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Help Please KIO2 L4 Burnt Out

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VK1OO, Mike Walkington

Help Please KIO2 L4 Burnt Out

Hi,

My K2 rig control via a KIO2 stopped. I discovered that RF sub
miniature choke L4, 100 micro Henry, on the main KIO2 board was open
circuit - no evidence of excessive heat etc. L4 is in the RS232 ground
path. Shorting out L4 restored rig control. I replaced L4 with a
larger version (all that I could find locally) but rig control didn't
work. I tested the new L4 and it was open circuit, again no evidence of
excessive heat. So the question is, what would cause excessive current
through L4?

I feed the KIO2 via a USB to RS232 converter which plugs into a four
port USB hub which plugs into a lap top. This combination has worked OK
for several years.

Mike VK1OO
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Cheers
Mike
VK1OO (ex AC7MZ, VK1KCK)
K2: 2599

Guy, K2AV

Re: Help Please KIO2 L4 Burnt Out

Do you have the DB9 plug that connects to the back of the KIO2 restricted
to pins 2,3, 5 ONLY? See page 21 in the KIO2 manual. If you have hooked up
a full RS232 to the KIO2 DB9 there is no telling what has gone wrong, you
can cause all kinds of problems.

http://www.elecraft.com/manual/KIO2_man_rev_B.pdf

Also L4 connects pin 5 of the common signal ground to the ground bus in the
KIO2. If that goes through to a computer where a ground (black 12V lead)
has connected and your power supply to the K2 has a problem in the ground
(black) 12V supply wire to the K2 somewhere, and you have other devices
attached to the same power supply via common grounding, including what is
connected to the computer side of the USB cable, the ground current
attempting to flow via poor ground wire connection will attempt to find any
alternate route to the K2 any way it can. That ground fault will blow L4
in the KIO2 board.

Take a DVM and see if you can draw current between pin 5 on the cable and
the ground of the K2. If you can, you need to solve your power supply
problem.

73, Guy.

On Thu, Apr 26, 2012 at 1:47 AM, VK1OO <[hidden email]> wrote:

> Hi,
>
> My K2 rig control via a KIO2 stopped. I discovered that RF sub
> miniature choke L4, 100 micro Henry, on the main KIO2 board was open
> circuit - no evidence of excessive heat etc. L4 is in the RS232 ground
> path. Shorting out L4 restored rig control. I replaced L4 with a
> larger version (all that I could find locally) but rig control didn't
> work. I tested the new L4 and it was open circuit, again no evidence of
> excessive heat. So the question is, what would cause excessive current
> through L4?
>
> I feed the KIO2 via a USB to RS232 converter which plugs into a four
> port USB hub which plugs into a lap top. This combination has worked OK
> for several years.
>
> Mike VK1OO
> ______________________________________________________________
> 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]

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VK1OO, Mike Walkington

Re: Help Please KIO2 L4 Burnt Out

Hi Guy,

Thanks

260mA! Guess that would do it.
Exploring the power supply etc now.

Mike

On 26-Apr-12 4:41 PM, Guy Olinger K2AV wrote:

> Do you have the DB9 plug that connects to the back of the KIO2
> restricted to pins 2,3, 5 ONLY? See page 21 in the KIO2 manual. If
> you have hooked up a full RS232 to the KIO2 DB9 there is no telling
> what has gone wrong, you can cause all kinds of problems.
>
> http://www.elecraft.com/manual/KIO2_man_rev_B.pdf
>
> Also L4 connects pin 5 of the common signal ground to the ground bus
> in the KIO2. If that goes through to a computer where a ground (black
> 12V lead) has connected and your power supply to the K2 has a problem
> in the ground (black) 12V supply wire to the K2 somewhere, and you
> have other devices attached to the same power supply via common
> grounding, including what is connected to the computer side of the USB
> cable, the ground current attempting to flow via poor ground wire
> connection will attempt to find any alternate route to the K2 any way
> it can. That ground fault will blow L4 in the KIO2 board.
>
> Take a DVM and see if you can draw current between pin 5 on the cable
> and the ground of the K2. If you can, you need to solve your power
> supply problem.
>
> 73, Guy.
>
> On Thu, Apr 26, 2012 at 1:47 AM, VK1OO <[hidden email]
> <mailto:[hidden email]>> wrote:
>
> Hi,
>
> My K2 rig control via a KIO2 stopped. I discovered that RF sub
> miniature choke L4, 100 micro Henry, on the main KIO2 board was open
> circuit - no evidence of excessive heat etc. L4 is in the RS232
> ground
> path. Shorting out L4 restored rig control. I replaced L4 with a
> larger version (all that I could find locally) but rig control didn't
> work. I tested the new L4 and it was open circuit, again no
> evidence of
> excessive heat. So the question is, what would cause excessive
> current
> through L4?
>
> I feed the KIO2 via a USB to RS232 converter which plugs into a four
> port USB hub which plugs into a lap top. This combination has
> worked OK
> for several years.
>
> Mike VK1OO
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
> <mailto:[hidden email]>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

Cheers
Mike
VK1OO (ex AC7MZ, VK1KCK)
K2: 2599

Guy, K2AV

Re: Help Please KIO2 L4 Burnt Out

Yikes... That certainly would do it. Also if memory serves me right, 260
ma is a typical K2 standing current in RX mode, almost as if the negative
power supply path to/in the K2 is just plain open somewhere. You will have
to determine all the possible ground paths. Let all us curious folks know
what you actually find.

