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K3 SHUTDOWN.

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Mike Reublin

K3 SHUTDOWN.

This morning while playing in the RTTY 'test, I answered a CQ by sending
my call nine times (3 bursts of 3). 100W power. The antenna is at 1.0:1
SWR.

*CLICK* and the K3 powered off. I wasn't watching it, so didn't see any
error message. Vague I know, but it's all I have. Any thoughts?

73
Mike NF4L

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David Pratt

Re: K3 SHUTDOWN.

It has happened to me a few times, Mike. What is frustrating is that
after power up, the K3 goes back to a previous setting. You then have to
try and remember what frequency you were on before the power off.

73 de David G4DMP

In a recent message, Mike <[hidden email]> writes
>This morning while playing in the RTTY 'test, I answered a CQ by sending
>my call nine times (3 bursts of 3). 100W power. The antenna is at 1.0:1
>SWR.
>
>*CLICK* and the K3 powered off. I wasn't watching it, so didn't see any
>error message. Vague I know, but it's all I have. Any thoughts?

--
+ - - - - - - - - - - - - - - - - +
| David M Pratt, Kippax, Leeds. |
| Website: http://www.g4dmp.co.uk |
+ - - - - - - - - - - - - - - - - +

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Dr. William J. Schmidt, II

Re: K3 SHUTDOWN.

In reply to this post by Mike Reublin

Yeah... Does it power on again? If not, ...

I had the same thing happen about two months ago... the power on FET blew.
Not sure why that happens... The aux 12V reversing diode was shorted too...
but I never use the aux 12V connection.

Dr. William J. Schmidt - K9HZ / J68HZ/ 8P6HK/ ZF2HZ

Owner - Operator
Big Signal Ranch
Staunton, Illinois

email: [hidden email]

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mike
Sent: Saturday, September 29, 2012 10:52 AM
To: Elecraft Reflector
Subject: [Elecraft] K3 SHUTDOWN.

This morning while playing in the RTTY 'test, I answered a CQ by sending my
call nine times (3 bursts of 3). 100W power. The antenna is at 1.0:1 SWR.

*CLICK* and the K3 powered off. I wasn't watching it, so didn't see any
error message. Vague I know, but it's all I have. Any thoughts?

73
Mike NF4L

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Dick Roth

Re: K3 SHUTDOWN.

In reply to this post by David Pratt

I noticed that you said you were running at 100W. That may be your
problem. RTTY is a 100% duty cycle mode and I believe your rig may be
overheating to the point of self-protection (shutdown).

When I run data modes, I normally reduce power to 25W. I have never had
the same problem you describe.

--
73 de Dick, ka1oz

Elecraft K3/100(K) #859
G5RV Doublet
Titan-DX Vertical

On Sat, 2012-09-29 at 17:08 +0100, David G4DMP wrote:

> It has happened to me a few times, Mike. What is frustrating is that
> after power up, the K3 goes back to a previous setting. You then have to
> try and remember what frequency you were on before the power off.
>
> 73 de David G4DMP
>
> In a recent message, Mike <[hidden email]> writes
> >This morning while playing in the RTTY 'test, I answered a CQ by sending
> >my call nine times (3 bursts of 3). 100W power. The antenna is at 1.0:1
> >SWR.
> >
> >*CLICK* and the K3 powered off. I wasn't watching it, so didn't see any
> >error message. Vague I know, but it's all I have. Any thoughts?
>

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Mike Reublin

Re: K3 SHUTDOWN.

In reply to this post by David Pratt

Thanks David.

After getting my heart back in my chest and restarting, it's been perfect.

