[Elecraft] K4 Receive Filter question

[David Box]

Bruce,

Below are the receiver sensitivity specs from page 42 of the recently 
updated manual


Sensitivity    (MDS)

(Typical    values;    main    or
sub    RX,    BW    =    500    Hz)

0.1-1.5    MHz*:                Preamp    OFF/1/2: -120/-130/-135        
dBm
1.5-23    MHz:                            Preamp    OFF/1/2:     
-120/-132/-137    dBm
23-54    MHz:                                Preamp    OFF/1/2:         
-120/-132/-141    dBm
*0.1-1.5    MHz    MDS    measured    at    RX    antenna inputs.    When
using    shared    RX/TX    antenna,    sensitivity decreases    
below    1.5
MHz    due    to    intentional    high-pass    response    of T-R    
switch.


de Dave K5MWR

On 1/19/2021 12:40, BRUCE WW8II wrote:
> I work in the 2 to 3 db above the noise floor CW, and 6 to 10 db above the
> noise floor on SSB now, (that is why I presently own a K3s and a P3VGA)  so
> I guess I will have to wait for the real answer. I really cannot
> believe that Elecraft did not run their own test. If and when I spend my
> cash I am not looking for the pretty blinkie colored lights and a fancy
> screen, I want performance.  My really big issue is: receiver noise floor,
> sensitivity and DSP that does not distort or degrade the incoming signal.
>   But thank all of you for your input  and I truly appreciate all the
> comments.
>
> Bruce
> WW8II
>
>
>
> On Tue, Jan 19, 2021 at 10:43 AM Louandzip via Elecraft <
> elecraft at mailman.qth.net> wrote:
>
>>   That's not a simple or easy question to answer, especially since there's
>> been no independent test of a K4, and there are many different criteria
>> that go into it.  That said,  I'll go out on a limb and say that in most
>> all practical situations on the air, it won't be. I say that because I've
>> listened to and half-assedly compared a number of very good radios and some
>> less good radios on the air. They might sound different, and take some
>> tweaking of the controls to make them sound a similar as possible, but in
>> the end I couldn't copy sigs better on one than the other. The K3 is really
>> good in the tests, and I'm confident the K4 will surpass it, but that's at
>> level that will only matter in what I consider to be exceptional
>> circumstances.
>>
>> I'll add that I'm not the radio connoisseur that some are, and what I feel
>> is largely the same, others may find hugely different. That doesn't stop me
>> from wanting the best, even if I believe it won't make a practical
>> difference in my operating.
>>
>>
>>
>>
>>      On Tuesday, January 19, 2021, 12:47:17 AM MST, BRUCE WW8II <
>> wa8hgx at gmail.com> wrote:
>>
>>   I also would appreciate a real answer to the question.  The question is
>> will the K4 or K4D be as good or better on receive than my K3s with the
>> 2.1kHz and the 200Hz filters.
>>
>> Bruce WW8II
>>
>> On Tue, Jan 19, 2021 at 12:56 AM RVZ via Elecraft <
>> elecraft at mailman.qth.net>
>> wrote:
>>
>>> I believe there are no crystal Roofing Filters in the standard K4 model.
>>> Yet the manual talks about "one set of receive filters".  Please advise
>> the
>>> type and bandwidth of these filters?  (DSP?)
>>>
>>>  From the K4 Manual:  There are three models: the basic K4, with one set
>> of
>>> receive filters and one analog-to-digital converter (ADC); the K4D, with
>> a
>>> second set of receive filters and a second ADC; and the K4HD, which adds
>> a
>>> superheterodyne front end that can be enabled as needed to provide even
>>> greater dynamic range. The superhet module uses high-performance,
>>> narrow-band crystal filters such as those used in the Elecraft K3S.
>> Thanks
>>> & 73, Dick- K9OM
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