Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

Thank you for a very thorough, and cogent, explanation of that.

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

On 5/7/20 7:12 AM, Ignacy wrote:

NK7Z wrote


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?


Correct!

Up to a certain limit, the output power increases with PA current
quadratically. So the maximum dissipation may be below the max power, and
decreasing power does not reduce dissipation much.

Assume that at 600W KPA500 operates at 60% efficiency. 1000W total, 400W
dissipation.
Now reduced the power to 1/4 or 150W. The input current is reduced 50% to
500W. The dissipation is 350W, not much below 400W at full power. With
KAP500, the dissipation at low power can actually get worse than predicted
since the power supply is unregulated and has higher voltage at lower
current.

Reduction of dissipation at low power can be done at least 2 ways. One is
reduction of voltage as done in SPE amps. The other one is changing the the
transformation ratio of output amp, e.g., in KX3; hard to do at high power.

One can have the action of a different transformation ratio with a manual
tuner. Once my 20A power supply died but I had a 5A supply available. But
the max power was only 5W before the power supply switched off. 1/4 curent =
1/16 power. By adjusting a manual tuner for max output I got 20W. But KPA
may not let this trick go because of SWR. protection.

Ignacy, NO9E





--
Sent from: http://elecraft.365791.n2.nabble.com/
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Ignacy]

NK7Z wrote
> 
> 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?

Correct!

Up to a certain limit, the output power increases with PA current
quadratically. So the maximum dissipation may be below the max power, and
decreasing power does not reduce dissipation much.

Assume that at 600W KPA500 operates at 60% efficiency. 1000W total, 400W
dissipation.
Now reduced the power to 1/4 or 150W. The input current is reduced 50% to
500W. The dissipation is 350W, not much below 400W at full power. With
KAP500, the dissipation at low power can actually get worse than predicted
since the power supply is unregulated and has higher voltage at lower
current.

Reduction of dissipation at low power can be done at least 2 ways. One is
reduction of voltage as done in SPE amps. The other one is changing the the
transformation ratio of output amp, e.g., in KX3; hard to do at high power.

One can have the action of a different transformation ratio with a manual
tuner. Once my 20A power supply died but I had a 5A supply available. But
the max power was only 5W before the power supply switched off. 1/4 curent =
1/16 power. By adjusting a manual tuner for max output I got 20W. But KPA
may not let this trick go because of SWR. protection.   

Ignacy, NO9E





--
Sent from: http://elecraft.365791.n2.nabble.com/
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Macy monkeys]

I ragchew on CW and have my KPA500 fan set on level 2 as a default. I don't 
really keep an eye on the temp. When I hear fan level 3 kick in, that's my cue 
I've been too longed winded and time to turn it over :)

John K7FD


> On May 6, 2020, at 11:03 AM, Tom Azlin W7SUA  wrote:
> 
> Hi Dave,
> 
> I run around 100-150 watts out of my KPA500 using 5-7 watts from my K3 with 
> the KPA500 hitting 70C using Olivia during nets. I assume could go to 250 but 
> never needed that much power. Does not seem to be a problem with temps above 
> 70c. Also run up to 500w PEP using SSB when needed.
> 
> I did hear Wayne say run full power RTTY with no fear.
> 
> 73, tom w7sua
> 
> 
> 
> 
> 
>> On 5/3/2020 1:26 PM, Dave Cole 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?
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to macymonk...@charter.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Bob McGraw K4TAX]

As long as one stays within the duty cycle times limits, no problem.

Do note that some antenna system which are lower impedance will require 
the amp to draw more current for a given amount of power. And it does 
vary from band to band.    The attached EXCEL spreadsheet should be of 
interest regarding lower power operation.


73

Bob, K4TAX


On 5/6/2020 1:03 PM, Tom Azlin W7SUA wrote:

Hi Dave,

I run around 100-150 watts out of my KPA500 using 5-7 watts from my K3 
with the KPA500 hitting 70C using Olivia during nets. I assume could 
go to 250 but never needed that much power. Does not seem to be a 
problem with temps above 70c. Also run up to 500w PEP using SSB when 
needed.


I did hear Wayne say run full power RTTY with no fear.

