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Upper limits of KPA500?

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NK7Z

Upper limits of KPA500?

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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Re: Upper limits of KPA500?

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 <[hidden email]> 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
> ______________________________________________________________
> 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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NK7Z

Re: Upper limits of KPA500?

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 <[hidden email]> 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
>> ______________________________________________________________
>> 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]
>

Ted Edwards W3TB

Re: Upper limits of KPA500?

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 <[hidden email]> 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 <[hidden email]> 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
> >> ______________________________________________________________
> >> 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]
>

--
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."
______________________________________________________________
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NK7Z

Re: Upper limits of KPA500?

I hope others chime in with the operating temps they routinely see...
This is a very useful discussion.

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 3:47 PM, Ted Edwards W3TB wrote:

> 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 <[hidden email]
> <mailto:[hidden email]>> 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 <[hidden email]
> <mailto:[hidden email]>> 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
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:[hidden email]
> <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] <mailto:[hidden email]>
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email] <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] <mailto:[hidden email]>
>
> --
> 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."

Chuck Chandler

Re: Upper limits of KPA500?

Normally high 50's to low 60's in a rag chew. During a CW contest running
stations, it sits around 65C more or less.

On Sun, May 3, 2020 at 5:53 PM Dave Cole <[hidden email]> wrote:

> I hope others chime in with the operating temps they routinely see...
> This is a very useful discussion.
>
> 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 3:47 PM, Ted Edwards W3TB wrote:
> > 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 <[hidden email]
> > <mailto:[hidden email]>> 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 <[hidden email]
> > <mailto:[hidden email]>> 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
> > >> ______________________________________________________________
> > >> Elecraft mailing list
> > >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > >> Help: http://mailman.qth.net/mmfaq.htm
> > >> Post: mailto:[hidden email]
> > <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] <mailto:
> [hidden email]>
> > >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email] <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] <mailto:[hidden email]>
> >
> > --
> > 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."
> ______________________________________________________________
> 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]

--
73 de Chuck, WS1L

[hidden email]
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Re: Upper limits of KPA500?

In reply to this post by NK7Z

Let me state things a bit better this time. The amplifier is designed to protect itself, and does a very good job of it no matter the condition.
It will do a good job of warning you before anything bad happens; make sure bad things don’t happen very much and your amp will have a very happy life.
For temperature, it will declare a fault when the measured temperature reaches 90C. Below that the amplifier works very well, adjusting the fan to keep the PAs as cool as possible. Even though a fault is declared at 90C, the cooling system will continue to run (with the amp in STBY) to get the KPA back into its safe zone.

By the way, the KPA exhausts air because that was what our analysis and testing showed was the best for this configuration. Plenty of room behind the amp
keeps the back pressure down and the air flowing smoothly so the cooling system does its great job.

And, I agree. It is interesting to hear how others experience their KPA500s over various conditions.

73!
Jack, W6FB

> On May 3, 2020, at 3:51 PM, Dave Cole <[hidden email]> wrote:
>
> I hope others chime in with the operating temps they routinely see... This is a very useful discussion.
>
> 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 3:47 PM, Ted Edwards W3TB wrote:
>> 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 <[hidden email] <mailto:[hidden email]>> 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 <[hidden email]
>> <mailto:[hidden email]>> 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
>> >> ______________________________________________________________
>> >> Elecraft mailing list
>> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> >> Help: http://mailman.qth.net/mmfaq.htm
>> >> Post: mailto:[hidden email]
>> <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] <mailto:[hidden email]>
>> >
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email] <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] <mailto:[hidden email]>
>> --
>> 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."
> ______________________________________________________________
> 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]

ANDY DURBIN

Upper limits of KPA500?

In reply to this post by NK7Z

"It is interesting to hear how others experience their KPA500s over various conditions."

I have over a years's worth of KPA500 data recorded but it takes some effort to run it through the Excel templates to make pretty plots.

My KPA500 temperatures are strongly influenced by ambient temperature. Shack temperature is often over 30 deg C in the summer months and it's not at all unusual for my fan to run at level 3 in FT8 QSO. I think I have only reached fan speed 5 twice and that was while running temperature tests not while operating. I terminated those tests at fan speed 5 and didn't wish to push it any higher.

So many people seem to think reducing the output power will keep the temperature down. It does not. Half power is about the worst heat dissipation condition for the KPA500.

73,
Andy, k3wyc
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Rick Bates, NK7I

Re: Upper limits of KPA500?