Then you will need to rearrange your station wiring so that simply is not
possible. K2 should have its own dedicated power supply with NOTHING else
on it, the same as you hear preached around here for the K3.

Good luck & 73, Guy

On Thu, Apr 26, 2012 at 2:45 AM, VK1OO <[hidden email]> wrote:

> Hi Guy,
>
> Thanks
>
> 260mA! Guess that would do it.
> Exploring the power supply etc now.
>
> Mike
>
>
> On 26-Apr-12 4:41 PM, Guy Olinger K2AV wrote:
>
> Do you have the DB9 plug that connects to the back of the KIO2 restricted
> to pins 2,3, 5 ONLY? See page 21 in the KIO2 manual. If you have hooked up
> a full RS232 to the KIO2 DB9 there is no telling what has gone wrong, you
> can cause all kinds of problems.
>
> http://www.elecraft.com/manual/KIO2_man_rev_B.pdf
>
> Also L4 connects pin 5 of the common signal ground to the ground bus in
> the KIO2. If that goes through to a computer where a ground (black 12V
> lead) has connected and your power supply to the K2 has a problem in the
> ground (black) 12V supply wire to the K2 somewhere, and you have other
> devices attached to the same power supply via common grounding, including
> what is connected to the computer side of the USB cable, the ground current
> attempting to flow via poor ground wire connection will attempt to find any
> alternate route to the K2 any way it can. That ground fault will blow L4
> in the KIO2 board.
>
> Take a DVM and see if you can draw current between pin 5 on the cable
> and the ground of the K2. If you can, you need to solve your power supply
> problem.
>
> 73, Guy.
>
> On Thu, Apr 26, 2012 at 1:47 AM, VK1OO <[hidden email]> wrote:
>
>> Hi,
>>
>> My K2 rig control via a KIO2 stopped. I discovered that RF sub
>> miniature choke L4, 100 micro Henry, on the main KIO2 board was open
>> circuit - no evidence of excessive heat etc. L4 is in the RS232 ground
>> path. Shorting out L4 restored rig control. I replaced L4 with a
>> larger version (all that I could find locally) but rig control didn't
>> work. I tested the new L4 and it was open circuit, again no evidence of
>> excessive heat. So the question is, what would cause excessive current
>> through L4?
>>
>> I feed the KIO2 via a USB to RS232 converter which plugs into a four
>> port USB hub which plugs into a lap top. This combination has worked OK
>> for several years.
>>
>> Mike VK1OO
>> ______________________________________________________________
>> 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
>>
>
>

VK1OO, Mike Walkington

Re: Help Please KIO2 L4 Burnt Out

Hi Guy,

Thought I would let you (and the reflector lurkers) know the problem is
solved, but I'm not sure how.
Not a connector issue - I did one of the mods a while back to prevent that.
I did check each of the power leads to the K2, KPA100 etc, but found no
faults. Subsequently measured the current through the L4 vias as as
0.4mA. So perhaps checking each cable scared the fault away. I inserted
a new L4 and monitored the current for a few days with no observed
issues. Put the trusty K2 back together and no problems since. So,
what's the best way to prevent a recurrence of this problem?

Mike
VK1OO

On 26-Apr-12 6:08 PM, Guy Olinger K2AV wrote:

