[Elecraft] K3 cooling fan cycling
The fans that cool the K3's 100-watt amplifier are thermostatically controlled. All thermostats have a temperature spread so that they do not cycle on and off constantly; for example, a thermostat might be set to turn on a cooling fan at 38 and off at 35. I would like to suggest that consideration be given to expanding the K3's spread between turn-on and turn-off temperatures to reduce fan cycling. This might be accomplished by allowing the operator to choose from a range of spreads (say, 1 degree to 5 degrees) in the Configuration menu. Presumably, the spread would adjust the turn-on temperature upward rather than adjusting the turn-off temperature downward, as the turn-off temperature should not be less than the ambient temperature. Those who are bothered by fan cycling could then choose a larger spread to reduce the problem. 73, Paul W8TM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 cooling fan cycling
The fan speeds are designed to minimize heat-related stress to the transistors. Personally I like not having to worry whether I have toasted my final transistors because I may have inadvertently changed some option for designer fan noise levels. Transmitting transistors are finicky, do NOT tolerate heat well, which is why Wayne Co. have gone so oversize on the cooling fins. They also have a calculated heat transfer function in mind. If cycling bothers you try setting CONFIG:KPA3 to FAN1 or FAN2. If you are operating SSB, that may remove most cycling. This adjustment sets the MINIMUM fan speed. NOR is fan off until called for. 73, Guy. On Wed, Apr 13, 2011 at 10:48 AM, Paul Kirley pkir...@fuse.net wrote: The fans that cool the K3's 100-watt amplifier are thermostatically controlled. All thermostats have a temperature spread so that they do not cycle on and off constantly; for example, a thermostat might be set to turn on a cooling fan at 38 and off at 35. I would like to suggest that consideration be given to expanding the K3's spread between turn-on and turn-off temperatures to reduce fan cycling. This might be accomplished by allowing the operator to choose from a range of spreads (say, 1 degree to 5 degrees) in the Configuration menu. Presumably, the spread would adjust the turn-on temperature upward rather than adjusting the turn-off temperature downward, as the turn-off temperature should not be less than the ambient temperature. Those who are bothered by fan cycling could then choose a larger spread to reduce the problem. 73, Paul W8TM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 cooling fan cycling
There are indeed two ways to eliminate fan cycling. K2AV suggests one approach, to run the fans all the time. Another approach is to run QRP all the time. Neither of those extremities appeals to me. The K3 necessarily has a temperature spread (which seems to be small) between fan-on and fan-off temperatures. I am merely suggesting that this spread be increased. If designer options are a concern, the current unadjustable spread could simply be increased to a greater, but still unadjustable, spread. As I understand it, the K3's final transistors are quite robust with regard to temperature. The thermal Achilles heel of the K3 appears to be the amplifier's multipin connector, at least according to other posts. The fans don't seem to be able to cool that connector adequately. Less fan cycling will neither solve nor exacerbate that problem. 73, Paul W8TM *** K2AV sed: If cycling bothers you try setting CONFIG:KPA3 to FAN1 or FAN2. If you are operating SSB, that may remove most cycling. This adjustment sets the MINIMUM fan speed. NOR is fan off until called for. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 cooling fan cycling
The connector of concern was fixed long ago and applied to units up to #800 or so from memory...others will correct me...:-) The K3 is used extensively in contest, DXpeditions as well as daily for for long periods by many of us and to honest I rarely notice the K3 fans are on and cycling has never bothered me. I do use headphones most of the time, especially in a contest, maybe this is why I don't notice any noise? YMMV Gary On 14 April 2011 04:10, Paul Kirley pkir...@fuse.net wrote: There are indeed two ways to eliminate fan cycling. K2AV suggests one approach, to run the fans all the time. Another approach is to run QRP all the time. Neither of those extremities appeals to me. The K3 necessarily has a temperature spread (which seems to be small) between fan-on and fan-off temperatures. I am merely suggesting that this spread be increased. If designer options are a concern, the current unadjustable spread could simply be increased to a greater, but still unadjustable, spread. As I understand it, the K3's final transistors are quite robust with regard to temperature. The thermal Achilles heel of the K3 appears to be the amplifier's multipin connector, at least according to other posts. The fans don't seem to be able to cool that connector adequately. Less fan cycling will neither solve nor exacerbate that problem. 73, Paul W8TM *** K2AV sed: If cycling bothers you try setting CONFIG:KPA3 to FAN1 or FAN2. If you are operating SSB, that may remove most cycling. This adjustment sets the MINIMUM fan speed. NOR is fan off until called for. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html -- *VK4FD - Motorhome Mobile Elecraft Equipment K3 #679, KPA-500 #018 Living the dream!!!* __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 cooling fan cycling
