Posted by
juergen piezo on
Dec 17, 2009; 10:45am
URL: http://elecraft.85.s1.nabble.com/Noisy-K-3-Receiver-tp4173832p4180595.html
Hi James
This has been my impression for the last 2 years when using our clubs K3's
I decided to do a comparison with several radios.
FT1000MP
TS870S
FT1000D
TS850S
TS930S
If you blind folded yourself and did not look at the S-meter and switched between the radios, the K3 was always much more noisy. I did this test on 20 meters and 40 meters. There is no doubt that the K3's correctly calibrated S-meter shows more activity. However when you dont look at the S-meter and just listen you can hear this apparent greater "noise activity"
What is interesting if there is just signs of a starting thunder storm or light QRN, the K3 seems to make the QRN sound much worst. However when the QRN is very heavy its as bad as any other radio. I did also play with AGC setting and this result was always repeatable. I thought it was the AGC doing this, however I changed the slope and it appears to be the same.
There seems to be a mid range window in the K3 that makes the radio sound much more lively. Above and below this windows thresholds it appears to be normal in every other respect.
One thing thats very obvious with the K3 is that you need to play with the receiver EQ all the time. The difference can be very stunning when you get it right.
There can be no one EQ setting that is good for weak and general purpose listening for both CW and SSB. The K3 on a flat EQ response is poor at very weak signal SSB work. However, when you adjust the EQ it seems to bring the radio back to life.
The K3 needs a default setting thats similar to most analog radios, a defined bandpass filter that needs no EQ adjustment for CW and SSB. The K3 for some reason needs a lot of highs and treble to sound decent. Even the CW note comes alive with real body like a analog radio when the EQ is set to high /treble boost. My belief is that most who say that the K3 sounds poor is for this reason. However when you boost the highs the receiver is very tiring on your ears. So you cant seem to win here
There is something strange about how the DSP and the receiver chain works. It sounds great with strong normal signals on a quiet band. I do want to try a SCAF filter or some other audio filter to see if I can improve things. I dont have hearing problems and generally i try and leave the EQ set flat. However this has proved problematic for me, especially on weak SSB and CW.
I am a casual K3 user and I dont own a K3, however I have spent enough time operating our clubs K3's which have a broad range of serial numbers many factory assembled. I would like to try and get the new DSP board to see if that changes much. Maybe it is because I am a casual K3 user that I notice all these quirks, these probably may disappear if i used a K3 every day. In the meantime I prefer any old analog contest radio at the moment.
John
--- On Wed, 12/16/09, James Sarte <
[hidden email]> wrote:
> From: James Sarte <
[hidden email]>
> Subject: Re: [Elecraft] Noisy K-3 Receiver
> To:
[hidden email]
> Date: Wednesday, December 16, 2009, 9:42 PM
> Hi Mike,
>
> I've fiddled with all of the AGC, PRE, ATT, RF, and DSP
> options on my K3,
> and still experience a relatively high noise floor - at
> least compared to an
> FT-1000 side by side.
>
> I never gave it much thought until these subject came up on
> the reflector.
>
> Cheers,
> James K2QI
>
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]]
> On Behalf Of Mike Harris
> Sent: Wednesday, December 16, 2009 12:15 PM
> To: Bill W4ZV;
[hidden email]
> Subject: Re: [Elecraft] Noisy K-3 Receiver
>
> G'day,
>
> The simple fact is that the faithful will always suggest
> that the K3
> hears more, is more sensitive or is more transparent to
> band noise
> etc etc. Also you have to fiddle with the AGC, PRE,
> ATT and RF gain
> whereas other radios just sound nicer out of the box.
> I don't have
> a problem with fiddling with AGC and equaliser parameters
> to tailor
> the receive to my liking, but to have to do it to make it
> sound
> acceptable is another thing altogether.
>
> There is an often referred to AF filter module which
> installs on the
> main DSP board and apparently cuts out a lot of unnecessary
> high
> frequency audio. Sadly though often referred to it
> just isn't being
> made available despite very positive comment from some of
> those who
> have field tested it.
>
> The KAF2 filter for the K2 made all the difference in the
> world to
> listening to SSB.
>
> Regards,
>
> Mike VP8NO
>
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