K3 cooling fan cycling
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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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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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 <[hidden email]> 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:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Paul Kirley
> 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:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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