I spent 15 minutes active on 20M FT8 this afternoon (some lurking).

At 530 watts output (on the display and utility) into a 1.13:1 antenna
load (SteppIR) for a ten minute calling period (Mongolia then Oman), the
temp rose to 66C; a few moments of elevated fan quickly brought that
down to the low 60's between transmissions.

Ambient room temp 77F. (Both calls succeeded.)

Rick NK7I
North Idaho

On 5/3/2020 7:42 PM, Andy Durbin wrote:

> "It is interesting to hear how others experience their KPA500s over various conditions."
>
> I have over a years's worth of KPA500 data recorded but it takes some effort to run it through the Excel templates to make pretty plots.
>
> My KPA500 temperatures are strongly influenced by ambient temperature. Shack temperature is often over 30 deg C in the summer months and it's not at all unusual for my fan to run at level 3 in FT8 QSO. I think I have only reached fan speed 5 twice and that was while running temperature tests not while operating. I terminated those tests at fan speed 5 and didn't wish to push it any higher.
>
> So many people seem to think reducing the output power will keep the temperature down. It does not. Half power is about the worst heat dissipation condition for the KPA500.
>
> 73,
> Andy, k3wyc
> ______________________________________________________________
> 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]

Macy monkeys

Re: Upper limits of KPA500?

In reply to this post by ANDY DURBIN

I think reaching fan speed Level 5 requires clearance for take off :)

FWIW, Wayne answered my CQ on 40 CW today with his K4. Of course, it sounded terrific. I want one!! I wonder if I can convince the XYL to contribute her economic stimulus check to the cause? Hmmm...

John K7FD

> On May 3, 2020, at 7:42 PM, Andy Durbin <[hidden email]> wrote:
>
> "It is interesting to hear how others experience their KPA500s over various conditions."
>
> I have over a years's worth of KPA500 data recorded but it takes some effort to run it through the Excel templates to make pretty plots.
>
> My KPA500 temperatures are strongly influenced by ambient temperature. Shack temperature is often over 30 deg C in the summer months and it's not at all unusual for my fan to run at level 3 in FT8 QSO. I think I have only reached fan speed 5 twice and that was while running temperature tests not while operating. I terminated those tests at fan speed 5 and didn't wish to push it any higher.
>
> So many people seem to think reducing the output power will keep the temperature down. It does not. Half power is about the worst heat dissipation condition for the KPA500.
>
> 73,
> Andy, k3wyc
> ______________________________________________________________
> 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]

kc8wh.mh

Re: Upper limits of KPA500?

In reply to this post by NK7Z

I use my KPA 500 in SSB and CW ops. Much of it as net control on traffic nets and passing traffic. A little pile up breaking during DXing and some hunt and pounce contesting.Temps usually hover around 50c with some trips to mid to upper 50s.I don't remember seeing it hit 60c.In almost four years of daily use.Mike. KC8WHSent from my Verizon, Samsung Galaxy Tablet
-------- Original message --------From: Dave Cole <[hidden email]> Date: 5/3/20 6:51 PM (GMT-05:00) To: [hidden email] Subject: Re: [Elecraft] Upper limits of KPA500? I hope others chime in with the operating temps they routinely see... This is a very useful discussion.73, and thanks,Dave (NK7Z)https://www.nk7z.netARRL Volunteer ExaminerARRL Technical SpecialistARRL Asst. Director, NW Division, Technical ResourcesOn 5/3/20 3:47 PM, Ted Edwards W3TB wrote:> 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 <[hidden email] > <mailto:[hidden email]>> 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 <[hidden email]> <mailto:[hidden email]>> 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> >> ______________________________________________________________> >> Elecraft mailing list> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft> >> Help: http://mailman.qth.net/mmfaq.htm> >> Post: mailto:[hidden email]> <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] <mailto:[hidden email]>> >> ______________________________________________________________> Elecraft mailing list> Home: http://mailman.qth.net/mailman/listinfo/elecraft> Help: http://mailman.qth.net/mmfaq.htm> Post: mailto:[hidden email] <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] <mailto:[hidden email]>> > -- > 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."______________________________________________________________Elecraft mailing listHome: http://mailman.qth.net/mailman/listinfo/elecraftHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:[hidden email] list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.htmlMessage delivered to [hidden email]
______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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NK7Z

Re: Upper limits of KPA500?

In reply to this post by Rick Bates, NK7I

Hi Rick,
That is how mine behaves as well, almost exactly like that... However,
I will be running SSTV, and that is hard on the amp... I need to do a
bit more testing prior to that.

