Re: [Elecraft] KX3 Heatsink discussion

[Howard Hoyt]

Hi Jan,

Elecraft designed the KX twins to run with maximum efficiency, so up to 
10 watts, it is the more efficient PA in the KX3 which supplies the 
output power with the KXPA100 in bypass, and when more than 10 watts is 
dialed in the KXPA100 is enabled, and the KX3 throttles back to make the 
KXPA100 output whatever is desired.


Cheers & 73,

Howie - WA4PSC

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Re: [Elecraft] KX3 Heatsink discussion

[Jan]

OH ~ I think we all understand that the word "heat-sink" implies that it 
might/will get warm :-)


BUT ~ I  originally asked about the "heating" of the KX3 when driving 
the KXPA100 at 20W


SO ~ I experimented this morning with adjusting the power OUT of the KX3 
while driving the KXPA100 amplifier.  With rotation of the Power knob on 
the KX3, it climbs to 10W [as measured at the Output of the KX3] and 
with further rotation of the knob, it drops to less than 2W  for ~ 40W 
out from the Amplifier and about 4W yields ~ 100W from the Amp.


THUS ~ why should the KX3 heat-up when driving an amplifier 

Cheers, Jan K1ND


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[Elecraft] KX3 Heatsink discussion

[Howard Hoyt]

Sorry of this appears twice, I got a bounce on the first submission:

The Pro Audio Engineering Kx32 Heatsink has more surface area than any 
other commercially available KX3 heatsink.  Regarding mass, more is not 
necessarily better.  If you take two heatsinks with the same surface 
area, on the initial key-down the one with more mass gives a longer 
initial warmup time.  Unfortunately it also retains heat longer, meaning 
on the subsequent transmit cycles, it still retains heat from the 
previous cycle.  We strove to minimize the mass of our heatsinks, the 
limitation ended up being rigidity and resistance of the fins to damage.


The limitation on convective heatsink efficiency is not the thermal 
conductivity of aluminum, it is surface area.  Our tests show very 
little thermal Δ (delta if your browser is ASCII only!) across the area 
of any given heatsink of almost any convective design.  This is because 
the limitation is dissipation due to convection.  If you model the 
thermal path as a series string of resistances, the aluminum is very low 
resistance and the surface to air resistance is very high.


For more information visit our website!

Cheers & 73,

Howie
Pro Audio Engineering

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Re: [Elecraft] KX3 Heatsink discussion

[Wayne Burdick]

Actually, that’s 63 C at the PA device location on the PC board. The outside 
surface of the heat sink itself is quite a bit lower in temperature.

Wayne
N6KR


> On Aug 6, 2017, at 11:39 AM, Wayne Burdick  wrote:
> 
> The KX3 and KX2 max heat sink temperature is 63 C. At that point power is 
> automatically dropped to 5 W. If it reaches the max temp again, transmit is 
> exited.
> 
> Wayne
> N6KR
> 
> 
> 
>> On Aug 6, 2017, at 10:27 AM, Jim Brown  wrote:
>> 
>> A well designed output stage SHOULD be hot to the touch. The temperature 
>> component of protection in Elecraft output stages seems to kick in when the 
>> internal temperature approaches 70 deg C.  You can see this, for example, by 
>> watching temperature in the KPA500 and listening to fan speed. The function 
>> of the heat sink is to act as a conductor between the semiconductor 
>> junctions and the surrounding environment, and increased mass acts as a sort 
>> of buffer.
>> 
>> 73, Jim K9YC
>> 
>> On 8/5/2017 2:53 PM, Jan wrote:
>>> ""I've been doing a lot of FT-8 using my KX3 and my KXPA100 at 20 watts,
>>> and have noticed that the KX3 is heating up quite a bit and is almost
>>> hot to the touch""
>>> 
>>> Why should the KX3 be heating up, when the AMP is running only 20W ?
>>> Is the KX3 "drive" not backed-down at this level ?? HELP
>> 
>> 
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Re: [Elecraft] KX3 Heatsink discussion

[Wayne Burdick]

The KX3 and KX2 max heat sink temperature is 63 C. At that point power is 
automatically dropped to 5 W. If it reaches the max temp again, transmit is 
exited.

