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KX3 Shutdown

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Barry K3NDM

KX3 Shutdown

Has anyone seen this problem and know what causes it? The last few weeks
my KX3 S/N 323 has begun to shut down unexpectedly while running CW or
SSB. The power supply is an Astron 35 Amp linear that appears to be rock
solid. I have the KXPA100 running at the same time hooked up like the
Elecraft recommendation. When it shuts down, it takes a few seconds
before I can bring it back up, and it shuts downs the amplifier also.
Cutting back the power to 75 Watts from the amp does not appear to make
any difference. I have the minimum battery voltage set in the menu to 9.
volts.

73,
Barry
K3NDM
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AC6SL

Re: KX3 Shutdown

On Tue, Oct 7, 2014 at 6:40 PM, Barry LaZar <[hidden email]> wrote:
> ... has begun to shut down unexpectedly while running CW or SSB. The
> power supply is an Astron 35 Amp linear that appears to be rock solid....

I had a similar problem with my K3. Suspecting a power supply problem,
and after reading:

http://www.repeater-builder.com/astron/astron-intro-stuff.html

I found that the RS-35M pass transistor mounting screws were slightly
loose, i.e. I could easily tighten them perhaps 1/8 turn.
After adding "split-ring" lockwashers to the pass transistor mounting
screws, the problem has not recurred.

Also, I have added fans to the backs of the heatsinks. The RS-35M no
longer gets hot, like it used to.

-John AC6SL
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Barry K3NDM

Re: KX3 Shutdown

John,
Thanks. I'll check that. I hope that is all it is as that is the
same 35 Amp supply that I use.

73,
Barry
K3NDM

On 10/7/2014 3:25 PM, John Nogatch wrote:

> On Tue, Oct 7, 2014 at 6:40 PM, Barry LaZar <[hidden email]> wrote:
>> ... has begun to shut down unexpectedly while running CW or SSB. The
>> power supply is an Astron 35 Amp linear that appears to be rock solid....
> I had a similar problem with my K3. Suspecting a power supply problem,
> and after reading:
>
> http://www.repeater-builder.com/astron/astron-intro-stuff.html
>
> I found that the RS-35M pass transistor mounting screws were slightly
> loose, i.e. I could easily tighten them perhaps 1/8 turn.
> After adding "split-ring" lockwashers to the pass transistor mounting
> screws, the problem has not recurred.
>
> Also, I have added fans to the backs of the heatsinks. The RS-35M no
> longer gets hot, like it used to.
>
> -John AC6SL
>

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Barry K3NDM

Re: KX3 Shutdown

I found the problem, I think. It was not the power supply; I checked
everything.

Here is what happened. I went into the menu on the KX3 and turned off
the amp. I tried to break the radio using CW at 10 Watts; nothing
happened. Next, I turned on the amp again and then tried to shut down
again starting at 20 Watts and every 10 Watts after that; nothing
happened. So I tried full power, 100 Watts, and still everything stayed
up, no problem.

My hypothesis is this. Over time, something became corrupted in the
software. By "resetting" the amplifier/radio connection, the software
sorted itself out. I suspect it was really a timing problem that was
created and then removed. Nothing ever happened in receive, but it
started while running in CW at 20-25 WPM. SSB wasn't a problem until a
few days ago, so it appeared to be getting worse. I was operating last
night without a problem. I, therefore, declare the problem solved.
However, if anyone with more insight into this has any information, I'd
sure like to know about it.

73,
Barry
K3NDM

On 10/7/2014 3:44 PM, Barry LaZar wrote:

> John,
> Thanks. I'll check that. I hope that is all it is as that is the
> same 35 Amp supply that I use.
>
> 73,
> Barry
> K3NDM
>
>
> On 10/7/2014 3:25 PM, John Nogatch wrote:
>> On Tue, Oct 7, 2014 at 6:40 PM, Barry LaZar <[hidden email]> wrote:
>>> ... has begun to shut down unexpectedly while running CW or SSB. The
>>> power supply is an Astron 35 Amp linear that appears to be rock
>>> solid....
>> I had a similar problem with my K3. Suspecting a power supply problem,
>> and after reading:
>>
>> http://www.repeater-builder.com/astron/astron-intro-stuff.html
>>
>> I found that the RS-35M pass transistor mounting screws were slightly
>> loose, i.e. I could easily tighten them perhaps 1/8 turn.
>> After adding "split-ring" lockwashers to the pass transistor mounting
>> screws, the problem has not recurred.
>>
>> Also, I have added fans to the backs of the heatsinks. The RS-35M no
>> longer gets hot, like it used to.
>>
>> -John AC6SL
>>
>
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