As someone else said upthread, half power is really tough on the amp...

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 7:52 PM, Rick Bates, NK7I wrote:

> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>
> At 530 watts output (on the display and utility) into a 1.13:1 antenna
> load (SteppIR) for a ten minute calling period (Mongolia then Oman), the
> temp rose to 66C; a few moments of elevated fan quickly brought that
> down to the low 60's between transmissions.
>
> Ambient room temp 77F. (Both calls succeeded.)
>
> Rick NK7I
> North Idaho
>
> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>> "It is interesting to hear how others experience their KPA500s over
>> various conditions."
>>
>> I have over a years's worth of KPA500 data recorded but it takes some
>> effort to run it through the Excel templates to make pretty plots.
>>
>> My KPA500 temperatures are strongly influenced by ambient
>> temperature. Shack temperature is often over 30 deg C in the summer
>> months and it's not at all unusual for my fan to run at level 3 in FT8
>> QSO. I think I have only reached fan speed 5 twice and that was while
>> running temperature tests not while operating. I terminated those
>> tests at fan speed 5 and didn't wish to push it any higher.
>>
>> So many people seem to think reducing the output power will keep the
>> temperature down. It does not. Half power is about the worst heat
>> dissipation condition for the KPA500.
>>
>> 73,
>> Andy, k3wyc
>> ______________________________________________________________
>> 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]

Rick Bates, NK7I

Re: Upper limits of KPA500?

I didn't add the obvious, FT8 in that manner is a 50% duty cycle but
with enough time to 'catch the breath'.

I remember back when it first came out, Wayne suggested to 'run it with
all the LEDs lit' or something along that line but... it's capable of
MUCH more than 500 watts and wisely better limited by firmware upgrades
(in the early days I watched it put out almost 700, at which point I was
far more cautious). It's nice to know there is a certain amount of
'overhead'.

Rick NK7I

On 5/3/2020 8:23 PM, Dave Cole wrote:

> Hi Rick,
> That is how mine behaves as well, almost exactly like that... However,
> I will be running SSTV, and that is hard on the amp... I need to do a
> bit more testing prior to that.
>
> As someone else said upthread, half power is really tough on the amp...
>
> 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 7:52 PM, Rick Bates, NK7I wrote:
>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>
>> At 530 watts output (on the display and utility) into a 1.13:1
>> antenna load (SteppIR) for a ten minute calling period (Mongolia then
>> Oman), the temp rose to 66C; a few moments of elevated fan quickly
>> brought that down to the low 60's between transmissions.
>>
>> Ambient room temp 77F. (Both calls succeeded.)
>>
>> Rick NK7I
>> North Idaho
>>
>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>> "It is interesting to hear how others experience their KPA500s over
>>> various conditions."
>>>
>>> I have over a years's worth of KPA500 data recorded but it takes
>>> some effort to run it through the Excel templates to make pretty plots.
>>>
>>> My KPA500 temperatures are strongly influenced by ambient
>>> temperature. Shack temperature is often over 30 deg C in the summer
>>> months and it's not at all unusual for my fan to run at level 3 in
>>> FT8 QSO. I think I have only reached fan speed 5 twice and that was
>>> while running temperature tests not while operating. I terminated
>>> those tests at fan speed 5 and didn't wish to push it any higher.
>>>
>>> So many people seem to think reducing the output power will keep the
>>> temperature down. It does not. Half power is about the worst heat
>>> dissipation condition for the KPA500.
>>>
>>> 73,
>>> Andy, k3wyc
>>> ______________________________________________________________
>>> 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]
> ______________________________________________________________
> 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]

NK7Z

Re: Upper limits of KPA500?

Hi Rick,

This brings up a point I have been unsure about for years... Duty
Cycle... What constitutes 100%? Over how long a time frame?

If I run JT65, (one minute on one minute off), and I use a timeframe of
say 5 minutes, I buy it is 50% duty cycle.

But if I use a timeframe of one minute it is 100% Duty Cycle...

So when stating duty cycle it is important to spec the timeframe, as you
did... Is there an actual timeframe stated someplace as a standard?

I do like the way you stated it by the way... With time to 'catch the
breath'...