> Yikes... That certainly would do it. Also if memory serves me
> right, 260 ma is a typical K2 standing current in RX mode, almost as
> if the negative power supply path to/in the K2 is just plain open
> somewhere. You will have to determine all the possible ground paths.
> Let all us curious folks know what you actually find.
>
> Then you will need to rearrange your station wiring so that simply is
> not possible. K2 should have its own dedicated power supply with
> NOTHING else on it, the same as you hear preached around here for the K3.
>
> Good luck & 73, Guy
>
> On Thu, Apr 26, 2012 at 2:45 AM, VK1OO <[hidden email]
> <mailto:[hidden email]>> wrote:
>
> Hi Guy,
>
> Thanks
>
> 260mA! Guess that would do it.
> Exploring the power supply etc now.
>
> Mike
>
>
> On 26-Apr-12 4:41 PM, Guy Olinger K2AV wrote:
>> Do you have the DB9 plug that connects to the back of the KIO2
>> restricted to pins 2,3, 5 ONLY? See page 21 in the KIO2 manual.
>> If you have hooked up a full RS232 to the KIO2 DB9 there is no
>> telling what has gone wrong, you can cause all kinds of problems.
>>
>> http://www.elecraft.com/manual/KIO2_man_rev_B.pdf
>>
>> Also L4 connects pin 5 of the common signal ground to the ground
>> bus in the KIO2. If that goes through to a computer where a
>> ground (black 12V lead) has connected and your power supply to
>> the K2 has a problem in the ground (black) 12V supply wire to the
>> K2 somewhere, and you have other devices attached to the same
>> power supply via common grounding, including what is connected to
>> the computer side of the USB cable, the ground current attempting
>> to flow via poor ground wire connection will attempt to find any
>> alternate route to the K2 any way it can. That ground fault will
>> blow L4 in the KIO2 board.
>>
>> Take a DVM and see if you can draw current between pin 5 on the
>> cable and the ground of the K2. If you can, you need to solve
>> your power supply problem.
>>
>> 73, Guy.
>>
>> On Thu, Apr 26, 2012 at 1:47 AM, VK1OO <[hidden email]
>> <mailto:[hidden email]>> wrote:
>>
>> Hi,
>>
>> My K2 rig control via a KIO2 stopped. I discovered that RF sub
>> miniature choke L4, 100 micro Henry, on the main KIO2 board
>> was open
>> circuit - no evidence of excessive heat etc. L4 is in the
>> RS232 ground
>> path. Shorting out L4 restored rig control. I replaced L4
>> with a
>> larger version (all that I could find locally) but rig
>> control didn't
>> work. I tested the new L4 and it was open circuit, again no
>> evidence of
>> excessive heat. So the question is, what would cause
>> excessive current
>> through L4?
>>
>> I feed the KIO2 via a USB to RS232 converter which plugs into
>> a four
>> port USB hub which plugs into a lap top. This combination
>> has worked OK
>> for several years.
>>
>> Mike VK1OO
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>> <mailto:[hidden email]>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list:
>> http://www.qsl.net/donate.html
>>
>>
>

Cheers
Mike
VK1OO (ex AC7MZ, VK1KCK)
K2: 2599

Don Wilhelm-4

Re: Help Please KIO2 L4 Burnt Out

Mike,

As Guy suggests, check the ground return between your K2 and the power
supply. Also check the ground path between the computer and the K2.
Make sure all ground paths are intact,

73,
Don W3FPR

On 5/15/2012 8:03 AM, VK1OO wrote:

> Hi Guy,
>
> Thought I would let you (and the reflector lurkers) know the problem is
> solved, but I'm not sure how.
> Not a connector issue - I did one of the mods a while back to prevent that.
> I did check each of the power leads to the K2, KPA100 etc, but found no
> faults. Subsequently measured the current through the L4 vias as as
> 0.4mA. So perhaps checking each cable scared the fault away. I inserted
> a new L4 and monitored the current for a few days with no observed
> issues. Put the trusty K2 back together and no problems since. So,
> what's the best way to prevent a recurrence of this problem?
>
> Mike
> VK1OO
>
>

Guy, K2AV

Re: Help Please KIO2 L4 Burnt Out

All you'd have to have is one ground not making contact until you pushed or
checked it. Power ground is an important issue to have exactly right all
the time. You can sometimes eliminate some possible paths with separate
power supplies for some station gear. W4TV has a list of recommendations
for that based on the Microham boxes. He's focusing on ground hum and
such, but the principle applies to your situation as well. If you
understand the why for W4TV's stuff, you will see how to prevent
recurrence of your case.

73, Guy.

On Tue, May 15, 2012 at 8:40 AM, Don Wilhelm <[hidden email]> wrote:

> Mike,
>
> As Guy suggests, check the ground return between your K2 and the power
> supply. Also check the ground path between the computer and the K2.
> Make sure all ground paths are intact,
>
> 73,
> Don W3FPR
>
> On 5/15/2012 8:03 AM, VK1OO wrote:
> > Hi Guy,
> >
> > Thought I would let you (and the reflector lurkers) know the problem is
> > solved, but I'm not sure how.
> > Not a connector issue - I did one of the mods a while back to prevent
> that.
> > I did check each of the power leads to the K2, KPA100 etc, but found no
> > faults. Subsequently measured the current through the L4 vias as as
> > 0.4mA. So perhaps checking each cable scared the fault away. I inserted
> > a new L4 and monitored the current for a few days with no observed
> > issues. Put the trusty K2 back together and no problems since. So,
> > what's the best way to prevent a recurrence of this problem?
> >
> > Mike
> > VK1OO
> >
> >
> ______________________________________________________________
> 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
>