Re: [Elecraft] KLPA3A power transistor thermal stress concerns

2017-10-28 Thread Clay Autery 
If anyone requires someone to assist in REALLY getting "nutty" about 
thermal control/dissipation on electronic components, I'd be happy to 
oblige from my experience.
I have had some fairly extensive hand-on experience.  Once upon a time, 
I invented Arctic Silver thermal compound and adhesive. Before, during, 
and after that time I spent thousands of hours working on custom thermal 
control solutions.


It's an addiction.

73,
Clay KY5G


On 10/27/2017 6:00 PM, Don Wilhelm wrote:

Bill is entirely correct.
Once in my prior career, I did a study of Mean Time Between Failure 
for IC circuits (same applies to transistors).  That study had to 
consider the case temperature of the IC (or transistor) with respect 
to the junction temperature.
The specification for the IC or transistor package will include a 
thermal resistance parameter, which must be considered to obtain the 
maximum temperature for the case of the device.


Bill's comment about the screw tightness is entirely correct - the 
heat of the device case must be transferred to the heatsink in an 
efficient manner.


73,
Don W3FPR

On 10/27/2017 6:07 PM, Nr4c wrote:
Yes. But I believe that is Junction temperature, not case on heatsink 
temp.  Remember the case bottom is heatsink for those. Make sure 
screws are tight.


Sent from my iPhone
...nr4c. bill



On Oct 27, 2017, at 12:19 PM, N2TK, Tony  wrote:

50C is not hot for a transistor. Commercial transistors are usually 
speced to 85C. JANS (space) transistors are speced to 125C and 
actually baked without bias for 320 hours at 200C. The hFE is 
measured before and after to check for change.

__
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] KLPA3A power transistor thermal stress concerns

2017-10-27 Thread Don Wilhelm 

Bill is entirely correct.
Once in my prior career, I did a study of Mean Time Between Failure for 
IC circuits (same applies to transistors).  That study had to consider 
the case temperature of the IC (or transistor) with respect to the 
junction temperature.
The specification for the IC or transistor package will include a 
thermal resistance parameter, which must be considered to obtain the 
maximum temperature for the case of the device.


Bill's comment about the screw tightness is entirely correct - the heat 
of the device case must be transferred to the heatsink in an efficient 
manner.


73,
Don W3FPR

On 10/27/2017 6:07 PM, Nr4c wrote:

Yes. But I believe that is Junction temperature, not case on heatsink temp.  
Remember the case bottom is heatsink for those. Make sure screws are tight.

Sent from my iPhone
...nr4c. bill



On Oct 27, 2017, at 12:19 PM, N2TK, Tony  wrote:

50C is not hot for a transistor. Commercial transistors are usually speced to 
85C. JANS (space) transistors are speced to 125C and actually baked without 
bias for 320 hours at 200C. The hFE is measured before and after to check for 
change.



__
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] KLPA3A power transistor thermal stress concerns

2017-10-27 Thread Nr4c 
Yes. But I believe that is Junction temperature, not case on heatsink temp.  
Remember the case bottom is heatsink for those. Make sure screws are tight. 

Sent from my iPhone
...nr4c. bill


> On Oct 27, 2017, at 12:19 PM, N2TK, Tony  wrote:
> 
> 50C is not hot for a transistor. Commercial transistors are usually speced to 
> 85C. JANS (space) transistors are speced to 125C and actually baked without 
> bias for 320 hours at 200C. The hFE is measured before and after to check for 
> change.
> 73
> N2TK, Tony
> 
> Sent from my iPad
> 
>> On Oct 24, 2017, at 8:23 PM, Don Wilhelm  wrote:
>> 
>> Nick,
>> 
>> Yes, I believe that should be no problem.
>> 
>> 73,
>> Don W3FPR
>> 
>>> On 10/24/2017 8:57 PM, Nick - VE3EY wrote:
>>> Hi Don
>>> 
>>> Good question.   I happen to have a Infrared Thermometer.   After bashing 
>>> at it for about 20 minutes, the temperature in the vicinity of two 
>>> transistors (as measured against the bottom cover) peaked at 50 degrees 
>>> Celsius (122 F) but it did not go beyond that.  I ran the rig at 10 watts 
>>> on 10 meters which is where most of the drive power is needed.
>>> 
>>> I suppose that should be OK than.
>>> 
>>> 73 and thanks for your feedback,
>>> 
>> 
>> __
>> 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 tony@verizon.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 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] KLPA3A power transistor thermal stress concerns