73, tom w7sua





On 5/3/2020 1:26 PM, Dave Cole 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?



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rmcg...@blomand.net 
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Tom Azlin W7SUA]

Hi Dave,

I run around 100-150 watts out of my KPA500 using 5-7 watts from my K3 
with the KPA500 hitting 70C using Olivia during nets. I assume could go 
to 250 but never needed that much power. Does not seem to be a problem 
with temps above 70c. Also run up to 500w PEP using SSB when needed.


I did hear Wayne say run full power RTTY with no fear.

73, tom w7sua





On 5/3/2020 1:26 PM, Dave Cole 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?



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Nr4c]

Why not let the computer in the amp do its job?  And besides, the fans run 
after the amp is turned OFF. This discharges the caps and starts the orderly 
“cool down” cycle. 

You may be a brilliant engineer, but no need to re-engineer a system that works 
pretty well. 

Sent from my iPhone
...nr4c. bill


> On May 5, 2020, at 5:35 PM, Eric Norris  wrote:
> 
> This has been very educational.  I have, unfortunately, faulted both my
> veteran KPA500 and KPA1500 more times than I can count.  I've been so
> paranoid about keeping them otherwise healthy, that I manually manipulate
> the fan speed using the utilities--increasing the KPA500 fan speed when it
> gets into the 60Cs, and the KPA1500 when it gets into the 70Cs.
> 
> The downside is I sometimes forget to reduce the fans when the chase is
> over, and the amps quickly cool to room temperature, only to heat up again
> when the next chase is underfoot.  Is this rapid cooling and heating even
> worse for the life of the devices, and then again what about turning off
> the amps when going QRT?  Should they be cooled to room temp first, or just
> until the fans stop running in NOR mode?
> 
> The question isn't is one paranoid, but is one paranoid enough?
> 
> 73 Eric WD6DBM
> 
>> On Mon, May 4, 2020, 9:12 AM Jack Brindle via Elecraft <
>> elecraft@mailman.qth.net> 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
>> 
>> 
>> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to n...@widomaker.com 
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Frank Scolaro]

Actually that would be good to know...  I let the 
fans take the temp down to room temp before 
shutting the 1500 off... Frank (W2YK)


At 07:35 PM 5/5/2020, Dave Cole wrote:
Remember...  Just because you think they are out 
to get you, does not mean they are not out to 
get you... 73, and thanks, Dave (NK7Z) 
https://www.nk7z.net ARRL Volunteer Examiner 
ARRL Technical Specialist ARRL Asst. Director, 
NW Division, Technical Resources On 5/5/20 2:33 
PM, Eric Norris wrote: > This has been very 
educational.  I have, unfortunately, faulted 
both my > veteran KPA500 and KPA1500 more times 
than I can count.  I've been so > paranoid 
about keeping them otherwise healthy, that I 
manually > manipulate the fan speed using the 
utilities--increasing the KPA500 fan > speed 
when it gets into the 60Cs, and the KPA1500 when 
it gets into the > 70Cs. > > The downside is I 
sometimes forget to reduce the fans when the 
chase is > over, and the amps quickly cool to 
room temperature, only to heat up > again when 
the next chase is underfoot.  Is this rapid 
cooling and > heating even worse for the life of 
the devices, and then again what > about turning 
off the amps when going QRT?  Should they be 
cooled to > room temp first, or just until the 
fans stop running in NOR mode? > > The question 
isn't is one paranoid, but is one paranoid 
enough? > > 73 Eric WD6DBM > > On Mon, May 4, 
2020, 9:12 AM Jack Brindle via Elecraft > 
> 
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 > > 
__ 
Elecraft mailing list Home: 
http://mailman.qth.net/mailman/listinfo/elecraft 
Help: http://mailman.qth.net/mmfaq.htm Post: 
mailto:Elecraft@mailman.qth.net This list hosted 
by: http://www.qsl.net Please help support this 
email list: http://www.qsl.net/donate.html Message delivered to w...@arrl.net


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

Remember...  Just because you think they are out to get you, does not 
mean they are not out to get you...