As I understand it, the K3's final transistors are quite robust with regard to temperature. The transistors are robust temperature-wise because they are so heavily heat-sinked and heavily fanned, and the fans dig in quickly to hold the line with small temp differences. Off the heat sink those transistors will go toast at about the same temp as other kinds. Your suggestion of spreading out the speed increases will undo the stepped fan/heatsink dissipation holding the transistors at a narrow temperature range until the fourth speed has cut in. This design is not too unlike the function of an automobile radiator thermostat which varies the speed of water circulation with the BTU heat output of the engine. The radiator thermostat actually goes from almost closed to full open in something like 15 degrees. The narrow temp range is by design, on purpose in both the K3 and automotive case. Running the fans at speed 1 or 2 all the time will postpone the transistors arriving at the narrow temp zone. Running transistors cooler won't hurt them that I know of. In the automotive case running the engine colder lowers fuel mileage. The thermal Achilles heel of the K3 appears to be the amplifier's multipin connector, at least according to other posts. The pins in question for some time now have been converted to gold plated. The issue was corrosion causing raised contact resistance which then overheated to the point of oxidizing to non-conduction. Currently shipping units and retrofitted units do not have this problem. The fans don't seem to be able to cool that connector adequately. Less fan cycling will neither solve nor exacerbate that problem. The pin corrosion issue is in no way related to the fans. Onset of the pins becoming non-conductive often happened first when the rig was stone cold. Refer to the web site's public list of modifications for further information. Dinking with the fan speed is NOT a means of addressing the old pin problem. 73, Guy 73, Paul W8TM *** K2AV sed: If cycling bothers you try setting CONFIG:KPA3 to FAN1 or FAN2. If you are operating SSB, that may remove most cycling. This adjustment sets the MINIMUM fan speed. NOR is fan off until called for. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
I don't get why it needs to generate any papers or studies or anything. Its a really easy experiment to do. Transmit into a known load and plot temperature rise vs time. Do it under the same conditions and better yet do each experiment several times and average results. Then all you have to do install the fans in the direction that generated the best performance. I'd even be willing to bet that Elecraft did just this. ~Brett (KC7OTG) On Mon, 2010-04-05 at 21:40 -0700, K6LE wrote: wish you had said In to a dummy load.. As an aside, it's amazing how many engineering papers a simple question about which way the fans should be blowing in the OP's K3 can generate! __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
I don't get why it needs to generate any papers or studies or anything. Its a really easy experiment to do. Transmit into a known load and plot temperature rise vs time. Do it under the same conditions and better yet do each experiment several times and average results. Then all you have to do install the fans in the direction that generated the best performance. I'd even be willing to bet that Elecraft did just this. That tells us **nothing** about the temperature of other components in the radio. It only tells us about the PA at the point where temperature is being sensed. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
I suspect, like any good engineering team, they did it during design. I'd be really surprised if they just did it to verify if their design was any good :-) Grant/NQ5T On Apr 6, 2010, at 4:35 AM, Brett Howard wrote: I don yet do each experiment several times and average results. Then all you have to do install the fans in the direction that generated the best performance. I'd even be willing to bet that Elecraft did just this. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Cooling of the amp aside, blowing 60C air from the amp into the other components (off and on) doesn't seem like what one would want to do! 73 de Brian/K3KO Tom W8JI wrote: I don't get why it needs to generate any papers or studies or anything. Its a really easy experiment to do. Transmit into a known load and plot temperature rise vs time. Do it under the same conditions and better yet do each experiment several times and average results. Then all you have to do install the fans in the direction that generated the best performance. I'd even be willing to bet that Elecraft did just this. That tells us **nothing** about the temperature of other components in the radio. It only tells us about the PA at the point where temperature is being sensed. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
OH heavens, the idea to transmitting into a dead band for an hour would most assuredly be considered a violation of FCC regulations. Yes, a dummy load should always be used for any type of testing. As to fans, they either BLOW or SUCK, your choice. A fan with blades performs better sucking or evacuating a cavity while a centrifugal type blower or a fan with vanes will be better suited for pressure applications. In any event, all fans are noisy either due to tip speed of the blades or bearing noise of the motor. Convection or conduction cooling is much preferred. 73 Bob, K4TAX - Original Message - From: K6LE k...@mac.com To: Elecraft Elecraft elecraft@mailman.qth.net Sent: Monday, April 05, 2010 11:40 PM Subject: Re: [Elecraft] K3 Cooling On 4/5/2010, at 9:11 , Guy Olinger K2AV wrote: Snip As to how good the cooling is, just to see what happened, I let the K3 transmit at 100 watts for a half hour into a dead band. I wish you had said In to a dummy load.. As an aside, it's amazing how many engineering papers a simple question about which way the fans should be blowing in the OP's K3 can generate! Rick K6LE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
