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[K2] where there's the smell of smoke...

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John Shadle-2

[K2] where there's the smell of smoke...

I just plugged in my rig and was getting ready to operate this evening
when something horrible happened.

I have a serial to USB cable which I use for rig control (between the
KPA100 and my laptop). I notice that when I plugged it in there was a
spark (at the computer end). Probably static charge from the fact that
I operate on a carpeted floor. I didn't think any more about it.

Next, I go upstairs to get my headphones (since my speaker isn't
working) and when I come down I smell a horrible burning smell and my
rig is keying CW (even though the key is open) and I can't stop it. I
unplugged the rig and removed power, then tried again, but got the
same result.

Where do I even begin? :-(

Thanks.
-john
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John Shadle

Re: [K2] where there's the smell of smoke...

First follow-up.

When I unplugged the key from the back of the rig, the keying stops.
If I change the input to "hand" then it keys continuously (once I plug
the key back in). Again, if I remove the key, the keying stops.

Hope this helps.

Still not sure what in the world I fried. Haven't opened up the case
to check yet. Need to get to bed now. Zzzz.

On Fri, Jan 21, 2011 at 10:00 PM, John Shadle <[hidden email]> wrote:

> I just plugged in my rig and was getting ready to operate this evening
> when something horrible happened.
>
> I have a serial to USB cable which I use for rig control (between the
> KPA100 and my laptop). I notice that when I plugged it in there was a
> spark (at the computer end). Probably static charge from the fact that
> I operate on a carpeted floor. I didn't think any more about it.
>
> Next, I go upstairs to get my headphones (since my speaker isn't
> working) and when I come down I smell a horrible burning smell and my
> rig is keying CW (even though the key is open) and I can't stop it. I
> unplugged the rig and removed power, then tried again, but got the
> same result.
>
> Where do I even begin? :-(
>
> Thanks.
> -john
>

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Don Wilhelm-4

Re: [K2] where there's the smell of smoke...

John,

Maybe you are working on it too late :-) .

If the keying stops when the key is removed, I would suspect the key and
cable rather than the K2.
To see if there is a key jack problem, plug a bare 3.5mm stereo plug
into the jack.

If your plug is only partly inserted, the dash contact in the key jack
can be touching the shell - that will key the K2 with dashes momentarily
until the plug is seated.

As a side-note -- I have found several K2 owners who severely tighten
the dress nut on the key jack (and the BNC jack as well). That really
is not necessary and can damage the jack. Just tighten a little bit
beyond finger tight. The nut holds neither the rear panel nor the jack
in place, it is just there for appearance - just tight enough to keep
the nut from backing itself off is sufficient.

73,
Don W3FPR

On 1/21/2011 10:25 PM, John Shadle wrote:

> First follow-up.
>
> When I unplugged the key from the back of the rig, the keying stops.
> If I change the input to "hand" then it keys continuously (once I plug
> the key back in). Again, if I remove the key, the keying stops.
>
> Hope this helps.
>
> Still not sure what in the world I fried. Haven't opened up the case
> to check yet. Need to get to bed now. Zzzz.
>

John Shadle

Re: [K2] where there's the smell of smoke...

Hi Don,
Thanks for the response.

I received an off-list reply from another fellow who mentioned U6 on
the KPA100 being an issue--but he said that I should be using the 3
conductor cable to connect the KPA100 to the USB-to-serial adapter. To
clarify, I *am* using the adapter in the KPA100 manual (DB9 female on
one end DB9 male on the other end) to connect to the USB-to-serial
cable.

In any case, I do agree that there is an issue related to the key or
something being shorted to ground--but I don't think that keying the
rig for the less than 2 minutes it took for me to run upstairs to get
my headphones would've caused something to burn up (which is
definitely what happened).

I'm concerned about the fact that I saw a small spark when I plugged
in the USB to my laptop and what ramifications that may have for the
KPA100 unit or its circuitry related to the rig control/DB9.

The key was definitely all the way in, though, I'll check that this
afternoon during my son's nap.

Thanks!
-john

On Sat, Jan 22, 2011 at 8:28 AM, Don Wilhelm <[hidden email]> wrote:

> John,
>
> Maybe you are working on it too late :-) .
>
> If the keying stops when the key is removed, I would suspect the key and
> cable rather than the K2.
> To see if there is a key jack problem, plug a bare 3.5mm stereo plug into
> the jack.
>
> If your plug is only partly inserted, the dash contact in the key jack can
> be touching the shell - that will key the K2 with dashes momentarily until
> the plug is seated.
>
> As a side-note -- I have found several K2 owners who severely tighten the
> dress nut on the key jack (and the BNC jack as well). That really is not
> necessary and can damage the jack. Just tighten a little bit beyond finger
> tight. The nut holds neither the rear panel nor the jack in place, it is
> just there for appearance - just tight enough to keep the nut from backing
> itself off is sufficient.
>
> 73,
> Don W3FPR
>
>
> On 1/21/2011 10:25 PM, John Shadle wrote:
>>
>> First follow-up.
>>
>> When I unplugged the key from the back of the rig, the keying stops.
>> If I change the input to "hand" then it keys continuously (once I plug
>> the key back in). Again, if I remove the key, the keying stops.
>>
>> Hope this helps.
>>
>> Still not sure what in the world I fried. Haven't opened up the case
>> to check yet. Need to get to bed now. Zzzz.
>>
>

John Shadle

Re: [K2] where there's the smell of smoke...

In reply to this post by Don Wilhelm-4

Don,
How are you always right? ;-)

I checked the key and there was definitely a bad connection there.
Things *appear* to be working just fine. I just had QSOs with WV and
MI.

Still trying to figure out why I got the burning smell, though. That
is quite curious...

Any ideas on that one?

-john W4PAH
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Don Wilhelm-4

Re: [K2] where there's the smell of smoke...

John,

I get more 'right answers' the more I work on these radios, AND if I
think I MIGHT be wrong I try to keep my mouth shut :-) .

I suspect the burning smell may have come from the base K2 PA
transistors - that is the usual cause. If you are operating at only 5
watts for QRP, you may not notice if only one transistor went out.
Try 10 watts and see what happens - if that is OK, then conclude that
something just overheated but is now fine.

73,
Don W3FPR

On 1/22/2011 10:30 AM, John Shadle wrote:

> Don,
> How are you always right? ;-)
>
> I checked the key and there was definitely a bad connection there.
> Things *appear* to be working just fine. I just had QSOs with WV and
> MI.
>
> Still trying to figure out why I got the burning smell, though. That
> is quite curious...
>
> Any ideas on that one?
>
> -john W4PAH
> ______________________________________________________________
> Elecraft mailing list
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>
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