2017-10-27 Thread N2TK, Tony 
50C is not hot for a transistor. Commercial transistors are usually speced to 
85C. JANS (space) transistors are speced to 125C and actually baked without 
bias for 320 hours at 200C. The hFE is measured before and after to check for 
change.
73
N2TK, Tony

Sent from my iPad

> On Oct 24, 2017, at 8:23 PM, Don Wilhelm  wrote:
> 
> Nick,
> 
> Yes, I believe that should be no problem.
> 
> 73,
> Don W3FPR
> 
>> On 10/24/2017 8:57 PM, Nick - VE3EY wrote:
>> Hi Don
>> 
>> Good question.   I happen to have a Infrared Thermometer.   After bashing at 
>> it for about 20 minutes, the temperature in the vicinity of two transistors 
>> (as measured against the bottom cover) peaked at 50 degrees Celsius (122 F) 
>> but it did not go beyond that.  I ran the rig at 10 watts on 10 meters which 
>> is where most of the drive power is needed.
>> 
>> I suppose that should be OK than.
>> 
>> 73 and thanks for your feedback,
>> 
> 
> __
> 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 tony@verizon.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] KLPA3A power transistor thermal stress concerns

2017-10-26 Thread Wes Stewart 

Don't think so from the description Wayne gave on the KX3 Yahoo group.

Wes N7WS

On 10/25/2017 8:48 AM, Ignacy wrote:

I assume that the LPA in K3 is
similar to the amp in KX3.

Ignacy, NO9E


__
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] KLPA3A power transistor thermal stress concerns

2017-10-25 Thread Wes Stewart 

Did they do IMD as a function of frequency?



On 10/25/2017 8:48 AM, Ignacy wrote:

Seems a bit artificial problem, unless someone is driving an amp that
requires 12 W. My modified Expert 1.3k-fa requires about 6W to 8 W for 1 KW
output.
  
If a serious concern, increase voltage to 15V. The Yahoo KX3 group has

graphs of IMD3 as a function of power and voltage. Increasing voltage at 12
W by 1 V decreased IMD3 by about 10 db. I assume that the LPA in K3 is
similar to the amp in KX3.

Ignacy, NO9E




__
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] KLPA3A power transistor thermal stress concerns

2017-10-25 Thread Wes Stewart 
Personally, I would, and do, avoid that region.  The difference in received 
strength between 10 and 12W is imperceptible if the HPA isn't installed. If it 
is installed, crank the power up to 20 or so and you're out of danger.


Wes  N7WS



On 10/24/2017 8:31 AM, Mike via Elecraft wrote:

The K3/100 switches to the KPA3A at 12 watts.  So is there a 2w range
(10-12w) where the KLPA3A is putting out unacceptable IMD?  Is there a way  to
make the switch at 10w, or should we just avoid that 2w "danger zone"?
  
73
  
Mike KD8RQE
  
  
In a message dated 10/24/2017 10:56:38 A.M. Eastern Daylight Time,

wes_n...@triconet.org  writes:

The  K3/10 will output 12W.

That said, based on IMD measurements I have  performed I would NEVER run a
K3/10
at 12W out.  Frankly, with my K3S  with the latest rev KLPA3A to keep 3rd
order
IMD below 30 dBc, I would  throttle it back even more above 18 MHz.

