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K3 shuts off

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Mike Reublin

K3 shuts off

I was at a friends today, looking at his K3. It's in the 1000 range of
serial numbers, not a kit.

If power is set above 95-96 watts, the rig shuts down instantly when you
transmit (at least in CW and if you press the TUNE button. Didn't try it
on any other modes).

His power supply reads 14.6V, it's a 20A supply, but we didn't read it
under load. Does the K3 have the ability to display voltage and current
draw?

I downloaded and installed 3.68 firmware, but the problem was there before.

Clues and hints, please?

73, Mike NF4L

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Bob Cunnings NW8L

Re: K3 shuts off

Yes, the K3 has the ability to display voltage and current drain.

See pg. 36 of the manual, under "VFO B Alternate Displays".

Bob NW8L

On Sat, Dec 12, 2009 at 8:47 PM, Mike <[hidden email]> wrote:

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David Pratt

Re: K3 shuts off

In reply to this post by Mike Reublin

Does this happen with the K3 fed to a 50 ohm dummy load, Mike? If not,
check that the antenna impedance is not too low, as it could be if you
are using a quarter-wave end fed. See bottom on p61 of the manual (Rev
D2). My K3 closes down on 160m with a 132ft longwire.

73

David G4DMP

In a recent message, Mike <[hidden email]> wrote ...
>
>If power is set above 95-96 watts, the rig shuts down instantly when you
>transmit (at least in CW and if you press the TUNE button. Didn't try it
>on any other modes).
>
>His power supply reads 14.6V, it's a 20A supply, but we didn't read it
>under load. Does the K3 have the ability to display voltage and current
>draw?
--
David G4DMP
Leeds, England, UK
------

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Jon Kåre Hellan

Re: K3 shuts off

In reply to this post by Mike Reublin

Mike wrote:

Used to happen to me before I got a better power supply. All 20 A
supplies aren't the same. I was able to run full power on some bands,
but on the worst band, I could only run 70W.

Jon LA4RT
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Jim Wiley-2

Re: K3 shuts off

Could be the power supply. Some regulated supplies shut down completely
if the overcurrent protection trips, and they have to be completely shut
down to reset them. Clue: is anything else connected to the supply, and
if so, does it shut down t the same time as the K3? If so, then it's a
power supply problem not a K3 problem. However, if not that, then (if
the rig is connected to an antenna when this happens) it may be RF
getting back into the rig or the power supply and and affecting the
control circuits in either one.

What happens if you try the test at lower power - say 60 watts? Do you
have access to another power supply, even temporarily? If so, try that
and see what happens. Depending on the band in use, the K3 might well
exceed 20A current draw and shut down the PS. A 25A or even a 30A PS
would probably be a better choice.

- Jim, KL7CC

> Mike wrote:
>
>> I was at a friends today, looking at his K3. It's in the 1000 range of
>> serial numbers, not a kit.
>>
>> If power is set above 95-96 watts, the rig shuts down instantly when you
>> transmit (at least in CW and if you press the TUNE button. Didn't try it
>> on any other modes).
>>
>> His power supply reads 14.6V, it's a 20A supply, but we didn't read it
>> under load. Does the K3 have the ability to display voltage and current
>> draw?
>>
>> I downloaded and installed 3.68 firmware, but the problem was there before.
>>
>> Clues and hints, please?
>>
>
>

Mike Reublin

Re: K3 shuts off

In reply to this post by Mike Reublin

Thanks gents. Good tips all. I'll pass them along.

73, Mike NF4L

Mike wrote:

> I was at a friends today, looking at his K3. It's in the 1000 range of
> serial numbers, not a kit.
>
> If power is set above 95-96 watts, the rig shuts down instantly when you
> transmit (at least in CW and if you press the TUNE button. Didn't try it
> on any other modes).
>
> His power supply reads 14.6V, it's a 20A supply, but we didn't read it
> under load. Does the K3 have the ability to display voltage and current
> draw?
>
> I downloaded and installed 3.68 firmware, but the problem was there before.
>
> Clues and hints, please?
>
> 73, Mike NF4L
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

Tom Hammond-2

Re: K3 shuts off

In reply to this post by Mike Reublin

Mike:

Sounds to me as if his P/S is going into a momentary over-current protection.

When this state occurs, it is in response to a request for the P/S to provide
current in excess of that for which it was designed to supply. For instance,
if the P/S built-in over-current protection circuit is designed to provide
22A (sightly more than the rated 20A) of current) but the device connected to
it is requiring 23A of current, the over-current protection will immediately(!)
drop the output voltage from 14 V down to somewhere around 0.3-0.6 VDC and
the resulting current will go to zero (or nearly zero anyway). You can
demonstrate this on a P/S with over-current protection by intentionally
shorting the two main power cables together.. BUT DO NOT DO THIS UNLESS YOU
ARE CERTAIN YOUR P/S HAS OVER-CURRENT PROTECTION BUILT-IN. Although most
'modern' supplies DO offer this feature, some may not, and shorting the leads
on a supply which did NOT offer it, might be somewhat DISASTROUS....!!!

