[Elecraft] KPA1500 in the IARU Contest Last Weekend

[Nr4c]

My first thought is “Heat”!


Sent from my iPhone
...nr4c. bill


> On Jul 15, 2020, at 4:43 AM, Ray Spreadbury via Elecraft <elecraft at mailman.qth.net> 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
> 
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