K2 w/KPA100 power resets after approximately 2 hrs of turn-on time

[wa4ywm]

I originally posted this in July and I still have the problem. The issue is as described below past the dashed line. Note that the issue happens even if I haven't been transmitting.

Don Wilhelm helped me attempt to troubleshoot the issue. We eliminated the base K2 as the source. After that, at Don's suggestion, I installed the KPA100 upgrade kit - no success. At this point we gave up.

Recently I replaced D16 & D17 on the KPA100 after reading about similar problems caused by the damaged diodes. Still no luck.

Has anyone out there had a similar issue?

73,
Jim Elmore WA4YWM

------------------------------------------------------------------------------------------
I have a K2 serial no. 4729 with the 100W amp which I have been using for
almost 10 years.

It recently developed a problem with the following 2 symptoms:

1. After operating for some time (perhaps 1-2 hours) the Tune function will
begin to display 1 W with a 1.0-1 SWR on all bands. It normally displays
22-23W with the correct SWR shown.

2. At the same time, if I attempt to transmit, the K2 will apparently begin
to draw too much current and it shuts down and re-starts. The Tune function
also shuts the K2 down at this point.

I observed the same behavior on a dummy load - to eliminate an antenna or
feedline issue.

I also left the power supply on while letting the K2 cool down to see if the supply
was the source of the problem. Apparently not since the K2 would operate for
a significant time after turning the K2 back on.

[Vic Rosenthal]

Try checking solder connections in the lowpass filter area of the kpa100, especially the toroid leads. Often bad connections produce temperature-related problems.

Vic 4X6GP/K2VCO

> On 13 Nov 2015, at 3:27 AM, wa4ywm <[hidden email]> wrote:
>
> I originally posted this in July and I still have the problem. The issue is
> as described below past the dashed line. Note that the issue happens even if
> I haven't been transmitting.
>
> Don Wilhelm helped me attempt to troubleshoot the issue. We eliminated the
> base K2 as the source. After that, at Don's suggestion, I installed the
> KPA100 upgrade kit - no success. At this point we gave up.
>
> Recently I replaced D16 & D17 on the KPA100 after reading about similar
> problems caused by the damaged diodes. Still no luck.
>
> Has anyone out there had a similar issue?
>
> 73,
> Jim Elmore WA4YWM
>
> ------------------------------------------------------------------------------------------
> I have a K2 serial no. 4729 with the 100W amp which I have been using for
> almost 10 years.
>
> It recently developed a problem with the following 2 symptoms:
>
> 1. After operating for some time (perhaps 1-2 hours) the Tune function will
> begin to display 1 W with a 1.0-1 SWR on all bands. It normally displays
> 22-23W with the correct SWR shown.
>
> 2. At the same time, if I attempt to transmit, the K2 will apparently begin
> to draw too much current and it shuts down and re-starts. The Tune function
> also shuts the K2 down at this point.
>
> I observed the same behavior on a dummy load - to eliminate an antenna or
> feedline issue.
>
> I also left the power supply on while letting the K2 cool down to see if the
> supply
> was the source of the problem. Apparently not since the K2 would operate for
> a significant time after turning the K2 back on.
>
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K2-w-KPA100-power-resets-after-approximately-2-hrs-of-turn-on-time-tp7610298.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Don Wilhelm-4]

Jim,

"the issue happens even if I haven't been transmitting"
Does that mean you can just turn it on, leave it in receive mode, and it
turns off?
If so, you have a problem with the power circuits in the base K2 or the
components that feed the base K2 from the 12 volt power in the KPA100.
First and most likely, check the crimp pins in the housing that plugs
into K3 RF board P3 (AUX 12V).  If the crimp pins are 'mashed', they
will not make good connection - get new crimp pins and insert them
properly into the housing.
If those are OK, check the red and black wires - if they have ever been
pinched between the KPA100 shield and the K2 side panel, they may have
broken wires, replace the wires (use stranded wire).
Check the soldering of KPA100 D9.
In the base K2, check the soldering of F1 and the power switch.  You
might consider replacing F1.

73,
Don W3FPR

On 11/12/2015 8:27 PM, wa4ywm wrote:
> I originally posted this in July and I still have the problem. The issue is
> as described below past the dashed line. Note that the issue happens even if
> I haven't been transmitting.
>
>

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