May 28, 2021, at 10:32 AM, Henry Pollock - K4TMC <
[hidden email]> wrote:
>>
>> I Love my K3+(new syn)!
>>
>> 73,
>> Henry - K4TMC
>> (K3 #98)
>>
>>> On Fri, May 28, 2021 at 1:22 PM BRUCE WW8II <
[hidden email]> wrote:
>>>
>>> I LOVE my K3s
>>>
>>> Bruce
>>> WW8II
>>>
>>>> On Fri, May 28, 2021 at 12:31 PM Wayne Burdick <
[hidden email]> wrote:
>>>>
>>>> Sherwood has posted his measurements of the K4D's receiver performance in
>>>> his table:
>>>>
>>>>
http://www.sherweng.com/table.html>>>>
>>>> We're quite pleased with his test results, which confirm that the K4/K4D
>>>> is near the top of its class (direct-sampling SDRs). A K4HD would provide
>>>> somewhat higher dynamic range for those stations in extreme signal
>>>> environments, but the vast majority of operators will find that the
>>> K4/K4D
>>>> more than meets their needs.
>>>>
>>>> I'd like to highlight a few important items in Rob's chart.
>>>>
>>>> First, the K4D has a high 2 and 20 kHz dynamic range value of 101 dB.
>>>> Because it's a direct-sampling radio, this figure will hold at nearly all
>>>> offsets from strong signals. Second is the block dynamic range number
>>> (128
>>>> dB), higher than almost every other "pure" SDR measured. Finally, there's
>>>> the LO noise (local oscillator; 148 to 155 dB) -- again, very favorable
>>>> compared to all competing SDRs. This is an important number correlated
>>> with
>>>> reciprocal mixing dynamic range (RMDR).
>>>>
>>>> Taken together these demonstrate that the K4D will offer excellent
>>>> performance in crowded band conditions.
>>>>
>>>> Inevitably a question will arise regarding the chart position of the K4D
>>>> relative to a couple of our other transceivers: the K3S and KX3. There's
>>> a
>>>> bit of "apples to oranges" in both comparisons.
>>>>
>>>> The K3S uses a superhet receiver architecture. The K4HD will provide a
>>>> receive setting that emulates this superhet performance when and if it's
>>>> needed. But the "pure" (direct sampling) method used by the K4 (all
>>> models)
>>>> has many advantages. One is the elimination of artifacts associated with
>>>> crystal filters. Another is that, as a pure SDR, the K4 has a far more
>>>> flexible architecture. We'll be able to provide updates to the receive
>>> and
>>>> transmit digital signal chains that cannot be added to a superhet like
>>> the
>>>> K3S or its competitors.
>>>>
>>>> The KX3 is another Elecraft radio high on Sherwood's chart. Its
>>>> performance is excellent, especially at its price point. But its numbers
>>>> relative to the K4 are somewhat misleading, as hinted at by Rob's
>>>> footnotes. The KX3 uses a quadrature downsampling architecture, which
>>>> digitally samples at baseband audio rather than at RF. This is ideal for
>>> a
>>>> radio like the KX3 that has to have very low current drain for portable
>>>> operations. The K4 uses a direct-samping architecture that requires a
>>>> higher power digital signal chain, resulting in important benefits over
>>>> quadrature downsampling including much higher and more consistent
>>> opposite
>>>> sideband image suppression and 2nd-order intermod rejection. So the two
>>> are
>>>> really designed for different applications.
>>>>
>>>> Overall, this first independent test of the K4 validates the performance
>>>> of our SDR architecture. Feel free to send us any further performance
>>>> questions.
>>>>
>>>> 73,
>>>> Wayne
>>>> N6KR
>>>>
>>>>
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