KXPA100 RF feedback

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KXPA100 RF feedback

Erik Tkal
Today my KXPA100 stopped working properly.  Whenever I transmit I start getting feedback, a sort of electric stuttering effect.  When the amp is bypassed this does not occur.  Also, if I transmit into a dummy load the problem does not occur, indicating that somehow the antenna RF must be affecting the amp in some way?

Nothing has changed in my shack since yesterday, and the problem occurs with both my KX3 and KX2, so it's not the radio.  Everything is fully grounded to a copper bus bar on my desk.  I performed the factory reset through the KXPA Utility with no change.

Has anyone had this happen?


  Thanks and 73,
  Erik Tkal  -  W1QED

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Re: KXPA100 RF feedback

Don Wilhelm
Erik,

Apparently something *did* change in your antenna system.  It may not be
in the shack.

Look for something that arcs over at higher power or a loose connector
or a balun that has failed.

73,
Don W3FPR

On 1/22/2017 11:36 AM, E T wrote:

> Today my KXPA100 stopped working properly.  Whenever I transmit I start getting feedback, a sort of electric stuttering effect.  When the amp is bypassed this does not occur.  Also, if I transmit into a dummy load the problem does not occur, indicating that somehow the antenna RF must be affecting the amp in some way?
>
> Nothing has changed in my shack since yesterday, and the problem occurs with both my KX3 and KX2, so it's not the radio.  Everything is fully grounded to a copper bus bar on my desk.  I performed the factory reset through the KXPA Utility with no change.
>
> Has anyone had this happen?
>
>
>   Thanks and 73,
>   Erik Tkal  -  W1QED
>
> ______________________________________________________________
> 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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Re: KXPA100 RF feedback

Bob N3MNT
In reply to this post by Erik Tkal
Thinking it is not amp in /amp out as much as it is power level causing breakdown in antenna system.  Try amp in at 15W as a test.
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Re: KXPA100 RF feedback

Erik Tkal
In reply to this post by Don Wilhelm
Not sure what it was but I seem to have inadvertently fixed it.  I took the amp out to my Jeep and hooked it up with my KX2 to my screwdriver antenna and could not reproduce the issue.  I brought it back inside and hooked it back up and it is working ok, so it must have been a loose connection or something, even though I thought I had unhooked and reconnected everything...

In the immortal words of Emily Litella, "Never mind!"  :-)

  Thanks and 73,
  Erik Tkal  -  W1QED

On Jan 22, 2017, at 12:41 PM, Don Wilhelm <[hidden email]> wrote:

Erik,

Apparently something *did* change in your antenna system.  It may not be in the shack.

Look for something that arcs over at higher power or a loose connector or a balun that has failed.

73,
Don W3FPR

On 1/22/2017 11:36 AM, E T wrote:

> Today my KXPA100 stopped working properly.  Whenever I transmit I start getting feedback, a sort of electric stuttering effect.  When the amp is bypassed this does not occur.  Also, if I transmit into a dummy load the problem does not occur, indicating that somehow the antenna RF must be affecting the amp in some way?
>
> Nothing has changed in my shack since yesterday, and the problem occurs with both my KX3 and KX2, so it's not the radio.  Everything is fully grounded to a copper bus bar on my desk.  I performed the factory reset through the KXPA Utility with no change.
>
> Has anyone had this happen?
>
>
>  Thanks and 73,
>  Erik Tkal  -  W1QED
>
> ______________________________________________________________
> 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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Re: KXPA100 RF feedback

John Lemay
Erik

Sounds like an intermittent patch lead. You need to find it, otherwise it
will come back and bite you - guaranteed to be at the worst possible moment
!

John G4ZTR


-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of E T
Sent: Sunday, January 22, 2017 18:37
To: [hidden email]
Cc: Elecraft Reflector Reflector
Subject: Re: [Elecraft] KXPA100 RF feedback

Not sure what it was but I seem to have inadvertently fixed it.  I took the
amp out to my Jeep and hooked it up with my KX2 to my screwdriver antenna
and could not reproduce the issue.  I brought it back inside and hooked it
back up and it is working ok, so it must have been a loose connection or
something, even though I thought I had unhooked and reconnected
everything...

In the immortal words of Emily Litella, "Never mind!"  :-)

  Thanks and 73,
  Erik Tkal  -  W1QED

On Jan 22, 2017, at 12:41 PM, Don Wilhelm <[hidden email]> wrote:

Erik,

Apparently something *did* change in your antenna system.  It may not be in
the shack.

Look for something that arcs over at higher power or a loose connector or a
balun that has failed.

73,
Don W3FPR

On 1/22/2017 11:36 AM, E T wrote:
> Today my KXPA100 stopped working properly.  Whenever I transmit I start
getting feedback, a sort of electric stuttering effect.  When the amp is
bypassed this does not occur.  Also, if I transmit into a dummy load the
problem does not occur, indicating that somehow the antenna RF must be
affecting the amp in some way?
>
> Nothing has changed in my shack since yesterday, and the problem occurs
with both my KX3 and KX2, so it's not the radio.  Everything is fully
grounded to a copper bus bar on my desk.  I performed the factory reset
through the KXPA Utility with no change.

>
> Has anyone had this happen?
>
>
>  Thanks and 73,
>  Erik Tkal  -  W1QED
>
> ______________________________________________________________
> 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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Please help support this email list: http://www.qsl.net/donate.html Message
delivered to [hidden email]

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Re: KXPA100 RF feedback

john@kk9a.com
In reply to this post by Erik Tkal
If you don't find it, the problem will return. I have used a station with
bad shield connections on PL259s and it intermittently caused some feedback
issues.

John KK9A

E T etksubs at gmail.com
Sun Jan 22 13:36:46 EST 2017
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Not sure what it was but I seem to have inadvertently fixed it.  I took the
amp out to my Jeep and hooked it up with my KX2 to my screwdriver antenna
and could not reproduce the issue.  I brought it back inside and hooked it
back up and it is working ok, so it must have been a loose connection or
something, even though I thought I had unhooked and reconnected
everything...

In the immortal words of Emily Litella, "Never mind!"  :-)

  Thanks and 73,
  Erik Tkal  -  W1QED

______________________________________________________________
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Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html
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