KX2 heatsink

[Irma & Linas(LY2H)]

Hello folks,
I am looking for the practical , empyrical, real info based on the
individual measurements of the maximum Key-down time/temperature at the 10w
output of the KX2 before it drops down to 5 W issuing a message of "HI
TEMP". I would also like to learn about comparison of the KX2 stock
heatsink vs the Pro-audio Engineering KX22 product.

The reason is that I have decided to install the KX22 on my KX2 ( # 148*)
after a short dx-pedition to Aland islands in May. I was handling quite a
pile-up from the hotel room and after some 5 min of intensive CQ-ing and
answering on CW the PA temperature gone up to 59-60C degrees and the power
dropped down to 5 W and it was frustrating :)
Today I have installed the PAE KX22 heatsink. The key-down at 10 W into a
dummy load in CW mode lasted for around 3 minutes starting from the ambient
temp. 27C. I don't think this is very impressive baring in mind the
Pro-audio's  claim of the 250% key-down time improvement. Unfortunately, I
was not so smart to test the key-down time with the stock heatsink before I
changed it to the new one, :) But I remember Wayne was posting  here in the
previous thread something abt 7 min of key-down at 10W... So, with the 250%
improvement with the KX22 it should  last... for some 24 min?! in my case,
It doesn't sound very realistic , neither 7 min with the stock heatsink,
nor 24 min with the Pro-Audio ( maybe ,bad thermal contact, not enough of
grease?). That's why it would be very interesting  to compare the real-life
empyrical data of the other KX2 owners.

73! Linas LY2H
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[Don Wilhelm]

Linas,

I know Howie (owner of Pro Audio Engineering) and consider him to be a
personal friend.  I also know he is a meticulous engineer, and very
likely has full data from his testing.
I suggest sending him a direct email request.

The results you posted - only 3 minutes keydown at 10 watts indicate to
me that you may have a problem with your KX2.  That is even
substantially less than the time Wayne posted resulting from his tests
using the stock heatsink.

I would check to be certain the PA transistors are in full contact with
the heatsink.

Sorry, but I do not have a KX2 to give you additional information.
Perhaps someone else will volunteer.

73,
Don W3FPR


On 6/18/2017 5:32 PM, Irma & Linas(LY2H) wrote:
> Hello folks,
> I am looking for the practical , empyrical, real info based on the
> individual measurements of the maximum Key-down time/temperature at the 10w
> output of the KX2 before it drops down to 5 W issuing a message of "HI
> TEMP". I would also like to learn about comparison of the KX2 stock
> heatsink vs the Pro-audio Engineering KX22 product.
>
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[Clay Autery]

Definitely sounds like a heatsink to source interface issue.  Either not
a flush enough fit, missing, wrong, or not appropriately applied thermal
compound...

73,

______________________
Clay Autery, KY5G

On 6/18/2017 5:26 PM, Don Wilhelm wrote:
> I would check to be certain the PA transistors are in full contact
> with the heatsink.

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[wayne burdick]

Auto power reduction happens at 63 C. But it may very well have gone down to 55 C awhile after dropping to 5 W.