Wayne
N6KR



> On Aug 6, 2017, at 10:27 AM, Jim Brown  wrote:
> 
> A well designed output stage SHOULD be hot to the touch. The temperature 
> component of protection in Elecraft output stages seems to kick in when the 
> internal temperature approaches 70 deg C.  You can see this, for example, by 
> watching temperature in the KPA500 and listening to fan speed. The function 
> of the heat sink is to act as a conductor between the semiconductor junctions 
> and the surrounding environment, and increased mass acts as a sort of buffer.
> 
> 73, Jim K9YC
> 
> On 8/5/2017 2:53 PM, Jan wrote:
>> ""I've been doing a lot of FT-8 using my KX3 and my KXPA100 at 20 watts,
>> and have noticed that the KX3 is heating up quite a bit and is almost
>> hot to the touch""
>> 
>> Why should the KX3 be heating up, when the AMP is running only 20W ?
>> Is the KX3 "drive" not backed-down at this level ?? HELP
> 
> 
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Re: [Elecraft] KX3 Heatsink discussion

[Jim Brown]

A well designed output stage SHOULD be hot to the touch. The temperature 
component of protection in Elecraft output stages seems to kick in when 
the internal temperature approaches 70 deg C.  You can see this, for 
example, by watching temperature in the KPA500 and listening to fan 
speed. The function of the heat sink is to act as a conductor between 
the semiconductor junctions and the surrounding environment, and 
increased mass acts as a sort of buffer.


73, Jim K9YC

On 8/5/2017 2:53 PM, Jan wrote:

""I've been doing a lot of FT-8 using my KX3 and my KXPA100 at 20 watts,
and have noticed that the KX3 is heating up quite a bit and is almost
hot to the touch""

Why should the KX3 be heating up, when the AMP is running only 20W ?
Is the KX3 "drive" not backed-down at this level ?? HELP



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[Elecraft] KX3 Heatsink discussion

[Jan]

I'm puzzled by the comment posted yesterday:  by Jim W7JR

""I've been doing a lot of FT-8 using my KX3 and my KXPA100 at 20 watts,
and have noticed that the KX3 is heating up quite a bit and is almost
hot to the touch""

Why should the KX3 be heating up, when the AMP is running only 20W ?
Is the KX3 "drive" not backed-down at this level ?? HELP

Cheers, Jan K1ND

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Re: [Elecraft] KX3 heatsink question

[David Gow]

I have a later serial number with the improved heatsink and find it
completely satisfactory for PSK31 in typical QSO use.  I usually run about
8 watts and do monitor the final amplifier temperature  via the  screen
display.  It never gets anywhere near the shut-down level or "hot" to the
touch.  I do live in Seattle so the ambient temperature in the shack seldom
exceeds 80F and is mostly around the 68F furnace setting and also the
typical spring summer fall 60-75 daytime temperature here in the land of
eternal rain 9 months of the year and drought with sunny mild temperatures
for the other three.

Dave W7VM

On Tue, Mar 21, 2017 at 4:50 AM, Jerry <w...@jetbroadband.com> wrote:

> I bought a ProAudio heatsink for my KX# about 3 or 4 years ago and found
> that since I could read and handle some relatively simple hand tools,
> assembly was easy and straight forth. Using RTTY at full power, it got only
> warm - made a nice ham warmer in the colder mountain areas. The price you
> pay for ProAudio is well worth it.
>
> Best regards,
>
> Jerry, W1IE
>
>
> -Original Message-
> From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
> Howard
> Hoyt
> Sent: Tuesday, March 21, 2017 3:11 AM
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] KX3 heatsink question
>
> Hi Rich,
>
> The advantages of a real aftermarket heatsink (not the poorly designed
> imports) is rapid thermal recovery after each transmit cycle and less heat
> re-radiated into the rig.  The import with the rounded fin root as well as
> others have a less optimum volume to surface area ratio and stay much
> hotter
> between transmit cycles. Also a good heatsink will allow higher power
> operation in temperatures we sometimes find ourselves when operating on
> picnic tables and the like in the summer!
>
> (commercial content) We find most of our customers who are occasional
> digital users are satisfied with the smaller of our two heatsinks, model
> Kx31, but the JT mode enthusiasts, especially contesters are going for the
> slightly larger Kx32 model.  Much more info on our website.  Just our
> experience...YMMV
>
> Howie - WA4PSC
> www.proaudioeng.com
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Re: [Elecraft] KX3 heatsink question

[Jerry]

I bought a ProAudio heatsink for my KX# about 3 or 4 years ago and found
that since I could read and handle some relatively simple hand tools,
assembly was easy and straight forth. Using RTTY at full power, it got only
warm - made a nice ham warmer in the colder mountain areas. The price you
pay for ProAudio is well worth it.

Best regards,

Jerry, W1IE


-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Howard
Hoyt
Sent: Tuesday, March 21, 2017 3:11 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KX3 heatsink question

Hi Rich,

The advantages of a real aftermarket heatsink (not the poorly designed
imports) is rapid thermal recovery after each transmit cycle and less heat
re-radiated into the rig.  The import with the rounded fin root as well as
others have a less optimum volume to surface area ratio and stay much hotter
between transmit cycles. Also a good heatsink will allow higher power
operation in temperatures we sometimes find ourselves when operating on
picnic tables and the like in the summer!