I dislike fan noise in my shack, one of the many reasons I love my iMac, and before I considered a K3 I made a trip to Aptos and they were kind enough to let me play with one for a bit including running the fans through their paces. Then, and now on my own K3, I find it nearly impossible to hear the first 3 speeds and the 4th speed is barely detectable. That, plus the fact the the fans rarely come on at any speed means the K3 passes my personal quiet test. Rick K6LE On 4/6/2010, at 6:22 , Bob McGraw - K4TAX wrote: Snip In any event, all fans are noisy either due to tip speed of the blades or bearing noise of the motor. Convection or conduction cooling is much preferred. 73 Bob, K4TAX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
There was some serious engineering going on there. It would have been SO easy to save some money and cut down on the fin size, and leave the cabinet room for something else. It's clear that the temperature performance was a priority in the design. 73, Guy. On Tue, Apr 6, 2010 at 10:43 AM, Rick Prather k...@mac.com wrote: I dislike fan noise in my shack, one of the many reasons I love my iMac, and before I considered a K3 I made a trip to Aptos and they were kind enough to let me play with one for a bit including running the fans through their paces. Then, and now on my own K3, I find it nearly impossible to hear the first 3 speeds and the 4th speed is barely detectable. That, plus the fact the the fans rarely come on at any speed means the K3 passes my personal quiet test. Rick K6LE On 4/6/2010, at 6:22 , Bob McGraw - K4TAX wrote: Snip In any event, all fans are noisy either due to tip speed of the blades or bearing noise of the motor. Convection or conduction cooling is much preferred. 73 Bob, K4TAX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling [ END of thread]
Ding! This thread has hit the list daily posting limit threshold for a single topic. ;-) Let's end this thread. If you wish to discuss the general topic of cooling and direction of fan air flow, please take it to direct email. 73, Eric WA6HHQ Elecraft list moderator. P.S. The cooling on the K3's PA and fan air flow is very conservatively designed and keeps it well below our design maximums. On 4/6/2010 3:17 AM, Grant Youngman wrote: I suspect, like any good engineering team, they did it during design. I'd be really surprised if they just did it to verify if their design was any good :-) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
This seems to be another one of those extremely variable things about the K3. Some folk's rigs seem to be extremely quiet and others not so much. The fans in my K3 are clearly audible at all speeds. At the highest speed it competes well with the old tower PC I use for digital modes. I've replaced the fans once with very little difference in noise. Most (but not all) of the reports of very quiet fans I've heard of were from rigs with low serial numbers. I suspect Elecraft may have used different brands of fans at different times, which might account for differences in reported noise. As for how often they come on, from an idle temperature of 26C, it takes about 1:15 of 20WPM CW at 50W into a dummy load for the fans in my K3 to kick on. 73 -- Joe KB8AP On Apr 6, 2010, at 7:43 AM, Rick Prather wrote: I dislike fan noise in my shack, one of the many reasons I love my iMac, and before I considered a K3 I made a trip to Aptos and they were kind enough to let me play with one for a bit including running the fans through their paces. Then, and now on my own K3, I find it nearly impossible to hear the first 3 speeds and the 4th speed is barely detectable. That, plus the fact the the fans rarely come on at any speed means the K3 passes my personal quiet test. Rick K6LE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 Cooling
I've seen this thread on every ham list I've read - goes on forever. I always wonder - how does the K3 know which are the intake holes in the cabinet and which are exhaust? The cool air comes in replacing the hot air, right? ;-) On tube transceivers, the finals may be oriented at the rear of the chassis near the fan, so a pulling fan will bring the cool air to the finals first, then that warmed air goes to the rest of the smaller tubes on the chassis. Reverse the air flow, the finals dont get the room temp air first, the smaller tubes on the chassis do. This -may- be important on some rigs, guess it depends. I have the Drakes setup for exhaust. K3 has these fins. I am going to take a poll with my fins and find out which ones care about the direction of the air travelling across them. ;-) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Don, In my fluid mechanics labs it became apparent that exhaust cooling is much more effective than forced cooling for situations that are similar to the K3 PA 'cage'. First is that the exhaust fan does not add to the temperature of the air, and second, the flow can be more easily controlled. The exhaust fans remove heated air from the hottest spots - who cares where the cooler makeup air comes from, it can be supplied from any vent holes in the cabinet. As humans, this is counter-intuitive because we feel cooler with air blowing onto us, but that is mainly because of evaporation cooling, not air flow. We do not usually feel cooler standing on the other side of a fan. Electronics do not have that evaporative cooling effect (unless you have poured a liquid on the electronics!), so in most cases, exhaust cooling near the heated areas does a better job. If you question the fact that a fan adds heat to the air-stream, measure the temperature on the upstream side of a fan and the downstream side. I can assure you that the downstream air is warmer - the fan provides work to move the air, so it must heat the air because of that work-force (it is not the heat of the fan motor that I am referring to, but the motor heat may be present too. One can design to contain the flow on the downstream side of the fan, but I see no air channel (pipe) in the K3 to accomplish that. With old vacuum tube designs, we often used fans to pressurize the area below the chassis and direct the flow up around the tubes with chimneys around the tubes. 