K3 COOLING VENTS

[Tony Scesny]

Hi,

     There have been enough posts here about the temperature inside the
K3 to start me thinking.   Mine also gets very WARM on the right side by
U12 and U13.  You all know how "boxed in"  the Front side of the K3 has
become and now we are looking at additional features being added to the
inside of the box. The way the cooling fan is now, there is little or no
circulation of air in the front side of the K3.  Another poster wanted
to add bigger fans but, you know, that will not solve the heat problem
because the air can't get to where it needs to go.  I would like to
"CROSS VENTILATE" the front area by adding cooling vents, similar to the
configuration of the speaker vents,  to both side panels.  There does
not seem to be any worry about RF leakage at the rear vents where the
AMP is and the side vents can be fashioned the same way.  I know that
Wayne feels that the cooling is adequate but,  I think this would be a
worthy modification at this point, if only to let the HOT AIR ...OUT.

If someone knows how to punch out this configuration, I would gladly
supply the panels and pay any costs involved.

73's  and  Thanks.

Tony      K2ZLS at OPTONLINE  dot  NET
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[Brendan Minish]

On Thu, 2009-05-14 at 17:05 -0400, K2ZLS wrote:
> Hi,
>
>      There have been enough posts here about the temperature inside the
> K3 to start me thinking.   Mine also gets very WARM on the right side by
> U12 and U13.
<--snip-->
>  I think this would be a
> worthy modification at this point, if only to let the HOT AIR ...OUT.

Don't do it, it's not needed and it may mess up air circulation
elsewhere causing hot spots.
The heat at this location is not hot air inside making the case warm
it's the side of the case being used as an (ample) heat-sink for the
directly attached Voltage regulators.

Warmth here IS NOT a symptom of much hotter stuff inside as would have
been the case with a 'hollow state' radio, simply that the side panel is
working as intended to heatsink the voltage regulators bolted directly
to it.  


--
73
Brendan EI6IZ

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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Tony Scesny]

Thanks to Brendan and all the responders:

  I have received several answers similar to yours regarding the heat
sink effect.   But,  I already knew that.  The reason I'm bringing this
up is that the concern for "hot spots" is already there.  After running
the K3 hard, try powering down, remove power and the top cover.  Feel
around the front side and you will notice the warmth of the display,  
the other boards and the KRX3 box, which has NO ventilation inside and
is a heat sink by itself.  If you examine the air flow you can't help
but see that the air movement DOESN'T GET to these areas. It's
concentrated in the area around the AMP enclosure.  That's my point.  
The K3 CAN be improved if a little more attention is paid to draining
this heat supply more efficiently instead of accepting the rise in heat
as a GOOD thing.  I think improving the ventilation is the key here and
maybe you are right,  my idea of cross ventilation may not be the best
thing.  Maybe, instead of drawing ALL cooling air from the top opening,  
a side vent is installed to provide an additional source of cooling air
that will find its own way to the output fans. The balance in the size
of the openings is important to regulating the air flow.

73's   From   Tony

   


>  
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[dave.wilburn]

I think another important point is the ambient temperature
calibration.  If that is off (the K3 thinks 30c is 15c) the fans may
not come in when they should.

Dave Wilburn
NM4M

K2ZLS wrote:

> Thanks to Brendan and all the responders:
>
>   I have received several answers similar to yours regarding the heat
> sink effect.   But,  I already knew that.  The reason I'm bringing this
> up is that the concern for "hot spots" is already there.  After running
> the K3 hard, try powering down, remove power and the top cover.  Feel
> around the front side and you will notice the warmth of the display,  
> the other boards and the KRX3 box, which has NO ventilation inside and
> is a heat sink by itself.  If you examine the air flow you can't help
> but see that the air movement DOESN'T GET to these areas. It's
> concentrated in the area around the AMP enclosure.  That's my point.  
> The K3 CAN be improved if a little more attention is paid to draining
> this heat supply more efficiently instead of accepting the rise in heat
> as a GOOD thing.  I think improving the ventilation is the key here and
> maybe you are right,  my idea of cross ventilation may not be the best
> thing.  Maybe, instead of drawing ALL cooling air from the top opening,  
> a side vent is installed to provide an additional source of cooling air
> that will find its own way to the output fans. The balance in the size
> of the openings is important to regulating the air flow.
>
> 73's   From   Tony
>
>    
>
>
>>  
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... [show rest of quote]

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[Ken Kopp-3]

Sounds like you're trying to improve on the design of
the designers.  Perhaps you can, but I doubt it.  No
offense is intended, BTW.  