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

On 5/5/20 2:33 PM, Eric Norris wrote:
This has been very educational.  I have, unfortunately, faulted both my 
veteran KPA500 and KPA1500 more times than I can count.  I've been so 
paranoid about keeping them otherwise healthy, that I manually 
manipulate the fan speed using the utilities--increasing the KPA500 fan 
speed when it gets into the 60Cs, and the KPA1500 when it gets into the 
70Cs.


The downside is I sometimes forget to reduce the fans when the chase is 
over, and the amps quickly cool to room temperature, only to heat up 
again when the next chase is underfoot.  Is this rapid cooling and 
heating even worse for the life of the devices, and then again what 
about turning off the amps when going QRT?  Should they be cooled to 
room temp first, or just until the fans stop running in NOR mode?


The question isn't is one paranoid, but is one paranoid enough?

73 Eric WD6DBM

On Mon, May 4, 2020, 9:12 AM Jack Brindle via Elecraft 
mailto:elecraft@mailman.qth.net>> 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



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Eric Norris]

This has been very educational.  I have, unfortunately, faulted both my
veteran KPA500 and KPA1500 more times than I can count.  I've been so
paranoid about keeping them otherwise healthy, that I manually manipulate
the fan speed using the utilities--increasing the KPA500 fan speed when it
gets into the 60Cs, and the KPA1500 when it gets into the 70Cs.

The downside is I sometimes forget to reduce the fans when the chase is
over, and the amps quickly cool to room temperature, only to heat up again
when the next chase is underfoot.  Is this rapid cooling and heating even
worse for the life of the devices, and then again what about turning off
the amps when going QRT?  Should they be cooled to room temp first, or just
until the fans stop running in NOR mode?

The question isn't is one paranoid, but is one paranoid enough?

73 Eric WD6DBM

On Mon, May 4, 2020, 9:12 AM Jack Brindle via Elecraft <
elecraft@mailman.qth.net> 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
>
>
>
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Nr4c]

I imagine like a repeater. Always ON w/light load and intermittent heavy load. 

Sent from my iPhone
...nr4c. bill


> On May 4, 2020, at 7:03 PM, John Simmons  wrote:
> 
> Bob,
> 
> My bad... thanks for the correction. However, the key word is 'intermittent'. 
> So, what in the world does 'continuous intermittent' mean?
> 
> -de John NI0K
> 
> Bob McGraw K4TAX wrote on 5/4/2020 3:06 PM:
>> That would be "Intermittent Commercial and Amateur Service".
>> 
>> 73
>> 
>> Bob, K4TAX
>> 
>> 
>> 
>>> On 5/4/2020 1:24 PM, Jim Brown wrote:
>>> On 5/4/2020 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!
>>> 
>>> 
>> 
>> __
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft@mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to jasimm...@pinewooddata.com 
> 
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to n...@widomaker.com 
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[John Simmons]

Bob,

My bad... thanks for the correction. However, the key word is 
'intermittent'. So, what in the world does 'continuous intermittent' mean?


-de John NI0K

Bob McGraw K4TAX wrote on 5/4/2020 3:06 PM:

That would be "Intermittent Commercial and Amateur Service".

73

Bob, K4TAX



On 5/4/2020 1:24 PM, Jim Brown wrote:

On 5/4/2020 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!





__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jasimm...@pinewooddata.com 


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Bob McGraw K4TAX]

That would be "Intermittent Commercial and Amateur Service".

73

Bob, K4TAX



On 5/4/2020 1:24 PM, Jim Brown wrote:

On 5/4/2020 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!





__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Edward R Cole]

That seems excessive (shows good engineering).

FM seems to be the hardest mode on amps.  If you are long-winded 
probably exceed 3-minutes which is common Time-out-timer limit on 
commercial FM gear (and several ham rigs, too).  I have a fan switch 
on my 150w 2m amp and too often forget to switch it on when operating 
FM.  My 222 FM 30w radio has built-in TOT which shuts off Tx at 
3-minutes of transmit.


On my QRO sspa's I try not to do any key-down tests over a minute in 
length (and they are designed for JT65 service).  Having overtemp 
protection and SWR protection is good insurance for protecting those 
expensive components.  All my amps have that.


Maybe someday I will own a KPA500 (do very little HF and have a 1000w 6m sspa).

