[Elecraft] [Elecraft-K4] Zero to 500Hz noise in DATA mode

email email at nr3i.org
Thu May 26 15:10:38 EDT 2022


I asked about this same thing for my KX3 and never got any interest (or 
reply). I was expecting flat from 0.01 to xxxx.0 for the K4D.  Better, 
but not zero point zero.

With input from many, maybe it will happen (for KX3, too).  Maybe CESSB 
for the KX3 ??

The roll-off is also an issue for Winlink with VARA, too.


73, steve WB3LGC


On 5/26/22 13:04, Rob Sherwood wrote:
>
> Speaking for roll-off, there is a significant audio roll off in the 
> analog output on the high end on the order of 8 dB, dependent on the 
> selected DSP bandwidth.  I would like to see this fixed, too.
>
> A picture containing text, oven, cooking, silver Description 
> automatically generated
>
> I don’t understand why there is any low-frequency roll-off in Data mode.
>
> Rob, NC0B
>
> *From:*Elecraft-K4 at groups.io [mailto:Elecraft-K4 at groups.io] *On Behalf 
> Of *Maurizio I2NOY
> *Sent:* Thursday, May 26, 2022 9:49 AM
> *To:* Elecraft-K4 at groups.io
> *Subject:* Re: [Elecraft-K4] Zero to 500Hz noise in DATA mode
>
> Dear Grant,
>
> in data mode K4 applies filtering below about 150 Hz with some ringing 
> on the cut-off frequency.
>
> I already submitted here some pictures of WSJTx waterfall of K4 and 
> Anand 7000 DLE MkII. It seems that there is not any interest from 
> anyone to flatten the audio curve in data mode on lower frequencies or 
> move the cut-off lower than 100 Hz.
>
> If you search my posts on this group, you can see them.
>
> Best 73s,
>
> Maurizio I2NOY
>
> Il 26/05/2022 15:32, Grant Saviers - KZ1W ha scritto:
>
>     I've finally got my K4 fully integrated in place of my
>     Maestro/6700. The struggle to get enough CAT controls was finally
>     resolved. The flexibility of Flex's CAT architecture was really
>     missed.
>
>     One significant RF difference immediately noted is the noise
>     (phase noise?) in the DATA spectrum display with the LO bandwidth
>     set to zero.  The 6700 had none, at least down to a few tens of
>     Hz.  The K4 noise appears bad enough that WSJT will have
>     difficulty decoding the DX and FOX stations that tend to play as
>     low as 200Hz.  Weak stations are already hard to see on the
>     display.  OTOH, the top end of the DATA chosen bandwidth (3500)
>     seems cleaner than the 6700.
>
>     Being a total newbie to the K4 is there a means to reduce the low
>     frequency noise?  Or is this a needed K4 DSP software fix?
>
>     Grant KZ1W
>
>
>
>
>
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