(commercial content) We find most of our customers who are occasional
digital users are satisfied with the smaller of our two heatsinks, model
Kx31, but the JT mode enthusiasts, especially contesters are going for the
slightly larger Kx32 model.  Much more info on our website.  Just our
experience...YMMV

Howie - WA4PSC
www.proaudioeng.com
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Re: [Elecraft] KX3 heatsink question

[Howard Hoyt]

Hi Rich,

The advantages of a real aftermarket heatsink (not the poorly designed 
imports) is rapid thermal recovery after each transmit cycle and less 
heat re-radiated into the rig.  The import with the rounded fin root as 
well as others have a less optimum volume to surface area ratio and stay 
much hotter between transmit cycles. Also a good heatsink will allow 
higher power operation in temperatures we sometimes find ourselves when 
operating on picnic tables and the like in the summer!


(commercial content) We find most of our customers who are occasional 
digital users are satisfied with the smaller of our two heatsinks, model 
Kx31, but the JT mode enthusiasts, especially contesters are going for 
the slightly larger Kx32 model.  Much more info on our website.  Just 
our experience...YMMV


Howie - WA4PSC
www.proaudioeng.com
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Re: [Elecraft] KX3 heatsink question

[Edward R Cole]

Look at: http://www.kl7uw.com/KX3.htm

Prices may have changed.  Hopefully links still good.
Combination of after-market heat sink and temp compensation procedure.

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


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Re: [Elecraft] KX3 heatsink question

[Don Wilhelm]

Ed,

The KX3 "wrap-under" heatsink is adequate for most modes.  However if 
you are using data modes with long transmit periods at power levels 
above 7 or 8 watts, you might want to consider an aftermarket heatsink.


Give it a try and feel the heatsink after several transmission periods. 
It will be warm, but you should be able to hold your hand on the 
heatsink without discomfort.  That is always a good test for OK vs. Too Hot.


73,
Don W3FPR

On 3/20/2017 1:17 PM, Eddy Avila wrote:

With some expert help from the Elecraft forum, I'm up and running JT65/9 using 
my new KX3.


My rig's s/n is 9403, do I still need to consider upgrading to the after-market 
heatsink or the one that came with my new KX3 (9403) sufficient for most data 
modes?


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Re: [Elecraft] KX3 heatsink question

[rich hurd WC3T]

I have a KX3 with the new heatsink (S/N 7XXX) and although the heatsink
gets warm during ops, I've not had any issues running the high duty cycle
modes with the factory model.   I am not a heavy duty digital mode user, so
YMMV; but I'm avoiding the required surgery that the heatsink would
require.   :)

On Mon, Mar 20, 2017 at 1:17 PM, Eddy Avila  wrote:

> With some expert help from the Elecraft forum, I'm up and running JT65/9
> using my new KX3.
>
>
> My rig's s/n is 9403, do I still need to consider upgrading to the
> after-market heatsink or the one that came with my new KX3 (9403)
> sufficient for most data modes?
>
>
> tnx and 73
>
>
> k6sdw
>
>
> ed
>
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-- 
73 (or 72 for the QRP folks),
Rich Hurd / WC3T
Northampton County RACES
EPA-ARRL Public Information Officer for Scouting
Latitude: 40.761621 Longitude: -75.288988  Grid: *FN20is*
40°45.68' N 75°17.33' W
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[Elecraft] KX3 heatsink question

[Eddy Avila]

With some expert help from the Elecraft forum, I'm up and running JT65/9 using 
my new KX3.


My rig's s/n is 9403, do I still need to consider upgrading to the after-market 
heatsink or the one that came with my new KX3 (9403) sufficient for most data 
modes?


tnx and 73


k6sdw


ed

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[Elecraft] KX3 Heatsink issue

[Howard Hoyt]

Hi all,

I have had quite a few inquiries regarding installing our aftermarket 
Kx31 heatsink in place of the newest Elecraft L shaped heatsink.  In 
deference to Eric and Wayne who graciously offer occasional posts in 
this list to vendors, I'll not discuss it here. Please see our FAQ on 
this issue at: https://proaudioeng.com/products/pae-kx31-heatsink-kit/


Cheers  73,

Howie - WA4PSC
www.proaudioeng.com
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Re: [Elecraft] KX3 heatsink

[Calvin Jones]

Hi,
This was over on the KX3 Yahoo group
http://www.bigskyspaces.com/w7gj/KX3HeatSinks.htm

Calvin
KA7MAY

On Nov 19, 2012, at 10:36 AM, Niel Skousen nskou...@talisman-intl.com wrote:

 I recall someone posting a heatsink that they'd done for the KX3, and were 
 intending to provide an aftermarket heatsink to the group.Can anyone 
 forward me a link or email address to follow up with ?
 
 Thanks
 Niel
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[Elecraft] KX3 heatsink

[Niel Skousen]

I recall someone posting a heatsink that they'd done for the KX3, and were 
intending to provide an aftermarket heatsink to the group.Can anyone 
forward me a link or email address to follow up with ?

Thanks
Niel
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