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K3 powers off when after several minutes of 12W carrier

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john@kk9a.com

K3 powers off when after several minutes of 12W carrier

Instead of pushing the 12 watt PA this hard it would sure be nice (and
cleaner) to have the option of using the KPA3A for 10-12 watts output.

John KK9A

K7TV wrote:

I have been testing sustained power capabilities of wideband HF transformers
for feeding EFHW antennas. This involves running high power through HF
transformers back to back into a dummy load. When running 200W out of the
KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
not operating. After a few minutes the K3 totally shut down. This had
nothing to do with the transformers under test; I get the same result when
running the KPA500 at 200W directly into the dummy load. After restart the
K3 shows no sign of problem unless the 200W endurance test is run again.
Then I increased power just a little bit so that the 100W stage kicked in. I
got 300W out of the KPA500, and now the K3 keeps going without shutting
down. I can see how 12W may be a bit much for the driver stage, but if so,
shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
combo to be able to produce any power level I wanted within its range. What
I see is that when the 100W stage kicks in, the output (as seen on an analog
meter) makes a big jump so that certain power levels cannot be achieved.

Thanks,
Erik K7TV

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ke9uw

Re: K3 powers off when after several minutes of 12W carrier

How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts and the K3 cuts them off at 12 Watts.

Chuck Jack
KE9UW

Sent from my iPhone, cjack

> On Mar 28, 2018, at 7:23 PM, "[hidden email]" <[hidden email]> wrote:
>
> Instead of pushing the 12 watt PA this hard it would sure be nice (and
> cleaner) to have the option of using the KPA3A for 10-12 watts output.
>
> John KK9A
>
>
> K7TV wrote:
>
> I have been testing sustained power capabilities of wideband HF transformers
> for feeding EFHW antennas. This involves running high power through HF
> transformers back to back into a dummy load. When running 200W out of the
> KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
> not operating. After a few minutes the K3 totally shut down. This had
> nothing to do with the transformers under test; I get the same result when
> running the KPA500 at 200W directly into the dummy load. After restart the
> K3 shows no sign of problem unless the 200W endurance test is run again.
> Then I increased power just a little bit so that the 100W stage kicked in. I
> got 300W out of the KPA500, and now the K3 keeps going without shutting
> down. I can see how 12W may be a bit much for the driver stage, but if so,
> shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
> combo to be able to produce any power level I wanted within its range. What
> I see is that when the 100W stage kicks in, the output (as seen on an analog
> meter) makes a big jump so that certain power levels cannot be achieved.
>
> Thanks,
> Erik K7TV
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

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Chuck, KE9UW

Wes Stewart-2

Re: K3 powers off when after several minutes of 12W carrier

Doubt that. From what I've gathered during a lot of TX IMD testing on my
original K3 and my K3S, with several (lost count) different LPA and HPA modules,
it's a 10W amp. It's allowed to go to 12W but that's a really, really bad idea,
from an IMD standpoint. IIRC it's been asked that this be "fixed" in firmware
but it hasn't seemed to be put "on the list."

Wes N7WS

On 3/29/2018 4:50 AM, hawley, charles j jr wrote:

NS9I WI

Re: K3 powers off when after several minutes of 12W carrier

In reply to this post by ke9uw

I've blown the LPA's twice running with Ft8 at 12w, with and without
pads. They do not like 12w for extended times, period ... proceed with
caution! You can run 11w all day with no problems.