73, Don W3FPR Don Rasmussen wrote: I've seen this thread on every ham list I've read - goes on forever. I always wonder - how does the K3 know which are the intake holes in the cabinet and which are exhaust? The cool air comes in replacing the hot air, right? ;-) On tube transceivers, the finals may be oriented at the rear of the chassis near the fan, so a pulling fan will bring the cool air to the finals first, then that warmed air goes to the rest of the smaller tubes on the chassis. Reverse the air flow, the finals dont get the room temp air first, the smaller tubes on the chassis do. This -may- be important on some rigs, guess it depends. I have the Drakes setup for exhaust. K3 has these fins. I am going to take a poll with my fins and find out which ones care about the direction of the air travelling across them. ;-) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 Cooling
Don (FPR type), Do you really think it matters in K3 - with micro fan motors and such a simple cage? If a K3 is setup to run TX RTTY in a controlled environment, and then repeat the test with the fan direction reversed, how much of a temperature delta would you expect? [Elecraft] K3 Cooling Don Wilhelm w3fpr at embarqmail.com Mon Apr 5 15:20:41 EDT 2010 Previous message: [Elecraft] K3 Cooling Next message: [Elecraft] sound card recommendations Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Don, In my fluid mechanics labs it became apparent that exhaust cooling is much more effective than forced cooling for situations that are similar to the K3 PA 'cage'. First is that the exhaust fan does not add to the temperature of the air, and second, the flow can be more easily controlled. The exhaust fans remove heated air from the hottest spots - who cares where the cooler makeup air comes from, it can be supplied from any vent holes in the cabinet. As humans, this is counter-intuitive because we feel cooler with air blowing onto us, but that is mainly because of evaporation cooling, not air flow. We do not usually feel cooler standing on the other side of a fan. Electronics do not have that evaporative cooling effect (unless you have poured a liquid on the electronics!), so in most cases, exhaust cooling near the heated areas does a better job. If you question the fact that a fan adds heat to the air-stream, measure the temperature on the upstream side of a fan and the downstream side. I can assure you that the downstream air is warmer - the fan provides work to move the air, so it must heat the air because of that work-force (it is not the heat of the fan motor that I am referring to, but the motor heat may be present too. One can design to contain the flow on the downstream side of the fan, but I see no air channel (pipe) in the K3 to accomplish that. With old vacuum tube designs, we often used fans to pressurize the area below the chassis and direct the flow up around the tubes with chimneys around the tubes. 73, Don W3FPR Don Rasmussen wrote: I've seen this thread on every ham list I've read - goes on forever. I always wonder - how does the K3 know which are the intake holes in the cabinet and which are exhaust? The cool air comes in replacing the hot air, right? ;-) On tube transceivers, the finals may be oriented at the rear of the chassis near the fan, so a pulling fan will bring the cool air to the finals first, then that warmed air goes to the rest of the smaller tubes on the chassis. Reverse the air flow, the finals dont get the room temp air first, the smaller tubes on the chassis do. This -may- be important on some rigs, guess it depends. I have the Drakes setup for exhaust. K3 has these fins. I am going to take a poll with my fins and find out which ones care about the direction of the air travelling across them. ;-) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Dont mean to jump in but I'd be the difference would be significant. Air flow into a low pressure area causes it to expand and thus cool down (similar to the heat exchange method used in air conditioners), and the reverse for air stuffed into a high pressure area (compresses, heats up). Also, in any air cooling system the most important item is arguably the design of the _exhaust_ port - it has to be configured in such a way as to most efficiently produce a pressure differential (which is what actually moves the air) in area of the thing you need to keep cool. This is a critical design factor in engine cooling systems in aircraft for example (interestingly enough, most of the attention is on the holes in the bottom/side/top of the cowling, not the big holes in the front). In the K3 box, it doesn't look like air getting pushed in from the back has as many clean escape areas as it would the other way around. Just eyeballing mine that is. But even if so, you still have to consider the contribution of the heat exchange situation introduced by the fan in all that too. I'd be willing to bet it'd be a noticeable difference 73, LS W5QD -- View this message in context: http://n2.nabble.com/K3-Cooling-tp4855994p4856246.