Frankly, I think the radio runs pretty cool, considering
what's in the box.  It's been running all day and the front
panel temp is 32C and the room is 67F.  Like Ron, I'm
glad to see the warmth  ... for several reasons.  IMO, nothin's
broke or needs fixed.

About  the fans ... I'm a 100W 20 WPM type for the most
part.  My fans rarely run.  

73! Ken Kopp - K0PP
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[Barry Simpson]

An interesting post Tony. I have exactly the same issues with the right side
panel heating up with a typical front panel temperature reaching 43C. This
has only happened since installation of the second receiver which virtually
cuts off the airflow inside. The front panel typically runs hotter than the
PA.

I have already gone down the road of cutting six vertical slots in the right
hand side panel to assist with air flow. Regrettably it makes no difference
to the temperature. The only way to lower the temperature significantly is
to have the fans on permanently. This way there is some air sucked through
the vents in the panel and I can drop the temp down to the low 30's.

Given that the high temperature of the side panel does not appear to have
any detrimental effect I have now given up worrying about it.

73

Barry  VK2BJ

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of K2ZLS
Sent: 14 May 2009 21:06
To: [hidden email]
Subject: [Elecraft] K3 COOLING VENTS

Hi,

     There have been enough posts here about the temperature inside the
K3 to start me thinking.   Mine also gets very WARM on the right side by
U12 and U13.  You all know how "boxed in"  the Front side of the K3 has
become and now we are looking at additional features being added to the
inside of the box. The way the cooling fan is now, there is little or no
circulation of air in the front side of the K3.  Another poster wanted
to add bigger fans but, you know, that will not solve the heat problem
because the air can't get to where it needs to go.  I would like to
"CROSS VENTILATE" the front area by adding cooling vents, similar to the
configuration of the speaker vents,  to both side panels.  There does
not seem to be any worry about RF leakage at the rear vents where the
AMP is and the side vents can be fashioned the same way.  I know that
Wayne feels that the cooling is adequate but,  I think this would be a
worthy modification at this point, if only to let the HOT AIR ...OUT.

If someone knows how to punch out this configuration, I would gladly
supply the panels and pay any costs involved.

73's  and  Thanks.

Tony      K2ZLS at OPTONLINE  dot  NET
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[Ken Kopp-3]

I wonder what's different ... if anything ... in our K3's?

Mine's been on about 15 hours and the FP temperature
is 33C.  A digital thermometer on the desk beside the
radio shows the ambient temperature is 21C.

I -do- have the 2nd receiver installed. and in operation.

I haven't transmitted other than an occasional CW ID
on 6M.  The PA TEMP shows 29C.

These temps seem lower than what some are reporting.
As in my last posting, the fans rarely turn on.

73! Ken Kopp - K0PP
      [hidden email]
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[Brendan Minish]

I think there are a few points that still need to be considered here

How hot are the hot spots? 10 to 20 degrees C above ambient or 50+
degrees above ambient temp. 10 to 20 degrees above ambient temp is
nothing to worry about.

The dominant heat source is the voltage regulators, adding the Sub RX
increases the load on the voltage regulators so they in turn run a bit
hotter. The primary cooling mechanism for these voltage regulators is by
thermal conduction to the side panel, not by convection. Keep the
side-panel cooler and the regulator area will be cooler too.
If this is a route you really want to go down then I would propose
installing an external finned heatsink on the outside of the K3 in the
vicinity of the regulators, reuse the screw holes for the regulator to
mount the heatsink, be sure to clean down to metal on the side-panel
under the heatskink and use a thermal grease. This will be a lot more
efficient than chopping extra holes in the case and if you want to sell
your K3 someday all you will need to order is a new side-panel      
 
The Sidepanel is in reasonable thermal contact with the rest of the
chassis, you may also find that the radio runs cooler if you set the
fans on low so they are running all the time at low speed.
You could also use a slowly turning external fan to blow air up at the
right underside and along the right side of the radio.

In my opinion the thermal design of the K3 is just fine the way it is,
all components are operating within their thermal specifications by a
very wide margin and internal temperature in the vicinity of the ref
oscillator stabilises quickly after power on.

The K3 runs much cooler than many other radios I have used, it's just
that with many other radios the inner chassis is not in good thermal
contact with outer chassis so you remain unaware of how hot things are
getting around the voltage regulators etc.

