KX3 WSPR Thermo Stressing?
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I am using my KX3 as a WSPR beacon at 500mw with a Arduino based controller which provides GPS time sync, WSPR data, and audio. Currently I am running mono band at 1 two minute transmit cycle per 10 minute time block. Now I want to add KX3 band switching to my controller and increase my T/R duty cycle. Watching the PA.I current I see that my current 2 minute ON 8 minute OFF cycle shows a 30c ON – 46c OFF temp range. Running a 2 minute ON 2 minute OFF cycle shows a stabilized 36c – 49c range after about 5 ON/OFF cycles, and running continuous transmit cycles stabilizes at 48c – 53c after 6 cycles. So based on these 3 duty cycles I see a 16c, 13c, and a 5c temperature rise. The 2 on/8 off has the lowest max temp but the widest temp range, the continuous transmit has the highest max temp but the lowest range. My plan would be to have my controller switch the KX3 through 5 bands transmitting the 1 minute 53 seconds on a band and switching to the next band during the 7 second opening.
I have done extended temperature calibration with the XG50 so frequency stability should not be a issue. My question is, 53c (127f) is hot, are there any thermo stress issues to the PA or the KX3 in general with running any of these three duty cycles? Obviously I don’t want to damage my KX3. Tnx George WD0AKZ --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ 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 Message delivered to [hidden email] |
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George,
Actually 53 degC is not that hot. Look at the specs for semiconductors and you will find that is only a medium temperature. Actually at 500mW, it is unlikely that the KX3 will be damaged by even a continuous key-down. If you are operating it outdoors, you should keep it out of direct sun. If it concerns you, I would suggest adding one of the aftermarket heatsinks. 73, Don W3FPR On 9/9/2018 12:11 PM, George Pasek wrote: > I am using my KX3 as a WSPR beacon at 500mw with a Arduino based controller which provides GPS time sync, WSPR data, and audio. Currently I am running mono band at 1 two minute transmit cycle per 10 minute time block. Now I want to add KX3 band switching to my controller and increase my T/R duty cycle. Watching the PA.I current I see that my current 2 minute ON 8 minute OFF cycle shows a 30c ON – 46c OFF temp range. Running a 2 minute ON 2 minute OFF cycle shows a stabilized 36c – 49c range after about 5 ON/OFF cycles, and running continuous transmit cycles stabilizes at 48c – 53c after 6 cycles. So based on these 3 duty cycles I see a 16c, 13c, and a 5c temperature rise. The 2 on/8 off has the lowest max temp but the widest temp range, the continuous transmit has the highest max temp but the lowest range. My plan would be to have my controller switch the KX3 through 5 bands transmitting the 1 minute 53 seconds on a band and switching to the next band during the 7 second opening. > > I have done extended temperature calibration with the XG50 so frequency stability should not be a issue. > > My question is, 53c (127f) is hot, are there any thermo stress issues to the PA or the KX3 in general with running any of these three duty cycles? Obviously I don’t want to damage my KX3. ______________________________________________________________ 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 Message delivered to [hidden email] |
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Thanks for your reply Don.
I read the High Temp Limit is set for 60c so I figure I was not dangerously high but just wanted to check if there might be a mechanical preference between the shorter duty cycle with the lower temp but larger temp swing causing more of a expansion contraction issue over time or the higher duty cycle with higher temp but not near as much heating cooling. I know that on some devices the thermo stressing of components due to repeated heating cooling cycles is a issue. This will probably be in continuous use for a while so my concern is the long term effects. I will keep a watch on the temp and maybe add the heatsink as you suggested. tnx George WD0AKZ -----Original Message----- From: Don Wilhelm Sent: Sunday, September 09, 2018 11:30 AM To: George Pasek ; [hidden email] Subject: Re: [Elecraft] KX3 WSPR Thermo Stressing? George, Actually 53 degC is not that hot. Look at the specs for semiconductors and you will find that is only a medium temperature. Actually at 500mW, it is unlikely that the KX3 will be damaged by even a continuous key-down. If you are operating it outdoors, you should keep it out of direct sun. If it concerns you, I would suggest adding one of the aftermarket heatsinks. 73, Don W3FPR On 9/9/2018 12:11 PM, George Pasek wrote: > I am using my KX3 as a WSPR beacon at 500mw with a Arduino based > controller which provides GPS time sync, WSPR data, and audio. Currently > I am running mono band at 1 two minute transmit cycle per 10 minute time > block. Now I want to add KX3 band switching to my controller and increase > my T/R duty cycle. Watching the PA.I current I see that my current 2 > minute ON 8 minute OFF cycle shows a 30c ON – 46c OFF temp range. Running > a 2 minute ON 2 minute OFF cycle shows a stabilized 36c – 49c range after > about 5 ON/OFF cycles, and running continuous transmit cycles stabilizes > at 48c – 53c after 6 cycles. So based on these 3 duty cycles I see a 16c, > 13c, and a 5c temperature rise. The 2 on/8 off has the lowest max temp > but the widest temp range, the continuous transmit has the highest max > temp but the lowest range. My plan would be to have my controller switch > the KX3 through 5 bands transmitting the 1 minute 53 seconds on a band and > switching to the next band during the 7 second opening. > > I have done extended temperature calibration with the XG50 so frequency > stability should not be a issue. > > My question is, 53c (127f) is hot, are there any thermo stress issues to > the PA or the KX3 in general with running any of these three duty cycles? > Obviously I don’t want to damage my KX3. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ______________________________________________________________ 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 Message delivered to [hidden email] |
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You can always add a small PC type fan that sits on the desk and blows on the
KX3 heat sink. I will just add an extra margin of comfort. -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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 Message delivered to [hidden email] |
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