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Don, I suspect it would make a big difference, especially with the SubRX installed - it would be worse with the air flow inward. In order to provide effective cooling, the air flow needs to be laminar across the heat sink. If there is turbulence, the cooling effectiveness will be reduced. By blowing air onto the heat sink, first each fin would create its own bit of turbulence as the air strikes it, and then when the air flow reaches the blockage presented by the SubRX enclosure, additional turbulence is bound to occur, and that would create backpressure for the movement of the air stream. More turbulence means less cooling. With the exhaust fans, the air will come from wherever it can within the K3 enclosure and should flow in a more laminar fashion toward the fans, and then exit at the back. Again, I believe this is counter-intuitive to our normal senses. If we were to stick a finger into the air path, it would seem like the air is cooler if it is blowing on our finger. The heat sink cooling is different than the sensation of our finger, cooling of a surface is highly dependent on a laminar flow where our 'finger test' would surmise that the turbulent flow should cool better. Because of the effects of turbulence, there is also a point of diminishing returns when increasing the air flow with faster fans. Turbulence can also be created with exhaust fans, but not as readily (per volume of air moved) as with air pumped into the assembly. I have not done any air flow studies of my K3 cooling, and I don't know to what extent Elecraft has done that during the development process, but it seems to be quite OK. The highest temperatures I have seen reported is somewhere in the vicinity of 60 to 65 deg C, and if I recall correctly, Eric has stated that there is no problem below 80 deg C. (Someone correct me on that number if my memory is not correct). 15 deg C is a lot of margin. 73, Don W3FPR Don Rasmussen wrote: Don (FPR type), Do you really think it matters in K3 - with micro fan motors and such a simple cage? If a K3 is setup to run TX RTTY in a controlled environment, and then repeat the test with the fan direction reversed, how much of a temperature delta would you expect? [Elecraft] K3 Cooling Don Wilhelm w3fpr at embarqmail.com Mon Apr 5 15:20:41 EDT 2010 Previous message: [Elecraft] K3 Cooling Next message: [Elecraft] sound card recommendations Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Don, In my fluid mechanics labs it became apparent that exhaust cooling is much more effective than forced cooling for situations that are similar to the K3 PA 'cage'. First is that the exhaust fan does not add to the temperature of the air, and second, the flow can be more easily controlled. The exhaust fans remove heated air from the hottest spots - who cares where the cooler makeup air comes from, it can be supplied from any vent holes in the cabinet. As humans, this is counter-intuitive because we feel cooler with air blowing onto us, but that is mainly because of evaporation cooling, not air flow. We do not usually feel cooler standing on the other side of a fan. Electronics do not have that evaporative cooling effect (unless you have poured a liquid on the electronics!), so in most cases, exhaust cooling near the heated areas does a better job. If you question the fact that a fan adds heat to the air-stream, measure the temperature on the upstream side of a fan and the downstream side. I can assure you that the downstream air is warmer - the fan provides work to move the air, so it must heat the air because of that work-force (it is not the heat of the fan motor that I am referring to, but the motor heat may be present too. One can design to contain the flow on the downstream side of the fan, but I see no air channel (pipe) in the K3 to accomplish that. With old vacuum tube designs, we often used fans to pressurize the area below the chassis and direct the flow up around the tubes with chimneys around the tubes. 73, Don W3FPR Don Rasmussen wrote: I've seen this thread on every ham list I've read - goes on forever. I always wonder - how does the K3 know which are the intake holes in the cabinet and which are exhaust? The cool air comes in replacing the hot air, right? ;-) On tube transceivers, the finals may be oriented at the rear of the chassis near the fan, so a pulling fan will bring the cool air to the finals first, then that warmed air goes to the rest of the smaller tubes on the chassis. Reverse the air flow, the finals dont get the room temp air first, the smaller tubes on the chassis do. This -may- be important on some rigs, guess it depends. I have the Drakes setup for exhaust. K3 has these fins. I am going to take a poll with my fins and find out which ones
Re: [Elecraft] K3 Cooling