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 8:53 PM, Rick Bates, NK7I wrote:

> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but
> with enough time to 'catch the breath'.
>
> I remember back when it first came out, Wayne suggested to 'run it with
> all the LEDs lit' or something along that line but... it's capable of
> MUCH more than 500 watts and wisely better limited by firmware upgrades
> (in the early days I watched it put out almost 700, at which point I was
> far more cautious). It's nice to know there is a certain amount of
> 'overhead'.
>
> Rick NK7I
>
>
> On 5/3/2020 8:23 PM, Dave Cole wrote:
>> Hi Rick,
>> That is how mine behaves as well, almost exactly like that... However,
>> I will be running SSTV, and that is hard on the amp... I need to do a
>> bit more testing prior to that.
>>
>> As someone else said upthread, half power is really tough on the amp...
>>
>> 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 7:52 PM, Rick Bates, NK7I wrote:
>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>>
>>> At 530 watts output (on the display and utility) into a 1.13:1
>>> antenna load (SteppIR) for a ten minute calling period (Mongolia then
>>> Oman), the temp rose to 66C; a few moments of elevated fan quickly
>>> brought that down to the low 60's between transmissions.
>>>
>>> Ambient room temp 77F. (Both calls succeeded.)
>>>
>>> Rick NK7I
>>> North Idaho
>>>
>>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>>> "It is interesting to hear how others experience their KPA500s over
>>>> various conditions."
>>>>
>>>> I have over a years's worth of KPA500 data recorded but it takes
>>>> some effort to run it through the Excel templates to make pretty plots.
>>>>
>>>> My KPA500 temperatures are strongly influenced by ambient
>>>> temperature. Shack temperature is often over 30 deg C in the summer
>>>> months and it's not at all unusual for my fan to run at level 3 in
>>>> FT8 QSO. I think I have only reached fan speed 5 twice and that was
>>>> while running temperature tests not while operating. I terminated
>>>> those tests at fan speed 5 and didn't wish to push it any higher.
>>>>
>>>> So many people seem to think reducing the output power will keep the
>>>> temperature down. It does not. Half power is about the worst heat
>>>> dissipation condition for the KPA500.
>>>>
>>>> 73,
>>>> Andy, k3wyc
>>>> ______________________________________________________________
>>>> 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]
>> ______________________________________________________________
>> 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]

John Simmons

Re: Upper limits of KPA500?

Nowadays manufacturers use 'ICAS'. One even specs their amp for '100%
duty cycle ICAS'. ICAS=Intermittent Continuous Amateur Service'.
Gobbledegook!

100% duty cycle is what Alpha used to say.... brick on the key forever.
FT8, JT65 are 50% duty cycle modes. SSB is about 33% during transmit, CW
is 50% during transmit. Duty cycle has no time limit.

-de John NI0K

Dave Cole wrote on 5/4/2020 8:39 AM:

> Hi Rick,
>
> This brings up a point I have been unsure about for years... Duty
> Cycle... What constitutes 100%? Over how long a time frame?
>
> If I run JT65, (one minute on one minute off), and I use a timeframe
> of say 5 minutes, I buy it is 50% duty cycle.
>
> But if I use a timeframe of one minute it is 100% Duty Cycle...
>
> So when stating duty cycle it is important to spec the timeframe, as
> you did... Is there an actual timeframe stated someplace as a standard?
>
> I do like the way you stated it by the way... With time to 'catch the
> breath'...
>
> 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 8:53 PM, Rick Bates, NK7I wrote:
>> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but
>> with enough time to 'catch the breath'.
>>
>> I remember back when it first came out, Wayne suggested to 'run it
>> with all the LEDs lit' or something along that line but... it's
>> capable of MUCH more than 500 watts and wisely better limited by
>> firmware upgrades (in the early days I watched it put out almost 700,
>> at which point I was far more cautious). It's nice to know there is
>> a certain amount of 'overhead'.
>>
>> Rick NK7I
>>
>>
>> On 5/3/2020 8:23 PM, Dave Cole wrote:
>>> Hi Rick,
>>> That is how mine behaves as well, almost exactly like that...
>>> However, I will be running SSTV, and that is hard on the amp... I
>>> need to do a bit more testing prior to that.
>>>
>>> As someone else said upthread, half power is really tough on the amp...
>>>
>>> 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 7:52 PM, Rick Bates, NK7I wrote:
>>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>>>
>>>> At 530 watts output (on the display and utility) into a 1.13:1
>>>> antenna load (SteppIR) for a ten minute calling period (Mongolia
>>>> then Oman), the temp rose to 66C; a few moments of elevated fan
>>>> quickly brought that down to the low 60's between transmissions.
>>>>
>>>> Ambient room temp 77F. (Both calls succeeded.)
>>>>
>>>> Rick NK7I
>>>> North Idaho
>>>>
>>>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>>>> "It is interesting to hear how others experience their KPA500s
>>>>> over various conditions."
>>>>>
>>>>> I have over a years's worth of KPA500 data recorded but it takes
>>>>> some effort to run it through the Excel templates to make pretty
>>>>> plots.
>>>>>
>>>>> My KPA500 temperatures are strongly influenced by ambient
>>>>> temperature. Shack temperature is often over 30 deg C in the
>>>>> summer months and it's not at all unusual for my fan to run at
>>>>> level 3 in FT8 QSO. I think I have only reached fan speed 5 twice
>>>>> and that was while running temperature tests not while
>>>>> operating. I terminated those tests at fan speed 5 and didn't
>>>>> wish to push it any higher.
>>>>>
>>>>> So many people seem to think reducing the output power will keep
>>>>> the temperature down. It does not. Half power is about the
>>>>> worst heat dissipation condition for the KPA500.
>>>>>
>>>>> 73,
>>>>> Andy, k3wyc
>>>>> ______________________________________________________________
>>>>> 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]
>>> ______________________________________________________________
>>> 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]
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Message delivered to [hidden email]