Anyway... if your K3 is asking for even a little bit more current than the
P/S can supply, the supply will shut down for an INSTANT... until it thinks
the overload has been removed (as when no excessive current is being drawn)
and then it'll normally immediately return to full output voltage/current
again. Of course, by that time, the K3 appears to have shut down and then
remained off (as a result of the built-in 'brown out' firmware in the K3!!!).
The 'brown-out' firmware senses when the K3 has suffered even an instantaneous
loss of power and will place the K3 into a state of suspended animation until
power is fully cycled off/on via the [POWER] button. It's a protective measure.

The solution to your friend's problem is one of two options:

1 - Purchase a heavier-duty supply which can supply 25A
(intermittently) before
it goes into over-current protection...

2 - Reduce requested power output (probably only required on certain bands
which require just a bit more drive to produce 100W output) and live
with the existing P/S.

Personally, I'd run with option #1.

Now, to being able to SEE this problem, to confirm that it exists...

The switch from normal operation to over-current protection can be so fast that
neither meters nor digital displays will not catch it. Neither will
your eyes...!
BUT if you can hang a scope across the DC output from the P/S, set it
to a very
SLOW SWEEP SPEED, so you can see a single trace run across the
screen, and THEN
put the rig into TX at 100W of requested power, IF the problem is a momentary
over-current problem, you'll see the instantaneous drop of voltage
easily on the
o-scope trace.

Good luck,

Tom Hammond N0SS

At 21:47 12/12/2009, you wrote:

>I was at a friends today, looking at his K3. It's in the 1000 range of
>serial numbers, not a kit.
>
>If power is set above 95-96 watts, the rig shuts down instantly when you
>transmit (at least in CW and if you press the TUNE button. Didn't try it
>on any other modes).
>
>His power supply reads 14.6V, it's a 20A supply, but we didn't read it
>under load. Does the K3 have the ability to display voltage and current
>draw?
>
>I downloaded and installed 3.68 firmware, but the problem was there before.
>
>Clues and hints, please?
>
>73, Mike NF4L
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

Jon Kåre Hellan

Re: K3 shuts off

In reply to this post by Jim Wiley-2

Jim Wiley wrote:
> Could be the power supply. Some regulated supplies shut down
> completely if the overcurrent protection trips, and they have to be
> completely shut down to reset them. Clue: is anything else connected
> to the supply, and if so, does it shut down t the same time as the
> K3? If so, then it's a power supply problem not a K3 problem.
> However, if not that, then (if the rig is connected to an antenna
> when this happens) it may be RF getting back into the rig or the power
> supply and and affecting the control circuits in either one.
>
In my case, it was the K3 shutting down, not the power supply. The cause
was undervoltage. But once I
got a better power supply, the problem went away. I think both were
rated 25A, but they were clearly
very different.

Jon LA4RT

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AC7AC

Re: K3 shuts off

In reply to this post by Mike Reublin

CONTENTS DELETED

The author has deleted this message.

Mike Reublin

Re: K3 shuts off

RR Ron.

73, Mike

Ron D'Eau Claire wrote:

> Make sure he's transmitting into a good dummy load for those tests.
>
> The overvoltage protection on some supplies is easily tripped by RF getting
> into it. Even if the antenna is some distance away, a voltage loop near the
> transmitter can induce plenty of RF in the mains lines or through the rig
> and supply cable.
>
> If it doesn't happen driving a good dummy load, it's time to revisit
> grounding, etc., at the rig and supply.
>
> Ron AC7AC
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Mike
> Sent: Sunday, December 13, 2009 4:45 AM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 shuts off
>
> Thanks gents. Good tips all. I'll pass them along.
>
> 73, Mike NF4L
>
> Mike wrote:
>
>> I was at a friends today, looking at his K3. It's in the 1000 range of
>> serial numbers, not a kit.
>>
>> If power is set above 95-96 watts, the rig shuts down instantly when you
>> transmit (at least in CW and if you press the TUNE button. Didn't try it
>> on any other modes).
>>
>> His power supply reads 14.6V, it's a 20A supply, but we didn't read it
>> under load. Does the K3 have the ability to display voltage and current
>> draw?
>>
>> I downloaded and installed 3.68 firmware, but the problem was there
>>
> before.
>
>> Clues and hints, please?
>>
>> 73, Mike NF4L
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>