Let me throw a few things into the mix. 1.) About compression and temperature. There isn't enough pressure to make a difference. The fan in the K3 is not running at 40 PSI, or even at 0.4 PSI. I would bet the static pressure is less than 0.1 inches of water (.0036 PSI). It takes a pretty big centrifugal blower to make .036 PSI (1 inch of water), and the heating from that pressure is negligible. 2.) We really don't want laminar flow across a heatsink. We want some turbulence so the air isn't stagnant along the fins. The AL600 and ALS1300 have deflectors that add turbulence because the fins are 6 long, straight, smooth, flat, and far from the fans. Adding deflectors to create turbulence almost doubled the cooling. I doubt this is the case with the K3. 3.) I would not blow hot air from a heatsink or high dissipation area into the more sensitive electronics, nor would I do anything the engineers at Elecraft didn't suggest or approve. Generally people designing air systems know far more about the systems than casual observers. If I wanted a cooler heatsink and was left to my own devices, I would change to a higher airflow fan of the same style. I can see all sorts of problems that might occur from reversing, and even a few from adding a blow into the case helper fan. The heatsink is probably warming the air with 150 watts of heat dissipation at times. I haven't looked at current drawn by the rest of the radio, but I doubt the other components in the radio dissipate 25 watts total. Why would I blow a 150 watt heater into a 25 watt heated area? It would make a whole lot more sense to draw the slightly heated air across the heatsink than bake the rest of the radio. 73 Tom __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
I believe that if you examine the intake slots above the PA heat sink, you will see that cool intake will come in equally across the fins, with the fins farthest from the fans getting cool air directly from above, and the portion of fins closest, though pulling warm air from parts of the fins away from the fans, pulls the air with increasing velocity as the fans are approached, cooling the heat sink near equally. That does NOT happen if the flow is reversed as the fins farthest away get the LEAST velocity with the hottest air. Flow should definitely PULL over the fins and exhaust out the back. In a minor disagreement with Don, I think that the unequal cooling is the killer issue not the fan raising the air temp blowing in. I'm not going to do it on mine (I like it working), but if someone actually reverses that and goes, I'd guess +10 to +20C in the temp and kicking in the overtemp protection. As to how good the cooling is, just to see what happened, I let the K3 transmit at 100 watts for a half hour into a dead band. It never hit 60C. I set there watching it the whole time waiting for a temp spike that never happened. It got up to the high fan speed and blew fairly warm air out the back, but stayed steady. K3 is brick on key. Something must be correctly engineered. After that was over it occurred to me that I could have fried my Astron RS35A, but that held up as well. : ) 73, Guy. On Mon, Apr 5, 2010 at 7:08 PM, Don Rasmussen wb8...@yahoo.com wrote: Don (FPR type), Do you really think it matters in K3 - with micro fan motors and such a simple cage? If a K3 is setup to run TX RTTY in a controlled environment, and then repeat the test with the fan direction reversed, how much of a temperature delta would you expect? [Elecraft] K3 Cooling Don Wilhelm w3fpr at embarqmail.com Mon Apr 5 15:20:41 EDT 2010 Previous message: [Elecraft] K3 Cooling Next message: [Elecraft] sound card recommendations Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Don, In my fluid mechanics labs it became apparent that exhaust cooling is much more effective than forced cooling for situations that are similar to the K3 PA 'cage'. First is that the exhaust fan does not add to the temperature of the air, and second, the flow can be more easily controlled. The exhaust fans remove heated air from the hottest spots - who cares where the cooler makeup air comes from, it can be supplied from any vent holes in the cabinet. As humans, this is counter-intuitive because we feel cooler with air blowing onto us, but that is mainly because of evaporation cooling, not air flow. We do not usually feel cooler standing on the other side of a fan. Electronics do not have that evaporative cooling effect (unless you have poured a liquid on the electronics!), so in most cases, exhaust cooling near the heated areas does a better job. If you question the fact that a fan adds heat to the air-stream, measure the temperature on the upstream side of a fan and the downstream side. I can assure you that the downstream air is warmer - the fan provides work to move the air, so it must heat the air because of that work-force (it is not the heat of the fan motor that I am referring to, but the motor heat may be present too. One can design to contain the flow on the downstream side of the fan, but I see no air channel (pipe) in the K3 to accomplish that. With old vacuum tube designs, we often used fans to pressurize the area below the chassis and direct the flow up around the tubes with chimneys around the tubes. 73, Don W3FPR Don Rasmussen wrote: I've seen this thread on every ham list I've read - goes on forever. I always wonder - how does the K3 know which are the intake holes in the cabinet and which are exhaust? The cool air comes in replacing the hot air, right? ;-) On tube transceivers, the finals may be oriented at the rear of the chassis near the fan, so a pulling fan will bring the cool air to the finals first, then that warmed air goes to the rest of the smaller tubes on the chassis. Reverse the air flow, the finals dont get the room temp air first, the smaller tubes on the chassis do. This -may- be important on some rigs, guess it depends. I have the Drakes setup for exhaust. K3 has these fins. I am going to take a poll with my fins and find out which ones care about the direction of the air travelling across them. ;-) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman
Re: [Elecraft] K3 Cooling
On 4/5/2010, at 9:11 , Guy Olinger K2AV wrote: Snip As to how good the cooling is, just to see what happened, I let the K3 transmit at 100 watts for a half hour into a dead band. I wish you had said In to a dummy load.. As an aside, it's amazing how many engineering papers a simple question about which way the fans should be blowing in the OP's K3 can generate! Rick K6LE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 Cooling