NK7Z

Re: Upper limits of KPA500?

So... What is RTTY?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist
ARRL Asst. Director, NW Division, Technical Resources

On 5/4/20 6:53 AM, John Simmons wrote:

> Nowadays manufacturers use 'ICAS'. One even specs their amp for '100%
> duty cycle ICAS'. ICAS=Intermittent Continuous Amateur Service'.
> Gobbledegook!
>
> 100% duty cycle is what Alpha used to say.... brick on the key forever.
> FT8, JT65 are 50% duty cycle modes. SSB is about 33% during transmit, CW
> is 50% during transmit. Duty cycle has no time limit.
>
> -de John NI0K
>
> Dave Cole wrote on 5/4/2020 8:39 AM:
>> Hi Rick,
>>
>> This brings up a point I have been unsure about for years... Duty
>> Cycle... What constitutes 100%? Over how long a time frame?
>>
>> If I run JT65, (one minute on one minute off), and I use a timeframe
>> of say 5 minutes, I buy it is 50% duty cycle.
>>
>> But if I use a timeframe of one minute it is 100% Duty Cycle...
>>
>> So when stating duty cycle it is important to spec the timeframe, as
>> you did... Is there an actual timeframe stated someplace as a standard?
>>
>> I do like the way you stated it by the way... With time to 'catch the
>> breath'...
>>
>> 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 8:53 PM, Rick Bates, NK7I wrote:
>>> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but
>>> with enough time to 'catch the breath'.
>>>
>>> I remember back when it first came out, Wayne suggested to 'run it
>>> with all the LEDs lit' or something along that line but... it's
>>> capable of MUCH more than 500 watts and wisely better limited by
>>> firmware upgrades (in the early days I watched it put out almost 700,
>>> at which point I was far more cautious). It's nice to know there is
>>> a certain amount of 'overhead'.
>>>
>>> Rick NK7I
>>>
>>>
>>> On 5/3/2020 8:23 PM, Dave Cole wrote:
>>>> Hi Rick,
>>>> That is how mine behaves as well, almost exactly like that...
>>>> However, I will be running SSTV, and that is hard on the amp... I
>>>> need to do a bit more testing prior to that.
>>>>
>>>> As someone else said upthread, half power is really tough on the amp...
>>>>
>>>> 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 7:52 PM, Rick Bates, NK7I wrote:
>>>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>>>>
>>>>> At 530 watts output (on the display and utility) into a 1.13:1
>>>>> antenna load (SteppIR) for a ten minute calling period (Mongolia
>>>>> then Oman), the temp rose to 66C; a few moments of elevated fan
>>>>> quickly brought that down to the low 60's between transmissions.
>>>>>
>>>>> Ambient room temp 77F. (Both calls succeeded.)
>>>>>
>>>>> Rick NK7I
>>>>> North Idaho
>>>>>
>>>>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>>>>> "It is interesting to hear how others experience their KPA500s
>>>>>> over various conditions."
>>>>>>
>>>>>> I have over a years's worth of KPA500 data recorded but it takes
>>>>>> some effort to run it through the Excel templates to make pretty
>>>>>> plots.
>>>>>>
>>>>>> My KPA500 temperatures are strongly influenced by ambient
>>>>>> temperature. Shack temperature is often over 30 deg C in the
>>>>>> summer months and it's not at all unusual for my fan to run at
>>>>>> level 3 in FT8 QSO. I think I have only reached fan speed 5 twice
>>>>>> and that was while running temperature tests not while
>>>>>> operating. I terminated those tests at fan speed 5 and didn't
>>>>>> wish to push it any higher.
>>>>>>
>>>>>> So many people seem to think reducing the output power will keep
>>>>>> the temperature down. It does not. Half power is about the
>>>>>> worst heat dissipation condition for the KPA500.
>>>>>>
>>>>>> 73,
>>>>>> Andy, k3wyc
>>>>>> ______________________________________________________________
>>>>>> 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]
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>>>>> Message delivered to [hidden email]
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>>>>
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>> ______________________________________________________________
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Randy Moore

