[Elecraft] Possible K3 Line Input Damage

[Don Wilhelm]

Mike,

This sound to me like you have to make a trip to the remote site to see 
what is going on.  A soundcard failure may have applied DC voltage to 
the K3 and damaged it (but I have never heard of that happening).
You may have a soundcard failure of some sort and no audio is getting to 
the K3 - so go to the site with another soundcard in hand to use if 
necessary.

When testing with the new soundcard, if the Line In does not work, lower 
the computer output of the soundcard and try Mic In (change the MIC SEL 
menu).  If that gets audio to the K3 while Line In does not, then 
contact support at elecraft.com to see where you should go from that point.

73,
Don W3FPR

On 3/9/2020 7:50 PM, Michael Tope wrote:
> Recently I've made some configuration changes at my remote station that 
> should in the end improve things. In the short term, however, it has 
> caused problems when working voice. Specifically I was getting feedback 
> if I raised the line out level on the PC too far past a certain 
> threshold which seem to depend on the K3 compressor settings (in case 
> you are wondering, yes, the K3 monitor level was set to 0). Despite 
> these problems, I was able to make some 40 meter SSB contacts Sunday 
> morning during the ARRL DX Phone contest.
> 
> On Sunday afternoon, I connected to the remote with about ten minutes to 
> go in the contest and heard PY0F calling CQ on 20 meters with a very 
> loud signal. Not having touched the settings from the night before, I 
> figured I would tweak the tuning on the KAT-500 and then just call him. 
> Things did not go well. The rig broke into audio feedback and I lost 
> transmit/receive control for what seemed like a forever, but was 
> probably in reality only about 15 seconds.
> 
> After I regained control of the rig, I power cycled the rig and then 
> power cycled the computer (I can do that remotely). The K3 still works 
> fine on CW, but I can no longer operate SSB. TeamViewer indicates I am 
> getting audio to the remote site, but the radio no longer responds. I've 
> tried both VOX and manually switching to transmit. Either way, I get 
> nothing. I even tried playing a local audio source on the computer at 
> the remote site which should have gone straight into the K3. I still got 
> nothing.
> 
> IS IT POSSIBLE TO DAMAGE THE LINE INPUT OF THE K3 IF IT IS OVERDRIVEN BY 
> A SOUNDCARD LINE OUTPUT OR DOES THE K3 SOMEHOW SELF-PROTECT? IF THE 
> FORMER, WHAT PART IN THE K3 SERVES AS THE "FUSE"?
> 
> I know it is premature to assume the K3 is damaged as I haven't 
> physically been to the remote site test the rig since the incident, but 
> I wanted to understand what the worst-case scenarios might look like.
>