Cooling fans
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Hello all.
I'm getting my K2/100 ready for sweeps and have decided to add some aux cooling. I have a couple of 3" computer case fans and was wondering from those who've done the same about placement and whether blow the air onto the heatsink or suck it through. Thanks for your input. R. Kevin Stover AC0H K2/100 # 4684. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Kevin -
It has been my experience that blowing air onto a heat sink is usually more effective than "sucking" air. If the heat sink is carefully shrouded and the incoming airflow is properly controlled, then either method is supposed to be effective. However, for uncontrolled or casual situations where you are simply placing the fan on or near the heat sink to be cooled, blowing (hopefully cooler) air onto the heat sink fins is much more effective in lowering the temperature of the heat sink. The reason for this is that the outlet of a fan has a well defined airflow that can be easily directed to where it is needed, whereas the inlet side of the fan will gather air from wherever it can, some or even most of which may not be from the heat sink. Good luck in the contest. - Jim, KL7CC R. Kevin Stover wrote: >Hello all. > >I'm getting my K2/100 ready for sweeps and have decided to add some aux > > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by ac0h
Kevin,
The easiest solution is to simply lay the fan (horizontally) across the heat sink fins. Suck the hot air away from the heat sink, that way it works in tandem with the internal fan rather than fighting the internal fan airstream. 73, Don W3FPR > -----Original Message----- > > I'm getting my K2/100 ready for sweeps and have decided to add some aux > cooling. > I have a couple of 3" computer case fans and was wondering from those > who've done the same about placement and whether blow the air onto the > heatsink or suck it through. > > Thanks for your input. > > R. Kevin Stover > AC0H > K2/100 # 4684. > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Kevin -
Don may be correct in this case. I have not seen a K2/100, and if indeed air is already being directed through the heat sink, then you certainly don't want to set up an opposing airflow. Does the K2/100 heat sink have holes? How does the air flow from the internal fan reach the heat sink? My example, in my last message, is for the general case where there is little or no air directed to the external fins of the heat sink. My K2 is the basic version, no amplifier included. The photo of a K2/100 on the Elecraft main page does not show how the air from the internal fan is routed, and the internal photo of a "folded out" K2/100 is not much more help. I can see the fan in the photo, but that doesn't tell me much. - Jim, KL7CC Don Wilhelm wrote: >Kevin, > >The easiest solution is to simply lay the fan (horizontally) across the heat >sink fins. Suck the hot air away from the heat sink, that way it works in >tandem with the internal fan rather than fighting the internal fan >airstream. > >73, >Don W3FPR > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Don Wilhelm-3
Also sure you don't have anything blocking the fins at the *front* of the
K2. The air blown in the back by the little fan comes out between the fins where they reach the plate at the front of the KPA100. I've found that a lot of people don't realize the gaps are there to let the air escape. For what it's worth, I helped do the thermal testing of John's PLL temperature compensation mod (that's now built into current K2's). To do that I "hammered" my K2/100 with a great many high-duty-cycle transmit periods into a large dummy load while monitoring the internal temperature. Many times the internal air temperature got up to 50C or 60C and the KPA100 heat sink was too hot to leave my hand on it very long. Absolutely no deleterious effects were noted then or later. (Still have the same finals too <G>). That rig is designed with a large margin of safety. Ron AC7AC -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Don Wilhelm Sent: Saturday, October 29, 2005 12:19 PM To: R. Kevin Stover; Elecraft mailing list Subject: RE: [Elecraft] Cooling fans Kevin, The easiest solution is to simply lay the fan (horizontally) across the heat sink fins. Suck the hot air away from the heat sink, that way it works in tandem with the internal fan rather than fighting the internal fan airstream. 73, Don W3FPR > -----Original Message----- > > I'm getting my K2/100 ready for sweeps and have decided to add some > aux cooling. I have a couple of 3" computer case fans and was > wondering from those who've done the same about placement and whether > blow the air onto the heatsink or suck it through. > > Thanks for your input. > > R. Kevin Stover > AC0H > K2/100 # 4684. > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by ac0h
Kevin;