Warm is fine, too hot to touch is probably not..


--
73
Brendan EI6IZ

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[drewko]

On Fri, 15 May 2009 02:58:42 +0000, Barry  VK2BJ wrote:

>
>I have already gone down the road of cutting six vertical slots in the right
>hand side panel to assist with air flow.
>

I would sooner mount a peltier junction on the side panel. But even
sooner than that I would just crank up the A/C...  

"I'm an air-conditioned gypsy
that's my solution..."  -- The Who

73,
Drew
AF2Z

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[Mel]

An old thought.  When trying to get heat out, one usually gets dirt, bugs, etc. in.  I like cranking up the AC and leave well enough alone.  Of course there is always the freon bath, not.

Mel, K6KBE

--- On Fri, 5/15/09, drewko <[hidden email]> wrote:

From: drewko <[hidden email]>
Subject: Re: [Elecraft] K3 COOLING VENTS
To: [hidden email]
Date: Friday, May 15, 2009, 1:22 PM

On Fri, 15 May 2009 02:58:42 +0000, Barry  VK2BJ wrote:

>
>I have already gone down the road of cutting six vertical slots in the right
>hand side panel to assist with air flow.
>

I would sooner mount a peltier junction on the side panel. But even
sooner than that I would just crank up the A/C... 

"I'm an air-conditioned gypsy
that's my solution..."  -- The Who

73,
Drew
AF2Z

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[Tony Scesny]

Hi Barry,

     Thank you for your interest.  I have received many replies both
good and bad.  Bad,  because many think I have some kind of heating
PROBLEM with the K3.  Not so.  My only intent is to try lower the FP
temp like you.  Here's what I found.   Your slots are a GOOD start but
not enough.  No amount of fan speed will bring that temp down.  WHY?  
Well you only have to take the top cover off and try to follow where the
air will go.  You can't , you say,  because the front compartment is
isolated from the rear compartment by the panel that goes across the
middle.  That's my point.  The middle panel will also need vents so the
air can get back to where the fan is trying to suck it out.  There is a
tremendous source of fresh air on top of the PA and that's a GOOD thing
but, it doesn't allow for a very good draw for air trapped in the front
compartment.  The fan speed seems more controlled by the PA sensor than
the FP sensor.  That's a good thing because we've seen that the fan has
NO effect on FP temp.
   
Here's what I would like to try.  I would open up the side panel above
U12 and U13  with slots designed similar to that of the speaker.  This
pattern is already proven and in use over the top panel and speaker.  
Open up the bottom panel, just behind the front panel, with a slot
similar to those in the rear bottom panel.  No big deviation here.  Just
gives air better access to cool the bottom of the main board.  Open up
the center internal partition with the same kind of elongated slots like
the bottom panel.  Now,  what you have is the side and bottom slots
providing cool air to the front enclosure.  The middle partition slots
provide a way for the air to be drawn to the rear PA enclosure, to be
sucked out by the fan.   I don't think this is such a radical change
that goes against existing design and I'm sure it will be an improvement.

     The other driving factor here, that NOBODY seems to take
seriously,  is the heating effect on the computer chips and DSP
processor. They could use heat sinks, but space limitations may be a
problem.  My background is computers and I know that  HEAT is their
WORST nightmare. I'm sure you have seen the latest memory sticks with
elaborate heat sinks.  That's partly due to the high frequency and heat
generation affecting the timing latency.  But, the idea applies to ALL
these device types. You have read all the responses regarding the
exploits of all the heat extremes that have been posted saying that
nothing bad has happened.  But I ask,  how many unexplained K3 events
requiring restarts and FW reloads can be attributed to this.  I can't
say but, the potential is there, as long as the heat keeps building up.

 So again, let me say that there is NOT any PROBLEM with K3.   Only that
it could,  and  will get better.