Re: Upper limits of KPA500?

In reply to this post by John Simmons

ICAS means Intermittent Commercial and Amateur Service.

From the RCA Transmitting Tube Manual:

Intermittent Commercial and Amateur Service (ICAS) covers aplications in which high tube output is a more important consideration than long tube life. The term "Intermittent Commercial" in this title applies to types of services in which the operating or "on" periods do not exceed 5 minutes each, and are followed by "off" or stand-by periods of the same or greater duration. The term "Amateur Service" covers other applications where operation is of an infrequent or highly intermittent nature, as well as the use of tubes in "amateur" transmitters. ICAS ratings generally are considerably higher than CCS ratings. Although the ability of a tube to produce greater output power is usually accompanied by a reduction in tube life, the equipment designer may decide that a small tube operated at its ICAS ratings meets his requirements better than a larger tube operated within CCS ratings.

> On May 4, 2020, at 8:55 AM, John Simmons <[hidden email]> wrote:
>
> Nowadays manufacturers use 'ICAS'. One even specs their amp for '100% duty cycle ICAS'. ICAS=Intermittent Continuous Amateur Service'. Gobbledegook!
>
> 100% duty cycle is what Alpha used to say.... brick on the key forever. FT8, JT65 are 50% duty cycle modes. SSB is about 33% during transmit, CW is 50% during transmit. Duty cycle has no time limit.
>
> -de John NI0K
>
> Dave Cole wrote on 5/4/2020 8:39 AM:
>> Hi Rick,
>>
>> This brings up a point I have been unsure about for years... Duty Cycle... What constitutes 100%? Over how long a time frame?
>>
>> If I run JT65, (one minute on one minute off), and I use a timeframe of say 5 minutes, I buy it is 50% duty cycle.
>>
>> But if I use a timeframe of one minute it is 100% Duty Cycle...
>>
>> So when stating duty cycle it is important to spec the timeframe, as you did... Is there an actual timeframe stated someplace as a standard?
>>
>> I do like the way you stated it by the way... With time to 'catch the breath'...
>>
>> 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 8:53 PM, Rick Bates, NK7I wrote:
>>> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but with enough time to 'catch the breath'.
>>>
>>> I remember back when it first came out, Wayne suggested to 'run it with all the LEDs lit' or something along that line but... it's capable of MUCH more than 500 watts and wisely better limited by firmware upgrades (in the early days I watched it put out almost 700, at which point I was far more cautious). It's nice to know there is a certain amount of 'overhead'.
>>>
>>> Rick NK7I
>>>
>>>
>>> On 5/3/2020 8:23 PM, Dave Cole wrote:
>>>> Hi Rick,
>>>> That is how mine behaves as well, almost exactly like that... However, I will be running SSTV, and that is hard on the amp... I need to do a bit more testing prior to that.
>>>>
>>>> As someone else said upthread, half power is really tough on the amp...
>>>>
>>>> 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 7:52 PM, Rick Bates, NK7I wrote:
>>>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>>>>
>>>>> At 530 watts output (on the display and utility) into a 1.13:1 antenna load (SteppIR) for a ten minute calling period (Mongolia then Oman), the temp rose to 66C; a few moments of elevated fan quickly brought that down to the low 60's between transmissions.
>>>>>
>>>>> Ambient room temp 77F. (Both calls succeeded.)
>>>>>
>>>>> Rick NK7I
>>>>> North Idaho
>>>>>
>>>>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>>>>> "It is interesting to hear how others experience their KPA500s over various conditions."
>>>>>>
>>>>>> I have over a years's worth of KPA500 data recorded but it takes some effort to run it through the Excel templates to make pretty plots.
>>>>>>
>>>>>> My KPA500 temperatures are strongly influenced by ambient temperature. Shack temperature is often over 30 deg C in the summer months and it's not at all unusual for my fan to run at level 3 in FT8 QSO. I think I have only reached fan speed 5 twice and that was while running temperature tests not while operating. I terminated those tests at fan speed 5 and didn't wish to push it any higher.
>>>>>>
>>>>>> So many people seem to think reducing the output power will keep the temperature down. It does not. Half power is about the worst heat dissipation condition for the KPA500.
>>>>>>
>>>>>> 73,
>>>>>> Andy, k3wyc
>>>>>> ______________________________________________________________
>>>>>> 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]
>>>> ______________________________________________________________
>>>> 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]
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> 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
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>
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Elecraft mailing list

