Re: [Elecraft] K2 Power Level
After posting the question I found this on page 102 of the manual: RTTY/Data Operation Since some RTTY/Data mode duty cycles approach 100%, you should reduce power to about 5 watts or avoid transmitting at 10 watts for longer than 1-2 minutes at a time. (Power levels above 10 watts are not recommend.) For me, 5 watts with FT8 is more than adequate. Aaron K5ATG __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K2 Power Level
Of course what the material is matters a lot. A 60C piece of wood or plastic (not good heatsink materials) will feel warm whereas a hunk of aluminum will feel quite hot due to its much higher thermal conductivity and heat capacity. On Monday, August 16, 2021, 02:40:37 PM MDT, Lyn Norstad wrote: Interesting point, Don. I never thought of the "finger test" for that purpose, but the "Threshold of Pain" is normally considered to be 42C (or 107F). My KPA500 reaches that temp after about 8 seconds of 40 meter carrier with a drive level of 18 watts and an output level of about 350 watts. (Normal 'power off temp' runs about 37C). The average person can touch a 140F surface for 5 seconds without sustaining irreversible burn damage. Such a simple, basic thing to know ... but who does? 73 Lyn, W0LEN -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don Wilhelm Sent: Monday, August 16, 2021 1:55 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 Power Level All, I was reminded that I should have added that CW and SSB are low duty cycle modes while FT8 and several other data modes are high duty cycle and will produce more heat. The 'finger test' I mentioned is suitable for any mode. 73, Don W3FPR -- Aaron, I cannot give you a specific answer, but go by the heat. I would suggest you first try 5 watts, and operate at that level for a while (I suggest 10 minutes). Then check the heatsink temperature - if you can hold your fingers on it for longer than 5 minutes, then all is well. Increase the power by about 3 watts and try again. When the heat gets too much to comfortably hold your fingers on the heatsink (next to the PA transistors), then you have exceeded the maximum power which you should use for transmit. The generalized answer is that you should consider those modes as continuous duty and use 1/2 the normal full power output, but I suggest doing the test I referred to as a specific power limit for your particular K2. 73, Don W3FPR On 8/13/2021 3:38 PM, Aaron K5ATG wrote: > What is the recommended highest power level for a QRP Elecraft K2 to > operate on digital modes like FT8, JT65 etc, without blowing the PA's? > __ 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 Message delivered to l...@lnainc.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 Message delivered to louand...@yahoo.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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K2 Power Level
Interesting point, Don. I never thought of the "finger test" for that purpose, but the "Threshold of Pain" is normally considered to be 42C (or 107F). My KPA500 reaches that temp after about 8 seconds of 40 meter carrier with a drive level of 18 watts and an output level of about 350 watts. (Normal 'power off temp' runs about 37C). The average person can touch a 140F surface for 5 seconds without sustaining irreversible burn damage. Such a simple, basic thing to know ... but who does? 73 Lyn, W0LEN -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don Wilhelm Sent: Monday, August 16, 2021 1:55 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] K2 Power Level All, I was reminded that I should have added that CW and SSB are low duty cycle modes while FT8 and several other data modes are high duty cycle and will produce more heat. The 'finger test' I mentioned is suitable for any mode. 73, Don W3FPR -- Aaron, I cannot give you a specific answer, but go by the heat. I would suggest you first try 5 watts, and operate at that level for a while (I suggest 10 minutes). Then check the heatsink temperature - if you can hold your fingers on it for longer than 5 minutes, then all is well. Increase the power by about 3 watts and try again. When the heat gets too much to comfortably hold your fingers on the heatsink (next to the PA transistors), then you have exceeded the maximum power which you should use for transmit. The generalized answer is that you should consider those modes as continuous duty and use 1/2 the normal full power output, but I suggest doing the test I referred to as a specific power limit for your particular K2. 73, Don W3FPR On 8/13/2021 3:38 PM, Aaron K5ATG wrote: > What is the recommended highest power level for a QRP Elecraft K2 to > operate on digital modes like FT8, JT65 etc, without blowing the PA's? > __ 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 Message delivered to l...@lnainc.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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K2 Power Level
All, I was reminded that I should have added that CW and SSB are low duty cycle modes while FT8 and several other data modes are high duty cycle and will produce more heat. The 'finger test' I mentioned is suitable for any mode. 73, Don W3FPR -- Aaron, I cannot give you a specific answer, but go by the heat. I would suggest you first try 5 watts, and operate at that level for a while (I suggest 10 minutes). Then check the heatsink temperature - if you can hold your fingers on it for longer than 5 minutes, then all is well. Increase the power by about 3 watts and try again. When the heat gets too much to comfortably hold your fingers on the heatsink (next to the PA transistors), then you have exceeded the maximum power which you should use for transmit. The generalized answer is that you should consider those modes as continuous duty and use 1/2 the normal full power output, but I suggest doing the test I referred to as a specific power limit for your particular K2. 73, Don W3FPR On 8/13/2021 3:38 PM, Aaron K5ATG wrote: What is the recommended highest power level for a QRP Elecraft K2 to operate on digital modes like FT8, JT65 etc, without blowing the PA's? __ 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] K2 Power Level
Aaron, I cannot give you a specific answer, but go by the heat. I would suggest you first try 5 watts, and operate at that level for a while (I suggest 10 minutes). Then check the heatsink temperature - if you can hold your fingers on it for longer than 5 minutes, then all is well. Increase the power by about 3 watts and try again. When the heat gets too much to comfortably hold your fingers on the heatsink (next to the PA transistors), then you have exceeded the maximum power which you should use for transmit. The generalized answer is that you should consider those modes as continuous duty and use 1/2 the normal full power output, but I suggest doing the test I referred to as a specific power limit for your particular K2. 73, Don W3FPR On 8/13/2021 3:38 PM, Aaron K5ATG wrote: What is the recommended highest power level for a QRP Elecraft K2 to operate on digital modes like FT8, JT65 etc, without blowing the PA's? __ 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 Message delivered to arch...@mail-archive.com
