K3 High Level Digital noise

[wa9fvp]

While transmitting, my K3 developed a high level noise.  During SSB with the mic level set at 25, there's 30 watts output power.  It sounds like digital noise.  It stops when the mic level is set to zero.  There no microphone connected and I just down loaded the latest firmware but that didn't help.  It happens on all bands and while transmitting into Bird 200 watt attenuating load.  With an additional 20db of attenuation, and a total of 50 db, I checked the TX output on my spectrum analyzer. The spectrum is clean at all TX levels.  

Jack WA9FVP
Willco Electronics.

[k6dgw]

I'd suggest calling support on Mon AM.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org

On 5/30/2015 8:25 PM, wa9fvp wrote:

> While transmitting, my K3 developed a high level noise.  During SSB with the
> mic level set at 25, there's 30 watts output power.  It sounds like digital
> noise.  It stops when the mic level is set to zero.  There no microphone
> connected and I just down loaded the latest firmware but that didn't help.
> It happens on all bands and while transmitting into Bird 200 watt
> attenuating load.  With an additional 20db of attenuation, and a total of 50
> db, I checked the TX output on my spectrum analyzer. The spectrum is clean
> at all TX levels.
>
> Jack WA9FVP
> Willco Electronics.

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[Guy Olinger K2AV]

Usually this kind of thing is external to the K3, very often
mechanical. Often happens when something external is rearranged.
Remove *everything* connected to the K3 except the power and a dummy
load. Make sure the power voltage is normal. See what you get then. If
you still have noise, put an AC voltmeter across the DC power leads.
Come back with the results.

73, Guy K2AV

---------------------

While transmitting, my K3 developed a high level noise.  During SSB with the
mic level set at 25, there's 30 watts output power.  It sounds like digital
noise.  It stops when the mic level is set to zero.  There no microphone
connected and I just down loaded the latest firmware but that didn't help.
It happens on all bands and while transmitting into Bird 200 watt
attenuating load.  With an additional 20db of attenuation, and a total of 50
db, I checked the TX output on my spectrum analyzer. The spectrum is clean
at all TX levels.

Jack WA9FVP
Willco Electronics.
______________________________________________________________
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Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[wa9fvp]

The only thing connected was the bird load and the DC power.  I think the problem is in the A to D or D to A chip or are they integrated in the DSP chip? I assume that there's a mic amp in front of the A to D.  It could cause noise problems.

[wa9fvp]

It's early Sunday morning and looking on my iPad at the K3 schematics something was wrong.  It appears that there are missing pages.  I downloaded the a new copy and was able to view the DSP schematic pages.  There are separate codacs and A to D/ D to A converters.  There's also a mic amp. Later today I'll make an attempt to trouble shoot the problem.