[Elecraft] K4 Receive Filter question

Tue Jan 19 14:38:58 EST 2021

 I own a radio that's currently #1 on Sherwood's list. My 20 year old K2 is essentially equal at digging weak CW out of the noise (always dominated by band noise and not the noise floor of the rig) in virtually all situations I've run into. The K2 has no KSSB so I don't compare it on SSB. If I was up against a lot of really strong close-by sigs, presumably the new rig would win, but I haven't yet run into a situation with the two rigs side by side where big nearby sigs have actually caused a discernible difference.
Comparing SSB with other rigs, the new rig can beat the others on readability of weak sigs in noise, but I don't think it's due to the fundamental performance numbers in these cases but rather the DSP algorithm which makes the difference, and I don't believe this is quantified in the testing done by Sherwood or ARRL, except perhaps in subjective comments in the text of a QST review. . 

    On Tuesday, January 19, 2021, 12:13:20 PM MST, George Thornton <gthornton at thorntonmostullaw.com> wrote:  

 I have followed the Sherwood Receiver test data over the years and I know Elecraft has always been in or near the top spot.

I also would be reluctant to upgrade to a K4 if my K3 is the same or pretty close to the same in the key performance characteristics.

I wonder whether we are nearing the theoretical limit of what can be gained in receiver performance.

The difference among the top eight to ten on the Sherwood list is not likely to be practically significant.

-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of BRUCE WW8II
Sent: Tuesday, January 19, 2021 10:40 AM
To: Louandzip <louandzip at yahoo.com>
Cc: elecraft <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] K4 Receive Filter question

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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