73's  cheers and keep the shinny side up.        From  Tony   K2ZLS

Barry Simpson wrote:

> An interesting post Tony. I have exactly the same issues with the right side
> panel heating up with a typical front panel temperature reaching 43C. This
> has only happened since installation of the second receiver which virtually
> cuts off the airflow inside. The front panel typically runs hotter than the
> PA.
>
> I have already gone down the road of cutting six vertical slots in the right
> hand side panel to assist with air flow. Regrettably it makes no difference
> to the temperature. The only way to lower the temperature significantly is
> to have the fans on permanently. This way there is some air sucked through
> the vents in the panel and I can drop the temp down to the low 30's.
>
> Given that the high temperature of the side panel does not appear to have
> any detrimental effect I have now given up worrying about it.
>
> 73
>
> Barry  VK2BJ
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of K2ZLS
> Sent: 14 May 2009 21:06
> To: [hidden email]
> Subject: [Elecraft] K3 COOLING VENTS
>
> Hi,
>
>      There have been enough posts here about the temperature inside the
> K3 to start me thinking.   Mine also gets very WARM on the right side by
> U12 and U13.  You all know how "boxed in"  the Front side of the K3 has
> become and now we are looking at additional features being added to the
> inside of the box. The way the cooling fan is now, there is little or no
> circulation of air in the front side of the K3.  Another poster wanted
> to add bigger fans but, you know, that will not solve the heat problem
> because the air can't get to where it needs to go.  I would like to
> "CROSS VENTILATE" the front area by adding cooling vents, similar to the
> configuration of the speaker vents,  to both side panels.  There does
> not seem to be any worry about RF leakage at the rear vents where the
> AMP is and the side vents can be fashioned the same way.  I know that
> Wayne feels that the cooling is adequate but,  I think this would be a
> worthy modification at this point, if only to let the HOT AIR ...OUT.
>
> If someone knows how to punch out this configuration, I would gladly
> supply the panels and pay any costs involved.
>
> 73's  and  Thanks.
>
> Tony      K2ZLS at OPTONLINE  dot  NET
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
>  

... [show rest of quote]

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[Eric Swartz - WA6HHQ]

Hi Tony,

We've looked at the fp temp range during the design, testing and now during our ongoing relaibility testing of the K3. There is nothing out of range here and we are very comfortable with it.

It is not a reliability issue at these temps, and it certainly not causing any operational issues. We are not stressing the DSP amd FP parts nearly as much as typical PCs do.

73,

Eric  WA6HHQ
_..._
-----Original Message-----
From: K2ZLS <[hidden email]>
Date: Friday, May 15, 2009 7:13 pm
Subject: [Elecraft] K3 COOLING VENTS
To: [hidden email]

Hi Barry,

     Thank you for your interest.  I have received many replies both
good and bad.  Bad,  because many think I have some kind of heating
PROBLEM with the K3.  Not so.  My only intent is to try lower the FP
temp like you.  Here's what I found.   Your slots are a GOOD start but
not enough.  No amount of fan speed will bring that temp down.  WHY?  
Well you only have to take the top cover off and try to follow where the
air will go.  You can't , you say,  because the front compartment is
isolated from the rear compartment by the panel that goes across the
middle.  That's my point.  The middle panel will also need vents so the
air can get back to where the fan is trying to suck it out.  There is a
tremendous source of fresh air on top of the PA and that's a GOOD thing
but, it doesn't allow for a very good draw for air trapped in the front
compartment.  The fan speed seems more controlled by the PA sensor than
the FP sensor.  That's a good thing because we've seen that the fan has
NO effect on FP temp.
   
Here's what I would like to try.  I would open up the side panel above
U12 and U13  with slots designed similar to that of the speaker.  This
pattern is already proven and in use over the top panel and speaker.  
Open up the bottom panel, just behind the front panel, with a slot
similar to those in the rear bottom panel.  No big deviation here.  Just
gives air better access to cool the bottom of the main board.  Open up
the center internal partition with the same kind of elongated slots like
the bottom panel.  Now,  what you have is the side and bottom slots
providing cool air to the front enclosure.  The middle partition slots
provide a way for the air to be drawn to the rear PA enclosure, to be
sucked out by the fan.   I don't think this is such a radical change
that goes against existing design and I'm sure it will be an improvement.

     The other driving factor here, that NOBODY seems to take
seriously,  is the heating effect on the computer chips and DSP
processor. They could use heat sinks, but space limitations may be a
problem.  My background is computers and I know that  HEAT is their
WORST nightmare. I'm sure you have seen the latest memory sticks with
elaborate heat sinks.  That's partly due to the high frequency and heat
generation affecting the timing latency.  But, the idea applies to ALL
these device types. You have read all the responses regarding the
exploits of all the heat extremes that have been posted saying that
nothing bad has happened.  But I ask,  how many unexplained K3 events
requiring restarts and FW reloads can be attributed to this.  I can't
say but, the potential is there, as long as the heat keeps building up.

