[Elecraft] K3 COOLING VENTS

Eric Swartz - WA6HHQ, Elecraft eric at elecraft.com
Fri May 15 21:29:00 EDT 2009 

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 <k2zls at optonline.net>
Date: Friday, May 15, 2009 7:13 pm
Subject: [Elecraft] K3 COOLING VENTS
To: ELECRAFT at mailman.qth.net

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: elecraft-bounces at mailman.qth.net
 [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of K2ZLS
 Sent: 14 May 2009 21:06
 To: ELECRAFT at mailman.qth.net
 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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