Wayne
N6KR

----
http://www.elecraft.com

> On Jun 18, 2017, at 4:38 PM, Ron D'Eau Claire <[hidden email]> wrote:
>
> Sri, I meant the temp was 55C, not 45C after the automatic power reduction
> kicked in.
>
> 73 Ron AC7AC
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Ron D'Eau Claire
> Sent: Sunday, June 18, 2017 4:28 PM
> To: 'Irma & Linas(LY2H)'; [hidden email]
> Subject: Re: [Elecraft] KX2 heatsink
>
> Fired up my "stock from the factory" KX2 into a dummy load at 10 watts, key
> down, and it dropped to 5 watts after 4 minutes running from a 13.8 vdc
> supply.  PA temp was about 45C.
>
> Hope that helps with your analysis.
>
> 73, Ron AC7AC
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Irma & Linas(LY2H)
> Sent: Sunday, June 18, 2017 2:33 PM
> To: [hidden email]
> Subject: [Elecraft] KX2 heatsink
>
> Hello folks,
> I am looking for the practical , empyrical, real info based on the
> individual measurements of the maximum Key-down time/temperature at the 10w
> output of the KX2 before it drops down to 5 W issuing a message of "HI
> TEMP". I would also like to learn about comparison of the KX2 stock heatsink
> vs the Pro-audio Engineering KX22 product.
>
> The reason is that I have decided to install the KX22 on my KX2 ( # 148*)
> after a short dx-pedition to Aland islands in May. I was handling quite a
> pile-up from the hotel room and after some 5 min of intensive CQ-ing and
> answering on CW the PA temperature gone up to 59-60C degrees and the power
> dropped down to 5 W and it was frustrating :) Today I have installed the PAE
> KX22 heatsink. The key-down at 10 W into a dummy load in CW mode lasted for
> around 3 minutes starting from the ambient temp. 27C. I don't think this is
> very impressive baring in mind the Pro-audio's  claim of the 250% key-down
> time improvement. Unfortunately, I was not so smart to test the key-down
> time with the stock heatsink before I changed it to the new one, :) But I
> remember Wayne was posting  here in the previous thread something abt 7 min
> of key-down at 10W... So, with the 250% improvement with the KX22 it should
> last... for some 24 min?! in my case, It doesn't sound very realistic ,
> neither 7 min with the stock heatsink, nor 24 min with the Pro-Audio ( maybe
> ,bad thermal contact, not enough of grease?). That's why it would be very
> interesting  to compare the real-life empyrical data of the other KX2
> owners.
>
> 73! Linas LY2H
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[John Oppenheimer]

Hi Linas,

My KX2 dropped from 10W to 5W at 3 minutes 48 seconds of key down,
starting at 25C.

John KN5L
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[wayne burdick]

> John Oppenheimer <[hidden email]> wrote:
>
> My KX2 dropped from 10W to 5W at 3 minutes 48 seconds of key down,
> starting at 25C.



This is fairly typical. I’ve seen some as high as 8 minutes.

Some tips related to PA temperature:

- Make sure all right-side hardware is tightened

- Running from a lower supply voltage (e.g., the 11 V internal battery)
  should reduce power dissipation

- Keep the radio out of direct sunlight when possible

- In contests, use hunt-and-pounce operation, not continuous CQing
  (this tip applies to QRP operation in general; listen more
  than you transmit)

Wayne
N6KR

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[John Oppenheimer]

On 06/19/2017 10:41 AM, Wayne Burdick wrote:
> - Running from a lower supply voltage (e.g., the 11 V internal battery)
>   should reduce power dissipation

This is counter to what I had thought! But:

With external 13.8V input, power lowered to 5W at 3 minutes 48 seconds.

With internal battery, I gave up at after 8 minutes, with PA temperature
at 60C.

Maybe a new KX2 11V power supply is needed for dx-peditions similar to
Linas' adventure to Aland Islands.

John KN5L
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[K9MA]

On 6/19/2017 16:13, John Oppenheimer wrote:
> On 06/19/2017 10:41 AM, Wayne Burdick wrote:
>> - Running from a lower supply voltage (e.g., the 11 V internal battery)
>>    should reduce power dissipation
> This is counter to what I had thought!

This makes perfect sense.  The closer the PA operates to saturation, the
more efficient it is.  Linearity, of course, is another matter entirely.

--
Scott  K9MA

[hidden email]

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[John Oppenheimer]

On 06/19/2017 10:41 AM, Wayne Burdick wrote:
> - Running from a lower supply voltage (e.g., the 11 V internal battery)
>   should reduce power dissipation

With external 13.8V input, power lowered to 5W at 3 minutes 48 seconds.

With internal battery, at 8 minutes, the PA temperature was 60C.

John KN5L
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