Hot KXPA100 Amplifier

[Jim GM]

Durring the last month of the ARRL Centennial QSO Party I was behind on
points to get into the top tire. So I finally turned on the amp and started
calling CQ on 20 -10 Meters. I noticed the the amp was getting hot and
finally tripped out on high heat. cooling fan helped but not as well as I
hoped.

I also noticed that the amp ATU would start to re tune on my transmit
frequency more than I would like. I finally tracked down the issue and came
up with a solution.

RF was coming back on the RF output cable between the KX3 and KXPA100. Some
RF was also coming back on the other cables as well.

I installed some of those DX Engineering clamp on choke cores. I bundled
the inter-connecting cables and put 3 of those cores around those cables. I
separated the RF output cable from the bundle, and took one clamp on core
and wrapped one turn  close to the amp. Took care of my problem and the amp
ran as cold as a cumber in the frig.

COMMON MODE CHOKE POWER !!!  :-)

--
Jim K9TF
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[David Ahrendts]

Would second all of this fine advice. I run the KX3 + PX3 + KAT100 into an Ameritron ALS-600S. And those clamp on chokes are essential. Using them liberally, and also making sure all the control mini-cables come no where close to the high-power coax outputs or the output from the KX3. Tidy things up nicely. Keeps the RF going where it should go.

David A., KC0XT

> On Jan 31, 2015, at 10:59 AM, Jim GM <[hidden email]> wrote:
>
> Durring the last month of the ARRL Centennial QSO Party I was behind on
> points to get into the top tire. So I finally turned on the amp and started
> calling CQ on 20 -10 Meters. I noticed the the amp was getting hot and
> finally tripped out on high heat. cooling fan helped but not as well as I
> hoped.
>
> I also noticed that the amp ATU would start to re tune on my transmit
> frequency more than I would like. I finally tracked down the issue and came
> up with a solution.
>
> RF was coming back on the RF output cable between the KX3 and KXPA100. Some
> RF was also coming back on the other cables as well.
>
> I installed some of those DX Engineering clamp on choke cores. I bundled
> the inter-connecting cables and put 3 of those cores around those cables. I
> separated the RF output cable from the bundle, and took one clamp on core
> and wrapped one turn  close to the amp. Took care of my problem and the amp
> ran as cold as a cumber in the frig.
>
> COMMON MODE CHOKE POWER !!!  :-)
>
> --
> Jim K9TF
> ______________________________________________________________
> 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]

David Ahrendts   [hidden email]  




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[Michael Walker]

Common mode choking solves  a lot of problems.

I'm a believer.

Mike va3mw


On Sat, Jan 31, 2015 at 2:51 PM, David Ahrendts <[hidden email]>
wrote:

> Would second all of this fine advice. I run the KX3 + PX3 + KAT100 into an
> Ameritron ALS-600S. And those clamp on chokes are essential. Using them
> liberally, and also making sure all the control mini-cables come no where
> close to the high-power coax outputs or the output from the KX3. Tidy
> things up nicely. Keeps the RF going where it should go.
>
> David A., KC0XT
>
> > On Jan 31, 2015, at 10:59 AM, Jim GM <[hidden email]> wrote:
> >
> > Durring the last month of the ARRL Centennial QSO Party I was behind on
> > points to get into the top tire. So I finally turned on the amp and
> started
> > calling CQ on 20 -10 Meters. I noticed the the amp was getting hot and
> > finally tripped out on high heat. cooling fan helped but not as well as I
> > hoped.
> >
> > I also noticed that the amp ATU would start to re tune on my transmit
> > frequency more than I would like. I finally tracked down the issue and
> came
> > up with a solution.
> >
> > RF was coming back on the RF output cable between the KX3 and KXPA100.
> Some
> > RF was also coming back on the other cables as well.
> >
> > I installed some of those DX Engineering clamp on choke cores. I bundled
> > the inter-connecting cables and put 3 of those cores around those
> cables. I
> > separated the RF output cable from the bundle, and took one clamp on core
> > and wrapped one turn  close to the amp. Took care of my problem and the
> amp
> > ran as cold as a cumber in the frig.
> >
> > COMMON MODE CHOKE POWER !!!  :-)
> >
> > --
> > Jim K9TF
> > ______________________________________________________________
> > 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]
>
>
>
>
> David Ahrendts   [hidden email]
>
>
>
>
> ______________________________________________________________
> 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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