73, Mike

On 9/29/12 12:08 PM, David G4DMP wrote:

> It has happened to me a few times, Mike. What is frustrating is that
> after power up, the K3 goes back to a previous setting. You then have to
> try and remember what frequency you were on before the power off.
>
> 73 de David G4DMP
>
> In a recent message, Mike <[hidden email]> writes
>> This morning while playing in the RTTY 'test, I answered a CQ by sending
>> my call nine times (3 bursts of 3). 100W power. The antenna is at 1.0:1
>> SWR.
>>
>> *CLICK* and the K3 powered off. I wasn't watching it, so didn't see any
>> error message. Vague I know, but it's all I have. Any thoughts?

Mike Reublin

Re: K3 SHUTDOWN.

In reply to this post by Dick Roth

Hi, Dick.

I have not seen any caveats either in the Elecraft manual, or in Fred's
book about not being able to run at 100 watts. But you could be correct.

Any comment from Wayne, Eric or Don?

73, Mike NF4L

On 9/29/12 1:19 PM, Dick Roth--KA1OZ wrote:
> I noticed that you said you were running at 100W. That may be your
> problem. RTTY is a 100% duty cycle mode and I believe your rig may be
> overheating to the point of self-protection (shutdown).
>
> When I run data modes, I normally reduce power to 25W. I have never had
> the same problem you describe.
>

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Lyle Johnson

Re: K3 SHUTDOWN.

In the end, it is a THERMAL problem.

The K3 PA heatsink+fan has a limited, finite thermal resistance to the
ambient air, as well as a limited thermal mass of its own to absorb
heat. The heat dissipated in the PA transistors has to go somewhere,
and by design and construction it goes into the heatsink. The fan uses
moving ambient air to reduce the thermal resistance of the heat sink (or
perhaps you can view this as increasing its heat capacity).

Now, if your ambient air is cold and dense, and perhaps a bit moist, it
has relatively larger heat capacity than if it is hot, thin and dry.
Put another way, you can run more power in high duty-cycle modes if your
operating environment is cool and your altitude low than you can in a
high desert.

To find out how much power you can safely run in a high duty cycle
mode,,you should run the PA (preferably into an adequate dummy load) and
monitor its temperature rise, rate of rise and final stable temperature
for various power levels and bands (since the efficiency typically
varies from band to band) while noting your ambient air temperature (and
perhaps humidity). If you do this, you'll be able to figure out the
temperature difference between the PA and the ambient air, and how it is
affected by the power you are running or wanting to run. Or if you need
an external fan, or redirect an air conditioning duct towards the radio,
or...

Then, BEFORE the contest, while your mind is still clear, you can
determine what power setting you can safely run on each band, and set up
the K3 for that power level. You can now run the contest with one more
piece of station engineering firmly in hand for a competitive edge
(either by having a bit more power, or by not having the radio shut down
when working that rare multiplier).

As a bit of encouragement to spend a little time doing this, you may be
surprised at the PA power dissipation versus power output. And you may
learn something about thermal design, resistance, and so forth.

73,

Lyle KK7P

> ...I have not seen any caveats either in the Elecraft manual, or in Fred's
> book about not being able to run at 100 watts...
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Mark n2qt

Re: K3 SHUTDOWN.

I run a 5inch sized 24V fan powered from 12 volts or so during
RTTY contests. I watch the PA temperature, but don't normally
see it going above the upper 40's no matter how hard I push it
at the 100 watt level.

The added fan blows in through the top vents as the normal fans
pull air out. With rubber feet on the fan, and a screen to keep
wires and fingers out, it works really well for me.

Mark n2qt

-----Original Message-----
From: Lyle Johnson
Sent: Saturday, September 29, 2012 4:52 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 SHUTDOWN.

In the end, it is a THERMAL problem.

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vk4tux

K3 SHUTDOWN.

In reply to this post by Lyle Johnson

The K3 can run 100w RTTY all day long without excessive PA temperatures.
Just do it with 15v and a decent power cable/PS.
Going to 110w is not recommended as the power consumption wasted rises
considerably for just the extra 10w.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Lyle Johnson
Sent: Sunday, 30 September 2012 6:53 AM
To: [hidden email]
Subject: Re: [Elecraft] K3 SHUTDOWN.