Hi Folks, Which way is the air flow supposed to be through the fans on the K3? Mine blows out, pulling air in from the slots in the top above the KPA3. (My K2 blows in.) The manual doesn't seem real clear on which way to install them in the K3. My K3 is nearing eight months old and doesn't seem to have a major cooling problem. But, I do some heavy RTTY contesting and I've occasionally seen the PA temp at over 60 degrees centigrade. I'm considering adding a fan on half inch stand offs from the bottom of the shelf above the radio to blow through the slots in the top of the K3. Will this disturb normal airflow around other components possibly causing them to overheat? In the past I installed an external fan on two off-shore radios and it seemed to improve cooling. I want to be sure I have the fans installed correctly and there would not be other problems before proceeding. Thanks everyone. CU in the Colorado QSO Party Sept 4th, 2010. 73, Jim, W0EM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
They are exhaust fans, blowing air out. The manual states that the fans must be oriented so that the manufacturer's label faces outward. This is correct, since the convention is that the air flows in the direction of the label on the fan. Bob NW8L On Sun, Apr 4, 2010 at 4:16 PM, Jim Harris w...@q.com wrote: Hi Folks, Which way is the air flow supposed to be through the fans on the K3? Mine blows out, pulling air in from the slots in the top above the KPA3. (My K2 blows in.) The manual doesn't seem real clear on which way to install them in the K3. My K3 is nearing eight months old and doesn't seem to have a major cooling problem. But, I do some heavy RTTY contesting and I've occasionally seen the PA temp at over 60 degrees centigrade. I'm considering adding a fan on half inch stand offs from the bottom of the shelf above the radio to blow through the slots in the top of the K3. Will this disturb normal airflow around other components possibly causing them to overheat? In the past I installed an external fan on two off-shore radios and it seemed to improve cooling. I want to be sure I have the fans installed correctly and there would not be other problems before proceeding. Thanks everyone. CU in the Colorado QSO Party Sept 4th, 2010. 73, Jim, W0EM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
At 04:31 PM 04/04/10, you wrote: They are exhaust fans, blowing air out. Finally, something on/in the K3 that sucks. John k7up __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Jim, I too wonder what the norm is for continuous RTTY use with K3. I read somewhere on the Elecraft site about higher volume fans that either could be bought, or could have been considered in the design and have thought about emailing to check on those. I suppose we would pay for that with increased noise, but the peace of mind would be nice. I'm not a contester, but an avvid RTTY rag chewer (since 1972 or so) and will often ID several times during a transmission, hi. Your 60 degrees C gives me some indication, but hope someone will chime in with other thoughts about PA temp norms on RTTY. 73, Don, WB5HAK __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Jim, Your KPA100 fan *should* exhaust air just like the K3. If yours moves air the other way, check to be certain the fan label is on the outside. 73, Don W3FPR Jim Harris wrote: Hi Folks, Which way is the air flow supposed to be through the fans on the K3? Mine blows out, pulling air in from the slots in the top above the KPA3. (My K2 blows in.) The manual doesn't seem real clear on which way to install them in the K3. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Hi Jim, The K3 fans are exhaust fans and are intended to pull hot air out of the rig. A couple years ago (June 4, 2008 if I must be precise), Eric Swartz said this in response to someone asking if 40 - 42C was too warm: We will let the heatsink get up to 85C before dropping the KPA3 off- line, that still has plenty of safety margin for the transistors. 40-42C is actually on the cool side for heavy usage. But it never hurts to keep it cool if you don't mind the added fan noise. His comment about the added fan noise was in reference to the original poster manually turning up the fan speed. I don't know if adding additional fans will help or hurt anything. My PA temp seems to plateau around 60 - 65C with high duty cycle digital modes with a shack temperature around 20C. I'm not too concerned about it, but I do keep an eye on it when running digital. 73 -- Joe KB8AP On Apr 4, 2010, at 3:16 PM, Jim Harris wrote: Hi Folks, Which way is the air flow supposed to be through the fans on the K3? Mine blows out, pulling air in from the slots in the top above the KPA3. ... I do some heavy RTTY contesting and I've occasionally seen the PA temp at over 60 degrees centigrade. I'm considering adding a fan on half inch stand offs from the bottom of the shelf above the radio to blow through the slots in the top of the K3. Will this disturb normal airflow around other components possibly causing them to overheat? ... 73, Jim, W0EM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Ken, The manual is NOT wrote to accommodate the industry accepted protocol for fans. Labels are not an accepted standard for direction of air flow. The industry standard is arrows embedded in the case of the fan indicating the direction of rotation and air movement. The manual doesn't tell me which way the air should flow. My K2 has the fan label on the outside but airflow is inward. Yes, it is assembled per the manual and verified at least twice. Perhaps I should have been more clear on my description of my conception of the instructions in the KPA3 assembly manual. CU in the Colorado QSO Party Sept 4th, 2010. 