 So again, let me say that there is NOT any PROBLEM with K3.   Only that
it could,  and  will get better.

73's  cheers and keep the shinny side up.        From  Tony   K2ZLS

Barry Simpson wrote:
 An interesting post Tony. I have exactly the same issues with the right side
 panel heating up with a typical front panel temperature reaching 43C. This
 has only happened since installation of the second receiver which virtually
 cuts off the airflow inside. The front panel typically runs hotter than the
 PA.

> I have already gone down the road of cutting six vertical slots in the right
 hand side panel to assist with air flow. Regrettably it makes no difference
 to the temperature. The only way to lower the temperature significantly is
 to have the fans on permanently. This way there is some air sucked through
 the vents in the panel and I can drop the temp down to the low 30's.

> Given that the high temperature of the side panel does not appear to have
 any detrimental effect I have now given up worrying about it.

> 73

> Barry  VK2BJ

> -----Original Message-----
 From: [hidden email]
 [mailto:[hidden email]] On Behalf Of K2ZLS
 Sent: 14 May 2009 21:06
 To: [hidden email]
 Subject: [Elecraft] K3 COOLING VENTS

> Hi,

>      There have been enough posts here about the temperature inside the
 K3 to start me thinking.   Mine also gets very WARM on the right side by
 U12 and U13.  You all know how "boxed in"  the Front side of the K3 has
 become and now we are looking at additional features being added to the
 inside of the box. The way the cooling fan is now, there is little or no
 circulation of air in the front side of the K3.  Another poster wanted
 to add bigger fans but, you know, that will not solve the heat problem
 because the air can't get to where it needs to go.  I would like to
 "CROSS VENTILATE" the front area by adding cooling vents, similar to the
 configuration of the speaker vents,  to both side panels.  There does
 not seem to be any worry about RF leakage at the rear vents where the
 AMP is and the side vents can be fashioned the same way.  I know that
 Wayne feels that the cooling is adequate but,  I think this would be a
 worthy modification at this point, if only to let the HOT AIR ...OUT.

> If someone knows how to punch out this configuration, I would gladly
 supply the panels and pay any costs involved.

> 73's  and  Thanks.

> Tony      K2ZLS at OPTONLINE  dot  NET
 ______________________________________________________________
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 Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>

>  
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[Eric Swartz - WA6HHQ]

Hi Tony,

We've looked at the fp temp range during the design, testing and now during our ongoing relaibility testing of the K3. There is nothing out of range here and we are very comfortable with it.

It is not a reliability issue at these temps, and it certainly not causing any operational issues. We are not stressing the DSP amd FP parts nearly as much as typical PCs do.

73,

Eric  WA6HHQ
_..._
-----Original Message-----
From: K2ZLS <[hidden email]>
Date: Friday, May 15, 2009 7:13 pm
Subject: [Elecraft] K3 COOLING VENTS
To: [hidden email]



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[Brendan Minish]

On Fri, 2009-05-15 at 19:13 -0400, K2ZLS wrote:

>      The other driving factor here, that NOBODY seems to take
> seriously,  is the heating effect on the computer chips and DSP
> processor. They could use heat sinks, but space limitations may be a
> problem.  My background is computers and I know that  HEAT is their
> WORST nightmare.

My PC consumes well over 200W of power when running hard, My graphics
subsystem another 80-100W or so when stressed. almost all of this
dissipation is confined to a few very small areas, this is a heat
problem. My i7 CPU with a big heatsink and fan on it stabilises at 57C
when working hard (~35 degrees C above ambient temp)  

My K3 with Sub consumes under 15W in receive, the front panel temp
stabilises at around 14 Degrees above ambient temp after being on a
while. this is not a heat problem, no matter how you look at it.
   

If it makes you happy, cool the case externally. the side panels are in
good thermal contact with the internal screen between the Front panel
area and the rest of the radio so this will also lower the temp in the
front panel area.

Cut slots or holes in there and you will have a new set of issues to
deal with, namely EMC issues with digital trash from the front panel
DSP / CPU areas getting back into the receiver.

--
73
Brendan EI6IZ

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[Guy, K2AV]

From: "K2ZLS" <[hidden email]>

>     The other driving factor here, that NOBODY seems to take
> seriously,  is the heating effect on the computer chips and DSP
> processor. They could use heat sinks, but space limitations may be a
> problem.  My background is computers and I know that  HEAT is their
> WORST nightmare.

