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KPA1500 in the IARU Contest Last Weekend

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KPA1500 in the IARU Contest Last Weekend

Hi

I was a member of the UK HQ team for this 24hour IARU event last weekend and
was one of the two Ops on 40M SSB.

We took it in turns to be the Run station every 4 hours and I was using a
40M 2-El yagi at 60ft. I noticed that every 30-60mins, I needed to do a
re-tune on the KPA1500 to keep the SWR at or near to 1.1:1, as it seemed to
gradually creep up over time. The amp temp peaked at 70C but was mostly at
about 55C. The SWR never got above 1.5:1 using KPA1500 screen but I know
that the yagi was really presenting about 1.6:1 at the run frequency. When
not operating as the Run station the other Op was in Partner mode spotting
mults & helping with call identification.

We were using the WinTest logging program as this enables us to private
network with the other UK HQ stations (one on CW & one on SSB for each
contest band ie. a total 12 stations at any one time, plus Partners).
Because of Covid, this year we were all single Ops working from home rather
than just a few multi op stations.

My K3S & the KPA1500 worked faultlessly for the 24hours as did Wintest but I
wonder what was the cause of the SWR increasing over time & needing a
re-tune?

73 Ray G3XLG

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Nr4c

Re: KPA1500 in the IARU Contest Last Weekend

My first thought is “Heat”!

Sent from my iPhone
...nr4c. bill

> On Jul 15, 2020, at 4:43 AM, Ray Spreadbury via Elecraft <[hidden email]> wrote:
>
> Hi
>
> I was a member of the UK HQ team for this 24hour IARU event last weekend and
> was one of the two Ops on 40M SSB.
>
> We took it in turns to be the Run station every 4 hours and I was using a
> 40M 2-El yagi at 60ft. I noticed that every 30-60mins, I needed to do a
> re-tune on the KPA1500 to keep the SWR at or near to 1.1:1, as it seemed to
> gradually creep up over time. The amp temp peaked at 70C but was mostly at
> about 55C. The SWR never got above 1.5:1 using KPA1500 screen but I know
> that the yagi was really presenting about 1.6:1 at the run frequency. When
> not operating as the Run station the other Op was in Partner mode spotting
> mults & helping with call identification.
>
> We were using the WinTest logging program as this enables us to private
> network with the other UK HQ stations (one on CW & one on SSB for each
> contest band ie. a total 12 stations at any one time, plus Partners).
> Because of Covid, this year we were all single Ops working from home rather
> than just a few multi op stations.
>
> My K3S & the KPA1500 worked faultlessly for the 24hours as did Wintest but I
> wonder what was the cause of the SWR increasing over time & needing a
> re-tune?
>
> 73 Ray G3XLG
>
> ______________________________________________________________
> 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]

Jim AB3CV

Re: KPA1500 in the IARU Contest Last Weekend

Describe your antenna system.

Jim ab3cv

On Wed, Jul 15, 2020 at 11:19 AM Nr4c <[hidden email]> wrote:

> My first thought is “Heat”!
>
>
> Sent from my iPhone
> ...nr4c. bill
>
>
> > On Jul 15, 2020, at 4:43 AM, Ray Spreadbury via Elecraft <
> [hidden email]> wrote:
> >
> > Hi
> >
> > I was a member of the UK HQ team for this 24hour IARU event last weekend
> and
> > was one of the two Ops on 40M SSB.
> >
> > We took it in turns to be the Run station every 4 hours and I was using a
> > 40M 2-El yagi at 60ft. I noticed that every 30-60mins, I needed to do a
> > re-tune on the KPA1500 to keep the SWR at or near to 1.1:1, as it seemed
> to
> > gradually creep up over time. The amp temp peaked at 70C but was mostly
> at
> > about 55C. The SWR never got above 1.5:1 using KPA1500 screen but I know
> > that the yagi was really presenting about 1.6:1 at the run frequency.
> When
> > not operating as the Run station the other Op was in Partner mode
> spotting
> > mults & helping with call identification.
> >
> > We were using the WinTest logging program as this enables us to private
> > network with the other UK HQ stations (one on CW & one on SSB for each
> > contest band ie. a total 12 stations at any one time, plus Partners).
> > Because of Covid, this year we were all single Ops working from home
> rather
> > than just a few multi op stations.
> >
> > My K3S & the KPA1500 worked faultlessly for the 24hours as did Wintest
> but I
> > wonder what was the cause of the SWR increasing over time & needing a
> > re-tune?
> >
> > 73 Ray G3XLG
> >
> > ______________________________________________________________
> > 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
> 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]

donovanf

Re: KPA1500 in the IARU Contest Last Weekend

Or water...

Are you sure your coaxial cable, balun and connectors are all dry?

From your description, the last thing I'd examine is the KPA1500

Good luck!

73
Frank
W3LPL

On Wed, Jul 15, 2020 at 11:19 AM Nr4c <[hidden email]> wrote:

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Message delivered to [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]