73, Jim, W0EM Date: Sun, 4 Apr 2010 17:55:54 -0500 From: k9...@socket.net To: w...@q.com Subject: Re: [Elecraft] K3 Cooling On the contrary, the ASSEMBLY manual is very clear on how they should be installed. They should blow out . . . as stated in the manual: Assembling the Fan Panel Locate the fan panel and mount the fans as shown in Figures 12 and 13 using 4-40 7/8” black flat head screws and acorn nuts. Note that the appearance of the fans in your kit may differ slightly from those shown. 1. Orient the fans with the side with the manufacturer’s label facing away from the panel. 73, Kent K9ZTV SN 21 On 4/4/2010 5:16 PM, Jim Harris wrote: Hi Folks, Which way is the air flow supposed to be through the fans on the K3? Mine blows out, pulling air in from the slots in the top above the KPA3. (My K2 blows in.) The manual doesn't seem real clear on which way to install them in the K3. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 Cooling
Don, The label on the fan of my K2 is on the outside but it pushes air inward. Verified many times including fan wiring. CU in the Colorado QSO Party Sept 4th, 2010. 73, Jim, W0EM Date: Sun, 4 Apr 2010 20:14:07 -0400 From: w3...@embarqmail.com To: w...@q.com CC: elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 Cooling Jim, Your KPA100 fan *should* exhaust air just like the K3. If yours moves air the other way, check to be certain the fan label is on the outside. 73, Don W3FPR Jim Harris wrote: Hi Folks, Which way is the air flow supposed to be through the fans on the K3? Mine blows out, pulling air in from the slots in the top above the KPA3. (My K2 blows in.) The manual doesn't seem real clear on which way to install them in the K3. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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) for...@david-woolley.me.uk 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. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
Guy, K2AV, wrote: Blown solid state finals in HF rigs have been a common complaint in said decades-long gossip stream. - It would help if we could see their plates glowing red before they failed. Many times I've set the loading on my homebrew rig finals using the color of the plates to decide max power for the duty cycle being used, and I don't recall *ever* having to replace a final tube. Unfortunately, that doesn't work for solid state. Modern rigs are like cars with power steering: you crank the knob and hope the designers did their job so well you don't have to make any judgment calls. That's been true of my K2 for the past decade. The few times they discovered something that could go wrong as more customers like me used (and sometimes abused) the rig, they fixed it with a mod post haste. I expect the same will be true of the K3 over the next decade. Ron AC7AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
From: K2ZLS k2...@optonline.net 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. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
On Fri, 15 May 2009 02:58:42 +, 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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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 drew...@verizon.net wrote: From: drewko drew...@verizon.net Subject: Re: [Elecraft] K3 COOLING VENTS To: ELECRAFT@mailman.qth.net Date: Friday, May 15, 2009, 1:22 PM On Fri, 15 May 2009 02:58:42 +, 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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 COOLING VENTS
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-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of K2ZLS Sent: 14 May 2009 21:06 To: ELECRAFT@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
Re: [Elecraft] K3 COOLING VENTS
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 k2...@optonline.net Date: Friday, May 15, 2009 7:13 pm Subject: [Elecraft] K3 COOLING VENTS To: ELECRAFT@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-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of K2ZLS Sent: 14 May 2009 21:06 To: ELECRAFT@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
Re: [Elecraft] K3 COOLING VENTS
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 k2...@optonline.net Date: Friday, May 15, 2009 7:13 pm Subject: [Elecraft] K3 COOLING VENTS To: ELECRAFT@mailman.qth.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
The reason that side feels warm is because the side itself is the heat sink for the regulators, moving the heat out of the K3 through the metal. There's absolutely no problem with the rig feeling warm. In fact, it's good. It keeps everything inside dry and stable. Ron AC7AC --- --Original Message- 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. ... I would like to CROSS VENTILATE the front area by adding cooling vents, similar to the configuration of the speaker vents, 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 COOLING VENTS
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 COOLING VENTS
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-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of K2ZLS Sent: 14 May 2009 21:06 To: ELECRAFT@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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K3 COOLING
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 elecraftcov...@rfwave.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