73, Ed - KL7UW

I once blew up a 500w dummy load by excessive transmit time running 
1200w.  Had that old Sierra MW for about 30-years.  Now have a 
surplus 500w Bird dummy.



Date: Mon, 4 May 2020 09:11:56 -0700
From: Jack Brindle 
To: Dave Cole 
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Upper limits of KPA500?
Message-ID: <8d7f4c18-45f5-408a-b13b-e0bff47a9...@me.com>
Content-Type: text/plain;   charset=us-ascii

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


73, Ed - KL7UW
  http://www.kl7uw.com
Dubus-NA Business mail:
  dubus...@gmail.com 


__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

1850, or 1950?  Sorry Jim, I had too...  :)

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 11:24 AM, Jim Brown wrote:

Not really. ICAS and CCS have been used by power tube mfrs longer than I 
have been reading their data sheets in the '50s.


73, Jim K9YC
__

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Jim Brown]

On 5/4/2020 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!


Not really. ICAS and CCS have been used by power tube mfrs longer than I 
have been reading their data sheets in the '50s.


73, Jim K9YC
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

Thank you Jack...  I had not seen that.  That answers the question.

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 9:11 AM, Jack Brindle wrote:

 From the KPA500 manual, Rev E1, page 41 Specifications:

Duty Cycle at 500 Watts10 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 > 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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

Hi John,

Pretty much every answer to the Duty Cycle question involved time, hence 
why I asked about RTTY, that forced the issue of time to come into the 
definition.


Based on the manual definition, 10 minutes out of every 15 can be in 
transmit.  That seems to constitute 100% duty cycle for the KPA500.  So 
I now have my question answered.


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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email 

Re: [Elecraft] Upper limits of KPA500?

[Michael Walker]

Thanks Jack!

I guess part 2 to Jack's comments are...

If it gets too hot, it starts to dial back the output power.

(I would have to read the manual again to see if that is in there).

Mike va3mw


On Mon, May 4, 2020 at 12:12 PM Jack Brindle via Elecraft <
elecraft@mailman.qth.net> 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  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:Elecraft@mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to rick.n...@gmail.com
>  __
>  Elecraft mailing list
>  Home: http://mailman.qth.net/mailman/listinfo/elecraft
>  Help: http://mailman.qth.net/mmfaq.htm
>  Post: mailto:Elecraft@mailman.qth.net
> 
>  This list hosted by: http://www.qsl.net
>  Please help support this email list: http://www.qsl.net/donate.html
>  Message delivered to d...@nk7z.net
> >>> __
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>> 

Re: [Elecraft] Upper limits of KPA500?

[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






__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Ted Edwards W3TB]

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 <
elecraft@mailman.qth.net> 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  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:Elecraft@mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to rick.n...@gmail.com
>  __
>  Elecraft mailing list
>  Home: http://mailman.qth.net/mailman/listinfo/elecraft
>  Help: http://mailman.qth.net/mmfaq.htm
>  Post: mailto:Elecraft@mailman.qth.net
> 
>  This list hosted by: http://www.qsl.net
>  Please help support this email list: http://www.qsl.net/donate.html
>  Message delivered to d...@nk7z.net
> >>> __
> >>> Elecraft mailing list
> >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >>> Help: http://mailman.qth.net/mmfaq.htm
> >>> Post: mailto:Elecraft@mailman.qth.net
> >>>
> >>> This list hosted by: 

Re: [Elecraft] Upper limits of KPA500?

[Jack Brindle via Elecraft]

>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  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:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to rick.n...@gmail.com
 __
 Elecraft mailing list
 Home: http://mailman.qth.net/mailman/listinfo/elecraft
 Help: http://mailman.qth.net/mmfaq.htm
 Post: mailto:Elecraft@mailman.qth.net
 
 This list hosted by: http://www.qsl.net
 Please help support this email list: http://www.qsl.net/donate.html
 Message delivered to d...@nk7z.net
>>> __
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft@mailman.qth.net
>>> 
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to rick.n...@gmail.com 
>> __
>> Elecraft mailing list
>> Home: 

Re: [Elecraft] Upper limits of KPA500?

[Walter Underwood]

The FCC document on estimating RF exposure lists “duty factor” for various 
modes. That is average power compared to peak while transmitting.