73 Dwight NS9I

On 3/29/2018 7:50 AM, hawley, charles j jr wrote:

> How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts and the K3 cuts them off at 12 Watts.
>
> Chuck Jack
> KE9UW
>
> Sent from my iPhone, cjack
>
>> On Mar 28, 2018, at 7:23 PM, "[hidden email]" <[hidden email]> wrote:
>>
>> Instead of pushing the 12 watt PA this hard it would sure be nice (and
>> cleaner) to have the option of using the KPA3A for 10-12 watts output.
>>
>> John KK9A
>>
>>
>> K7TV wrote:
>>
>> I have been testing sustained power capabilities of wideband HF transformers
>> for feeding EFHW antennas. This involves running high power through HF
>> transformers back to back into a dummy load. When running 200W out of the
>> KPA500, the K3 was indicating 12W, and I think that means the 100W PA was
>> not operating. After a few minutes the K3 totally shut down. This had
>> nothing to do with the transformers under test; I get the same result when
>> running the KPA500 at 200W directly into the dummy load. After restart the
>> K3 shows no sign of problem unless the 200W endurance test is run again.
>> Then I increased power just a little bit so that the 100W stage kicked in. I
>> got 300W out of the KPA500, and now the K3 keeps going without shutting
>> down. I can see how 12W may be a bit much for the driver stage, but if so,
>> shouldn't the 100W stage kick in sooner? Also, I expected the K3/KPA500
>> combo to be able to produce any power level I wanted within its range. What
>> I see is that when the 100W stage kicks in, the output (as seen on an analog
>> meter) makes a big jump so that certain power levels cannot be achieved.
>>
>> Thanks,
>> Erik K7TV
>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
> ______________________________________________________________
> Elecraft mailing list
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> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
>

Johan Ymerson

Re: K3 powers off when after several minutes of 12W carrier

In reply to this post by Wes Stewart-2

Yes that's my experience to. I get much better IMD at 20W than at 12 W. It
would be better if the KPA3A, if present, was used for anything above 10W.

/Johan, SM0XHJ

On Thursday, 29 March 2018 14:39:49 CEST Wes Stewart wrote:

> Doubt that. From what I've gathered during a lot of TX IMD testing on my
> original K3 and my K3S, with several (lost count) different LPA and HPA
> modules, it's a 10W amp. It's allowed to go to 12W but that's a really,
> really bad idea, from an IMD standpoint. IIRC it's been asked that this be
> "fixed" in firmware but it hasn't seemed to be put "on the list."
>
> Wes N7WS
>
> On 3/29/2018 4:50 AM, hawley, charles j jr wrote:
> > How do we know that’s pushing it? Maybe the LPA is designed for 20 Watts
> > and the K3 cuts them off at 12 Watts.
> >
> > Chuck Jack
> > KE9UW
> >
> > Sent from my iPhone, cjack
> >
> >> On Mar 28, 2018, at 7:23 PM, "[hidden email]" <[hidden email]> wrote:
> >>
> >> Instead of pushing the 12 watt PA this hard it would sure be nice (and
> >> cleaner) to have the option of using the KPA3A for 10-12 watts output.
> >>
> >> John KK9A
> >>
> >>
> >> K7TV wrote:
> >>
> >> I have been testing sustained power capabilities of wideband HF
> >> transformers for feeding EFHW antennas. This involves running high power
> >> through HF transformers back to back into a dummy load. When running
> >> 200W out of the KPA500, the K3 was indicating 12W, and I think that
> >> means the 100W PA was not operating. After a few minutes the K3 totally
> >> shut down. This had nothing to do with the transformers under test; I
> >> get the same result when running the KPA500 at 200W directly into the
> >> dummy load. After restart the K3 shows no sign of problem unless the
> >> 200W endurance test is run again. Then I increased power just a little
> >> bit so that the 100W stage kicked in. I got 300W out of the KPA500, and
> >> now the K3 keeps going without shutting down. I can see how 12W may be a
> >> bit much for the driver stage, but if so, shouldn't the 100W stage kick
> >> in sooner? Also, I expected the K3/KPA500 combo to be able to produce
> >> any power level I wanted within its range. What I see is that when the
> >> 100W stage kicks in, the output (as seen on an analog meter) makes a big
> >> jump so that certain power levels cannot be achieved.
> >>
> >> Thanks,
> >> Erik K7TV
>
> ______________________________________________________________
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> 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
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