"Nobody" is a pretty big word to use.  There is a real crowd of old f*rts on
this reflector that have been in computers since the beginning, and at some
point would have killed to get internal temps in heat generating components
down (I repeat, down) to the upper 30's, low 40's C.  The K3's FP reading is
an INTERNAL reading.  If 110 F is a fault temperature, then you could
destroy your K3 by leaving it out in the sun.

My PC is routinely much warmer than the K3, and a lot warmer doing antenna
design number crunching.

I take temperatures very seriously.  I just disagree that the reported FP
internal temps are anywhere near a risk. And if the FP temp sensing is in an
SM chip, then it is a contact temperature, that will be warmer than the
inside air, and even less of a risk.

Seems that if I want to buy a K3 used, I'll need to remember to explicitly
request "no non-stock holes".  What you propose would be a deal-killer for
me.

73, Guy.


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[David Woolley (E.L)]

Guy Olinger, K2AV wrote:

> an INTERNAL reading.  If 110 F is a fault temperature, then you could
> destroy your K3 by leaving it out in the sun.

That's not a valid comparison.  The sort of temperature that will cause
rapid damage is 150C for silicon semiconductors, something like 100C for
electrolytics, 75C for the 1N34 germanium point contact diodes, if it
uses them.  These temperatures are reached when the equipment is
operating at full power and the insides of the devices are much hotter
than the point at which the temperature sensor is placed.  If you leave
the equipment out in the sun, powered down, and the case temperature
reaches 45C, the inside of the semiconductor devices will also be at
45C, well below 150C.  It may be lower, because of thermal inertia.

Typical consumer equipment is designed to tolerate an air temperature of
45C whilst keeping the core temperature of internal devices well within
safety limits.  If you actually operate at that sort of temperature, the
case temperature and internal temperature will be significantly higher.

Leaving electronics exposed to the sun can, of course, result in
destroying some of the more temperature sensitive components, as case
temperatures can get a lot higher than 45C.   Having a large thermal
mass will help protect the equipment as the sun should start to go down
before the maximum temperature is reached.


--
David Woolley
"The Elecraft list is a forum for the discussion of topics related to
Elecraft products and more general topics related ham radio"
List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm>
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[Guy, K2AV]

I believe you make my point perfectly. Folks are complaining about displayed
K3 circuit board and PA heat sink temperatures (not air temp) of 35-45 C as
if they were somehow dangerous.

While individual components can exceed a measured temp spot in a device,
good engineering practice in selection of components for their individual
dissipation in working circuits will insure that the measured spot is
representative so far as safety is concerned across the circuit.

In the case of a piece of ham gear, anything not so engineered, e.g. a
poorly designed hot spot, will be destroyed by contesters, and broadly
complained about, as so well demonstrated over the decades.  Aptos is well
aware of PVRC and NCCC gossip.  : >)

Blown solid state finals in HF rigs have been a common complaint in said
decades-long gossip stream.  By height times width times depth volume the
KPA3 is mostly heat sink and a third of the K3 back panel space is fan mount
to pull air across said mostly heat sink KPA3. The K3 is a very conservative
design, heat-wise.

73, Guy

From: "David Woolley (E.L)" <[hidden email]>

>> an INTERNAL reading.  If 110 F is a fault temperature, then you could
>> destroy your K3 by leaving it out in the sun.
>
> That's not a valid comparison.  The sort of temperature that will cause
> rapid damage is 150C for silicon semiconductors, something like 100C for
> electrolytics, 75C for the 1N34 germanium point contact diodes, if it
> uses them.  These temperatures are reached when the equipment is
> operating at full power and the insides of the devices are much hotter
> than the point at which the temperature sensor is placed.  If you leave
> the equipment out in the sun, powered down, and the case temperature
> reaches 45C, the inside of the semiconductor devices will also be at
> 45C, well below 150C.  It may be lower, because of thermal inertia.
>
> Typical consumer equipment is designed to tolerate an air temperature of
> 45C whilst keeping the core temperature of internal devices well within
> safety limits.  If you actually operate at that sort of temperature, the
> case temperature and internal temperature will be significantly higher.
>
> Leaving electronics exposed to the sun can, of course, result in
> destroying some of the more temperature sensitive components, as case
> temperatures can get a lot higher than 45C.   Having a large thermal
> mass will help protect the equipment as the sun should start to go down
> before the maximum temperature is reached.

... [show rest of quote]

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[AC7AC]

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