Wes  N7WS




__
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] KLPA3A power transistor thermal stress concerns

2017-10-25 Thread Ignacy 
Seems a bit artificial problem, unless someone is driving an amp that
requires 12 W. My modified Expert 1.3k-fa requires about 6W to 8 W for 1 KW
output.
 
If a serious concern, increase voltage to 15V. The Yahoo KX3 group has
graphs of IMD3 as a function of power and voltage. Increasing voltage at 12
W by 1 V decreased IMD3 by about 10 db. I assume that the LPA in K3 is
similar to the amp in KX3.  

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] KLPA3A power transistor thermal stress concerns

2017-10-25 Thread Don Wilhelm 

Nick,

Yes, I believe that should be no problem.

73,
Don W3FPR

On 10/24/2017 8:57 PM, Nick - VE3EY wrote:

Hi Don

Good question.   I happen to have a Infrared Thermometer.   After 
bashing at it for about 20 minutes, the temperature in the vicinity of 
two transistors (as measured against the bottom cover) peaked at 50 
degrees Celsius (122 F) but it did not go beyond that.  I ran the rig 
at 10 watts on 10 meters which is where most of the drive power is 
needed.


I suppose that should be OK than.

73 and thanks for your feedback,



__
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] KLPA3A power transistor thermal stress concerns

2017-10-25 Thread Nick - VE3EY 
Hi Don

Good question.   I happen to have a Infrared Thermometer.After bashing
at it for about 20 minutes, the temperature in the vicinity of two
transistors (as measured against the bottom cover) peaked at 50 degrees
Celsius (122 F) but it did not go beyond that.  I ran the rig at 10 watts
on 10 meters which is where most of the drive power is needed.

I suppose that should be OK than.

73 and thanks for your feedback,
Nick
VE3EY

On Tue, Oct 24, 2017 at 9:23 AM, Don Wilhelm  wrote:

> Nick,
>
> It all depends on your perception of "fairly hot".
>
> My 'rule of thumb' is that if you can hold your fingers on the surface,
> then it is not too hot.
>
> 73,
> Don W3FPR
>
>
>
> On 10/24/2017 7:27 AM, Nick - VE3EY wrote:
>
>> I have a K3s/10 (12 watt version) which I intend to use in the upcoming cq
>> ww cw contest.  This unit does not have KPA3A power brick and cooling fans
>> installed.
>>
>> While doing some trial runs I noticed that the area around the KLPA3A
>> power
>> transistors is getting fairly hot after prolonged contest use.  My guess
>> is
>> the transistors are working harder when used as finals.  The rig needs to
>> produce between 6 and 12 watts to properly drive the SS amp I intend to
>> use.
>>
>
__
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] KLPA3A power transistor thermal stress concerns

2017-10-24 Thread j...@kk9a.com 
I agree and I have previously mentioned this on the Elecraft list. it
would be nice if you could control when the 100W PA engages. I would
prefer 10 watts.

John KK9A



KD8RQE wrote:

The K3/100 switches to the KPA3A at 12 watts.  So is there a 2w range
(10-12w) where the KLPA3A is putting out unacceptable IMD?  Is there a way
 to
make the switch at 10w, or should we just avoid that 2w "danger zone"?

73

Mike KD8RQE


__
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] KLPA3A power transistor thermal stress concerns

2017-10-24 Thread Mike via Elecraft 
The K3/100 switches to the KPA3A at 12 watts.  So is there a 2w range  
(10-12w) where the KLPA3A is putting out unacceptable IMD?  Is there a way  to 
make the switch at 10w, or should we just avoid that 2w "danger zone"?
 
73
 
Mike KD8RQE
 
 
In a message dated 10/24/2017 10:56:38 A.M. Eastern Daylight Time,  
wes_n...@triconet.org writes:

The  K3/10 will output 12W.

That said, based on IMD measurements I have  performed I would NEVER run a 
K3/10 
at 12W out.  Frankly, with my K3S  with the latest rev KLPA3A to keep 3rd 
order 
IMD below 30 dBc, I would  throttle it back even more above 18 MHz.