In the end, it is a THERMAL problem.

The K3 PA heatsink+fan has a limited, finite thermal resistance to the
ambient air, as well as a limited thermal mass of its own to absorb heat.
The heat dissipated in the PA transistors has to go somewhere, and by design
and construction it goes into the heatsink. The fan uses moving ambient air
to reduce the thermal resistance of the heat sink (or perhaps you can view
this as increasing its heat capacity).

Now, if your ambient air is cold and dense, and perhaps a bit moist, it has
relatively larger heat capacity than if it is hot, thin and dry.
Put another way, you can run more power in high duty-cycle modes if your
operating environment is cool and your altitude low than you can in a high
desert.

To find out how much power you can safely run in a high duty cycle mode,,you
should run the PA (preferably into an adequate dummy load) and monitor its
temperature rise, rate of rise and final stable temperature for various
power levels and bands (since the efficiency typically varies from band to
band) while noting your ambient air temperature (and perhaps humidity). If
you do this, you'll be able to figure out the temperature difference between
the PA and the ambient air, and how it is affected by the power you are
running or wanting to run. Or if you need an external fan, or redirect an
air conditioning duct towards the radio, or...

Then, BEFORE the contest, while your mind is still clear, you can determine
what power setting you can safely run on each band, and set up the K3 for
that power level. You can now run the contest with one more piece of
station engineering firmly in hand for a competitive edge (either by having
a bit more power, or by not having the radio shut down when working that
rare multiplier).

As a bit of encouragement to spend a little time doing this, you may be
surprised at the PA power dissipation versus power output. And you may learn
something about thermal design, resistance, and so forth.

73,

Lyle KK7P

> ...I have not seen any caveats either in the Elecraft manual, or in
> Fred's book about not being able to run at 100 watts...
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Mike Reublin

Re: K3 SHUTDOWN.

In reply to this post by Mike Reublin

Thanks to all who answered. The problem turned out to be too much
voltage drop. I bypassed the terminal strip between the PS and the rig
and all is well.

73, Mike NF4L

On 9/29/12 11:52 AM, Mike wrote:

> This morning while playing in the RTTY 'test, I answered a CQ by sending
> my call nine times (3 bursts of 3). 100W power. The antenna is at 1.0:1
> SWR.
>
> *CLICK* and the K3 powered off. I wasn't watching it, so didn't see any
> error message. Vague I know, but it's all I have. Any thoughts?
>
> 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
>

k6dgw

Re: K3 SHUTDOWN.

In reply to this post by Mark n2qt

I ran RTTY on my K2/100 for several years at 100W. I did the same thing
as Mark. An old computer muffin fan with a little screen over the top
velcro-ed to a small patch on the KPA100 heat sink ... right rear area,
if I remember correctly. It blew down on the heatsink, made no noise
that I could hear at 12V **, and the heatsink stayed cool to the touch @
100W while CQ'ing.

RTTY, digital modes, AM, FM, and for that matter CW when the key is
down, is a CCS application just like a broadcast transmitter. We count
on CW to have enough key-up time to reduce that average power. If you
S&P on RTTY, you shouldn't have any problems, I didn't on the K2/100,
and I don't on the K3/KPA500.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

** Computer fans sometimes behave strangely in the presence of RF.
Mine, on 15m, with the beam headed SW back over the shack, would slow
and sometimes stop while the carrier was present when I was driving an
amp to maybe 400W. And all the sprinkler valves under my 160 antenna
tried to follow 30WPM CW on 160m at about 900W. That is hard on the
plumbing. :-)

On 9/29/2012 2:27 PM, Mark n2qt wrote:
> I run a 5inch sized 24V fan powered from 12 volts or so during
> RTTY contests. I watch the PA temperature, but don't normally
> see it going above the upper 40's no matter how hard I push it
> at the 100 watt level.

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