For some of my K2 power tests, I've placed a single 12V fan on the heat sink with 6-32 screws through the fan mounting holes to hold the fan about an inch above the heat sink. The fan blows air down onto the top of the heat sink. With that combination, I can run key down full power for a half-hour without excessive heating on the output transistors. -John KI6WX > Hello all. > > I'm getting my K2/100 ready for sweeps and have decided to add some aux > cooling. > I have a couple of 3" computer case fans and was wondering from those > who've done the same about placement and whether blow the air onto the > heatsink or suck it through. > > Thanks for your input. > > R. Kevin Stover > AC0H > K2/100 # 4684. > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Don Wilhelm-3
Ten-Tec has a very nice model 310 cooling fan for the Orion,Omni,Corsair series radios, that fits very nicely on the top of the K2/100, hangs a little bit off the rear, and if you use the tilt bail on the K2, you can use a rubber band to temp hold it on, have used it this way many times, works well 73 de K7ZUM Ken in Gres"HAM" Ore > Kevin, > > The easiest solution is to simply lay the fan (horizontally) across the heat > sink fins. Suck the hot air away from the heat sink, that way it works in > tandem with the internal fan rather than fighting the internal fan > airstream. > > 73, > Don W3FPR > > > -----Original Message----- > > > > I'm getting my K2/100 ready for sweeps and have decided to add some aux > > cooling. > > I have a couple of 3" computer case fans and was wondering from those > > who've done the same about placement and whether blow the air onto the > > heatsink or suck it through. > > > > Thanks for your input. > > > > R. Kevin Stover > > AC0H > > K2/100 # 4684. > > > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Don Wilhelm-3
G'day,
| sink fins. Suck the hot air away from the heat sink, that way it works in | tandem with the internal fan rather than fighting the internal fan | airstream. The air stream from the internal fan flows into the K2 under the KPA100 heatsink and emerges from the front. That way it keeps much of the heat out of the box. I have used a 3 inch fan sitting on the heatsink near the front propped up at 45 degrees and blowing to onto the area where the PA's are fitted underneath. When I was doing some long run (12 hour) QRSS tests at 40W output the heatsink ran cool and the KPA fan didn't even come on. Regards, Mike VP8NO _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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> -----Original Message-----
> > The air stream from the internal fan flows into the K2 under the KPA100 > heatsink and emerges from the front. That way it keeps much of the heat > out of the box. > That is why I recommend pulling the air upward from the heat sink - so it will help pull the air from inside the KPA100 as well - in the same direction as the internal fan moves the air. The ideal in my opinion is to have just enough external fan that the amount of time the internal fan runs is substantially reduced, but will still run with extended transmit periods (like RTTY or PSK31 operation). Doing things that way, it is mandatory that I not buck the normal air flow of the internal fan. For purposes of cooling a heat sink, it is just as effective to pull the hot air away from it then to concentrate an air stream to blow onto it. As an added benefit, it also pulls away any dust that may be in the air rather than causing it to load up on the heat sink and reduce the cooling effectiveness. A 12 volt auxiliary fan can be slowed down to about half speed by the addition of a series resistor, and will likely stay in place with no fasteners unless you have the KPA100 in a vibration prone environment. A slower fan will be much more quiet than one running at high speed and will be quite effective. The heat sink may get quite warm to the touch but it should not be so hot that you cannot hold your hand on it. 73, Don W3FPR _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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On Saturday 29 October 2005 23:30, Don Wilhelm wrote:
> That is why I recommend pulling the air upward from the heat sink - so it > will help pull the air from inside the KPA100 as well - in the same > direction as the internal fan moves the air. I had a dramatic demonstration of how important it is to allow heated material to rise. My general contractor in my bathroom renovation mistook the pressure release safety valve in an oil filled towel warmer (don't ask, my wife Donna wanted it) at the top for the location to install the heating element. It heated the top corner hotter than safe and the rest of the towel warmer was stone cold after hours. I didn't expect to have to intervene in their work, but when the towel warmer was clearly not working, I became involved. "Heat Rises", I said. Putting the element at the bottom and restoring the safety valve had the whole towel warmer comfortably warm very quickly. Conduction of heat is nothing compared to its rising. Ian, G4ICV, AB2GR, K2 #4962 -- _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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