SSB 20%
SSB with heavy speech processing 50%
FM, FSK, RTTY, carrier 100%
CW 40%

Separately, they talk about on/off periods, the average time spent transmitting 
during a 6 minute or 30 minute period. See pages 14 and 15.

https://transition.fcc.gov/bureaus/oet/info/documents/bulletins/oet65/oet65b.pdf

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On May 4, 2020, at 7:40 AM, Randy Moore  wrote:
> 
> 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  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.  
>>> 

Re: [Elecraft] Upper limits of KPA500?

[Randy Moore]

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  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

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: 

Re: [Elecraft] Upper limits of KPA500?

[John Simmons]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Rick Bates, NK7I]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to d...@nk7z.net

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[kc8wh.mh]

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  Date: 5/3/20  
6:51 PM  (GMT-05:00) To: elecraft@mailman.qth.net 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  <mailto:d...@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  
<mailto:d...@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>  
>> __>  >> 
Elecraft mailing list>  >> Home: 
http://mailman.qth.net/mailman/listinfo/elecraft>  >> Help: 
http://mailman.qth.net/mmfaq.htm>  >> Post: 
mailto:Elecraft@mailman.qth.net> <mailto:Elecraft@mailman.qth.net>>  
>>>  >> This list hosted by: http://www.qsl.net>  >> Please help 
support this email list: http://www.qsl.net/donate.html>  >> Message 
delivered to jackbrin...@me.com <mailto:jackbrin...@me.com>>  >> 
__> Elecraft 
mailing list> Home: http://mailman.qth.net/mailman/listinfo/elecraft> 
Help: http://mailman.qth.net/mmfaq.htm> Post: 
mailto:Elecraft@mailman.qth.net <mailto:Elecraft@mailman.qth.net>> > This 
list hosted by: http://www.qsl.net> Please help support this email list: 
http://www.qsl

Re: [Elecraft] Upper limits of KPA500?

[Macy monkeys]

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  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:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to macymonk...@charter.net 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Rick Bates, NK7I]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rick.n...@gmail.com

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

[Elecraft] Upper limits of KPA500?

[Andy Durbin]

"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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Jack Brindle via Elecraft]

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  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 > > 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 >> 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:Elecraft@mailman.qth.net
>>
>> >>
>> >> This list hosted by: http://www.qsl.net
>> >> Please help support this email list: http://www.qsl.net/donate.html
>> >> Message delivered to jackbrin...@me.com 
>> >
>>__
>>Elecraft mailing list
>>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>Help: http://mailman.qth.net/mmfaq.htm
>>Post: mailto:Elecraft@mailman.qth.net 
>>This list hosted by: http://www.qsl.net

Re: [Elecraft] Upper limits of KPA500?

[Chuck Chandler]

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  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  > > 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  > > 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:Elecraft@mailman.qth.net
> > 
> >  >>
> >  >> This list hosted by: http://www.qsl.net
> >  >> Please help support this email list:
> http://www.qsl.net/donate.html
> >  >> Message delivered to jackbrin...@me.com  jackbrin...@me.com>
> >  >
> > __
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft@mailman.qth.net  Elecraft@mailman.qth.net>
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to w3tb@gmail.com 
> >
> > --
> > 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:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

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 > 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 mailto:d...@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
 >> __
 >> Elecraft mailing list
 >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
 >> Help: http://mailman.qth.net/mmfaq.htm
 >> Post: mailto:Elecraft@mailman.qth.net

 >>
 >> This list hosted by: http://www.qsl.net
 >> Please help support this email list: http://www.qsl.net/donate.html
 >> Message delivered to jackbrin...@me.com 
 >
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net 

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to w3tb@gmail.com 

--
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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [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  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  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:Elecraft@mailman.qth.net
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >> Message delivered to jackbrin...@me.com
> >
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft@mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to w3tb@gmail.com
>
-- 
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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Dave Cole]

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  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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jackbrin...@me.com



__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

Re: [Elecraft] Upper limits of KPA500?

[Jack Brindle via Elecraft]

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  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:Elecraft@mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to jackbrin...@me.com 

__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com 

[Elecraft] Upper limits of KPA500?

[Dave Cole]

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:Elecraft@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com