[Elecraft] Upper limits of KPA500?

[Ted Edwards W3TB]

I am glad to see these numbers and comments, because I have wondered about
the temperatures.  If running on CW in contests, it shows upper 50s and
reaches 60C.

Thanks gang!

On Sun, May 3, 2020 at 17:42 Dave Cole <dave at nk7z.net> wrote:

> Pure paranoia!  :)
>
> I tend to creep into things I consider limits, and not race to them.  I
> normally run the amp in such a way that it never exceeds 60 or at worst
> 65 C.  Seeing it hit 70 makes me nervous...
>
> So...
>
> Prior to any excursions in to the above 70C area I need to learn more,
> which is what your post just helped me do!  Thank you!!
>
> Knowing that others can run the KPA500 90C, eases my fear of amp final
> damage.
>
> I have always ran tube amps in the past, and at one point owned a very
> sensitive SS amp, which killed a few sets of finals.
>
> It turns out there were other issues at play, (design issues I think),
> but that experience made me very jumpy about SS amps.  I almost went
> back to tube amps prior to purchasing the KPA500.  After owning KPA500
> for a while now, I would never go back to tubes...  So I am being as
> careful as possible to insure I understand what I am asking the amp to
> do, before I ask it to do something it was not designed for.
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist
> ARRL Asst. Director, NW Division, Technical Resources
>
> On 5/3/20 1:36 PM, Jack Brindle wrote:
> > Dave;
> >
> > The KPA500 will protect itself above 90C, but it will work quite well at
> 70C. Why do you stop at 70C?
> >
> > 73!
> > Jack, W6FB
> >
> >
> >> On May 3, 2020, at 1:26 PM, Dave Cole <dave at nk7z.net> wrote:
> >>
> >> Hello,
> >>
> >> I just got the new MMSSTV software, and will be running a bit of SSTV.
> SSTV is 100% duty cycle.
> >>
> >> Initial testing here indicates no power level is safe...  At 150 watts
> the KPA500 reaches 70C pretty fast, in under two minutes, and 70C is my
> upper limit for testing...  At 500 watts it reaches 70C in about the same
> time...
> >>
> >> Can I assume the amp is not the most efficient thing in the world at
> 200 watts?
> >>
> >> If the KPA500 can't deal with 100% duty cycle, for two minutes, how
> does the K3 deal with 100 watts for two minutes, at 100% duty cycle?
> >>
> >> --
> >> 73, and thanks,
> >> Dave (NK7Z)
> >> https://www.nk7z.net
> >> ARRL Volunteer Examiner
> >> ARRL Technical Specialist
> >> ARRL Asst. Director, NW Division, Technical Resources
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-- 
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."