Re: Upper limits of KPA500?

In reply to this post by NK7Z

From the KPA500 manual, Rev E1, page 41 Specifications:
Duty Cycle at 500 Watts 10 minutes key down / 5 minutes standby

Sometimes it is very worth while to read the manual. It gives me something to do when being stuck at home for so long gets me down.

73!
Jack, W6FB

> On May 4, 2020, at 6:39 AM, Dave Cole <[hidden email]> wrote:
>
> Hi Rick,
>
> This brings up a point I have been unsure about for years... Duty Cycle... What constitutes 100%? Over how long a time frame?
>
> If I run JT65, (one minute on one minute off), and I use a timeframe of say 5 minutes, I buy it is 50% duty cycle.
>
> But if I use a timeframe of one minute it is 100% Duty Cycle...
>
> So when stating duty cycle it is important to spec the timeframe, as you did... Is there an actual timeframe stated someplace as a standard?
>
> I do like the way you stated it by the way... With time to 'catch the breath'...
>
> 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 8:53 PM, Rick Bates, NK7I wrote:
>> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but with enough time to 'catch the breath'.
>> I remember back when it first came out, Wayne suggested to 'run it with all the LEDs lit' or something along that line but... it's capable of MUCH more than 500 watts and wisely better limited by firmware upgrades (in the early days I watched it put out almost 700, at which point I was far more cautious). It's nice to know there is a certain amount of 'overhead'.
>> Rick NK7I
>> On 5/3/2020 8:23 PM, Dave Cole wrote:
>>> Hi Rick,
>>> That is how mine behaves as well, almost exactly like that... However, I will be running SSTV, and that is hard on the amp... I need to do a bit more testing prior to that.
>>>
>>> As someone else said upthread, half power is really tough on the amp...
>>>
>>> 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 7:52 PM, Rick Bates, NK7I wrote:
>>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
>>>>
>>>> At 530 watts output (on the display and utility) into a 1.13:1 antenna load (SteppIR) for a ten minute calling period (Mongolia then Oman), the temp rose to 66C; a few moments of elevated fan quickly brought that down to the low 60's between transmissions.
>>>>
>>>> Ambient room temp 77F. (Both calls succeeded.)
>>>>
>>>> Rick NK7I
>>>> North Idaho
>>>>
>>>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
>>>>> "It is interesting to hear how others experience their KPA500s over various conditions."
>>>>>
>>>>> I have over a years's worth of KPA500 data recorded but it takes some effort to run it through the Excel templates to make pretty plots.
>>>>>
>>>>> My KPA500 temperatures are strongly influenced by ambient temperature. Shack temperature is often over 30 deg C in the summer months and it's not at all unusual for my fan to run at level 3 in FT8 QSO. I think I have only reached fan speed 5 twice and that was while running temperature tests not while operating. I terminated those tests at fan speed 5 and didn't wish to push it any higher.
>>>>>
>>>>> So many people seem to think reducing the output power will keep the temperature down. It does not. Half power is about the worst heat dissipation condition for the KPA500.
>>>>>
>>>>> 73,
>>>>> Andy, k3wyc
>>>>> ______________________________________________________________
>>>>> 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]
>>> ______________________________________________________________
>>> 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]
> ______________________________________________________________
> Elecraft mailing list
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>
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> Message delivered to [hidden email]

Ted Edwards W3TB

Re: Upper limits of KPA500?

Yes did read the manual but didn’t address the temperature matter much.