Wes  N7WS


On  10/24/2017 6:27 AM, Rose wrote:
> Nick,
>
> What is the "12  watt" version you're referring to?
>
> 73
>
>  K0PP

__
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  kd8...@aol.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] KLPA3A power transistor thermal stress concerns

2017-10-24 Thread Wes Stewart 

The K3/10 will output 12W.

That said, based on IMD measurements I have performed I would NEVER run a K3/10 
at 12W out.  Frankly, with my K3S with the latest rev KLPA3A to keep 3rd order 
IMD below 30 dBc, I would throttle it back even more above 18 MHz.


Wes  N7WS


On 10/24/2017 6:27 AM, Rose wrote:

Nick,

What is the "12 watt" version you're referring to?

73

K0PP


__
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] KLPA3A power transistor thermal stress concerns

2017-10-24 Thread Rose 
Nick,

What is the "12 watt" version you're referring to?

73

K0PP

On Oct 24, 2017 5:29 AM, "Nick - VE3EY"  wrote:

> I have a K3s/10 (12 watt version) which I intend to use in the upcoming cq
> ww cw contest.  This unit does not have KPA3A power brick and cooling fans
> installed.
>
> While doing some trial runs I noticed that the area around the KLPA3A power
> transistors is getting fairly hot after prolonged contest use.  My guess is
> the transistors are working harder when used as finals.  The rig needs to
> produce between 6 and 12 watts to properly drive the SS amp I intend to
> use.
>
> Looking for some opinions:
>
> 1.  Don't worry about it.  I am paranoid.  The KLPA3A power transistors can
> sustain the rigor of 40+ hours use in the contest.  Just make sure they are
> properly fastened as directed in the assembly manual.
>
> 2.  Rig up some passive thermal cooling.   Perhaps a heat-sink underneath
> the rig to allow heat to dissipate.
>
> 3.  Mount a 12v cooling fan somewhere to allow for airflow underneath the
> radio to take away excess heat.
>
>
>
> 73
>
> Nick VE3EY
> __
> 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 elecraftcov...@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] KLPA3A power transistor thermal stress concerns

2017-10-24 Thread Don Wilhelm 

Nick,

It all depends on your perception of "fairly hot".

My 'rule of thumb' is that if you can hold your fingers on the surface, 
then it is not too hot.


73,
Don W3FPR


On 10/24/2017 7:27 AM, Nick - VE3EY wrote:

I have a K3s/10 (12 watt version) which I intend to use in the upcoming cq
ww cw contest.  This unit does not have KPA3A power brick and cooling fans
installed.

While doing some trial runs I noticed that the area around the KLPA3A power
transistors is getting fairly hot after prolonged contest use.  My guess is
the transistors are working harder when used as finals.  The rig needs to
produce between 6 and 12 watts to properly drive the SS amp I intend to
use.

__
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] KLPA3A power transistor thermal stress concerns

2017-10-24 Thread Nick - VE3EY 
I have a K3s/10 (12 watt version) which I intend to use in the upcoming cq
ww cw contest.  This unit does not have KPA3A power brick and cooling fans
installed.

While doing some trial runs I noticed that the area around the KLPA3A power
transistors is getting fairly hot after prolonged contest use.  My guess is
the transistors are working harder when used as finals.  The rig needs to
produce between 6 and 12 watts to properly drive the SS amp I intend to
use.

Looking for some opinions:

1.  Don't worry about it.  I am paranoid.  The KLPA3A power transistors can
sustain the rigor of 40+ hours use in the contest.  Just make sure they are
properly fastened as directed in the assembly manual.

2.  Rig up some passive thermal cooling.   Perhaps a heat-sink underneath
the rig to allow heat to dissipate.

3.  Mount a 12v cooling fan somewhere to allow for airflow underneath the
radio to take away excess heat.



73

Nick VE3EY
__
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