On Mon, May 4, 2020 at 11:13 Jack Brindle via Elecraft <
[hidden email]> wrote:

> From the KPA500 manual, Rev E1, page 41 Specifications:
> Duty Cycle at 500 Watts 10 minutes key down / 5 minutes standby
>
> Sometimes it is very worth while to read the manual. It gives me something
> to do when being stuck at home for so long gets me down.
>
> 73!
> Jack, W6FB
>
> > On May 4, 2020, at 6:39 AM, Dave Cole <[hidden email]> wrote:
> >
> > Hi Rick,
> >
> > This brings up a point I have been unsure about for years... Duty
> Cycle... What constitutes 100%? Over how long a time frame?
> >
> > If I run JT65, (one minute on one minute off), and I use a timeframe of
> say 5 minutes, I buy it is 50% duty cycle.
> >
> > But if I use a timeframe of one minute it is 100% Duty Cycle...
> >
> > So when stating duty cycle it is important to spec the timeframe, as you
> did... Is there an actual timeframe stated someplace as a standard?
> >
> > I do like the way you stated it by the way... With time to 'catch the
> breath'...
> >
> > 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 8:53 PM, Rick Bates, NK7I wrote:
> >> I didn't add the obvious, FT8 in that manner is a 50% duty cycle but
> with enough time to 'catch the breath'.
> >> I remember back when it first came out, Wayne suggested to 'run it with
> all the LEDs lit' or something along that line but... it's capable of MUCH
> more than 500 watts and wisely better limited by firmware upgrades (in the
> early days I watched it put out almost 700, at which point I was far more
> cautious). It's nice to know there is a certain amount of 'overhead'.
> >> Rick NK7I
> >> On 5/3/2020 8:23 PM, Dave Cole wrote:
> >>> Hi Rick,
> >>> That is how mine behaves as well, almost exactly like that... However,
> I will be running SSTV, and that is hard on the amp... I need to do a bit
> more testing prior to that.
> >>>
> >>> As someone else said upthread, half power is really tough on the amp...
> >>>
> >>> 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 7:52 PM, Rick Bates, NK7I wrote:
> >>>> I spent 15 minutes active on 20M FT8 this afternoon (some lurking).
> >>>>
> >>>> At 530 watts output (on the display and utility) into a 1.13:1
> antenna load (SteppIR) for a ten minute calling period (Mongolia then
> Oman), the temp rose to 66C; a few moments of elevated fan quickly brought
> that down to the low 60's between transmissions.
> >>>>
> >>>> Ambient room temp 77F. (Both calls succeeded.)
> >>>>
> >>>> Rick NK7I
> >>>> North Idaho
> >>>>
> >>>> On 5/3/2020 7:42 PM, Andy Durbin wrote:
> >>>>> "It is interesting to hear how others experience their KPA500s over
> various conditions."
> >>>>>
> >>>>> I have over a years's worth of KPA500 data recorded but it takes
> some effort to run it through the Excel templates to make pretty plots.
> >>>>>
> >>>>> My KPA500 temperatures are strongly influenced by ambient
> temperature. Shack temperature is often over 30 deg C in the summer months
> and it's not at all unusual for my fan to run at level 3 in FT8 QSO. I
> think I have only reached fan speed 5 twice and that was while running
> temperature tests not while operating. I terminated those tests at fan
> speed 5 and didn't wish to push it any higher.
> >>>>>
> >>>>> So many people seem to think reducing the output power will keep the
> temperature down. It does not. Half power is about the worst heat
> dissipation condition for the KPA500.
> >>>>>
> >>>>> 73,
> >>>>> Andy, k3wyc
> >>>>> ______________________________________________________________
> >>>>> 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]
> >>> ______________________________________________________________
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> >>>
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> >>> Message delivered to [hidden email]
> >> ______________________________________________________________
> >> Elecraft mailing list
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>

ANDY DURBIN

Re: Upper limits of KPA500?

In reply to this post by ANDY DURBIN

When considering the upper temperature limit of a KPA500 I think it is important to know if, for the planned operating condition, the temperature limits at a value that the owner is willing to accept. In other words, does the fan produce sufficient airflow for the temperature to reach its maximum before thermal protection kicks in. If it does, what is that limiting temperature and is it acceptable?

I have not tested any higher than 70 deg C and don't have any plans to do so. I don't want to operate there because the fan noise is intolerable. If I felt the need to operate in that region I think I would duct a much larger fan/blower to the rear chassis fan opening.

Data from one of my test runs shows the front left heat sink fin was only at 47 deg C when the finals peaked at 70 deg C. The heat sink temperature continued to rise after TX stopped and peaked at 48 deg C. This suggests to me that the thermal path between the finals and the heat sink could be improved but I have no expertise in this field.

73,
Andy, k3wyc

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