K2/100 output variation
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I am sure I have seen a discussion about this one before. During an
enjoyable 160m opening to the Right Coast just before Christmas I was running a few Stateside stations and noticed a definite output power variation coming from my Acom 1000 which was being driven by the K2. I would guess that the drive power was varying between 30 and 50 watts. Any thoughts on this? K2/100 5545 bought at Dayton this year, completed in September. Chris G3SJJ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Chris,
Take a look here... http://www.elecraft.com/Apps/Power_Control_Mod.html 73 Stewart G3RXQ On Wed, 27 Dec 2006 14:07:24 +0000, G3SJJ wrote: > I am sure I have seen a discussion about this one before. During an > > enjoyable 160m opening to the Right Coast just before Christmas I was > running a few Stateside stations and noticed a definite output power > variation coming from my Acom 1000 which was being driven by the K2. I > would guess that the drive power was varying between 30 and 50 watts. > Any thoughts on this? > > K2/100 5545 bought at Dayton this year, completed in September. > > Chris G3SJJ > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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No, that didn't help, Stewart. With the 100 PA disconnected and 5 watts
requested, I see around 0.5 w difference in actual power and that is stable. Having re-connected the 100 w pa to restore the K2/100 to the state I would normally use it, I have put a scope on the output. With requested power of 50w, in Tune the readout shows 29w immediately, dropping to 24, 21 and 17w, it then toggles between 17 and 22w. I can see this stepping on the waveform displayed on my scope. It also explains what I was seeing the other night. Since I was working pile-up style, the overs would be short, so each time I went to transmit the power variation in the K2 would also vary drive to the amp with the consequent output variation of between 100 and 200 w from the amp. Chris G3SJJ Stewart Baker wrote: > Chris, > Take a look here... http://www.elecraft.com/Apps/Power_Control_Mod.html > > 73 > Stewart G3RXQ > > On Wed, 27 Dec 2006 14:07:24 +0000, G3SJJ wrote: > >> I am sure I have seen a discussion about this one before. During an >> >> enjoyable 160m opening to the Right Coast just before Christmas I was >> running a few Stateside stations and noticed a definite output power >> variation coming from my Acom 1000 which was being driven by the K2. I >> would guess that the drive power was varying between 30 and 50 watts. >> Any thoughts on this? >> >> K2/100 5545 bought at Dayton this year, completed in September. >> >> Chris G3SJJ >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> > > > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I (and many others) have exactly the same power variation. I just recently
changed R99 to 1.1K and that reduced the variation in power to the point that I no longer notice the variations. A check of maximum power output shows that I still get normal performance on all bands. Don K7FJ > No, that didn't help, Stewart. With the 100 PA disconnected and 5 watts > requested, I see around 0.5 w difference in actual power and that is > stable. > > Having re-connected the 100 w pa to restore the K2/100 to the state I > would normally use it, I have put a scope on the output. With requested > power of 50w, in Tune the readout shows 29w immediately, dropping to 24, > 21 and 17w, it then toggles between 17 and 22w. I can see this stepping on > the waveform displayed on my scope. It also explains what I was seeing > the other night. Since I was working pile-up style, the overs would be > short, so each time I went to transmit the power variation in the K2 would > also vary drive to the amp with the consequent output variation of between > 100 and 200 w from the amp. > > Chris G3SJJ > > > > Stewart Baker wrote: >> Chris, >> Take a look here... http://www.elecraft.com/Apps/Power_Control_Mod.html >> >> 73 >> Stewart G3RXQ >> >> On Wed, 27 Dec 2006 14:07:24 +0000, G3SJJ wrote: >> >>> I am sure I have seen a discussion about this one before. During an >>> >>> enjoyable 160m opening to the Right Coast just before Christmas I was >>> running a few Stateside stations and noticed a definite output power >>> variation coming from my Acom 1000 which was being driven by the K2. I >>> would guess that the drive power was varying between 30 and 50 watts. >>> Any thoughts on this? >>> >>> K2/100 5545 bought at Dayton this year, completed in September. >>> >>> Chris G3SJJ >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> You must be a subscriber to post to the list. >>> Subscriber Info (Addr. Change, sub, unsub etc.): >>> http://mailman.qth.net/mailman/listinfo/elecraft >>> >>> Help: http://mailman.qth.net/subscribers.htm >>> Elecraft web page: http://www.elecraft.com >>> >> >> >> >> > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Chris G3SJJ
Chris,
You cannot make a sound judgement using TUNE. Evaluate the R98 value change with actual keying. If you change bands or change the power level, it will take a few dot times to settle into the new power setting, that part of your observation is normal. The rest of the situation is due to the loop response of the ALC control loop (that controls the power output) - it is quite with only the base K2, but adding the KPA100 can cause the loop to overshoot and oscillate - increasing R98 reduces the time constant of the loop and reduces the overshoot. Monitor the output on 10 meters during determining the maximum value for R98 - too much resistance will reduce the maximum power output on the higher bands, and yes you can compromise if you are willing to accept the lower power on 10 meters. 73, Don W3FPR > -----Original Message----- > > No, that didn't help, Stewart. With the 100 PA disconnected and 5 watts > requested, I see around 0.5 w difference in actual power and that > is stable. > > Having re-connected the 100 w pa to restore the K2/100 to the state I > would normally use it, I have put a scope on the output. With requested > power of 50w, in Tune the readout shows 29w immediately, dropping to 24, > 21 and 17w, it then toggles between 17 and 22w. I can see this stepping > on the waveform displayed on my scope. It also explains what I was > seeing the other night. Since I was working pile-up style, the overs > would be short, so each time I went to transmit the power variation in > the K2 would also vary drive to the amp with the consequent output > variation of between 100 and 200 w from the amp. > > Chris G3SJJ > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.15.28/605 - Release Date: 12/27/2006 12:21 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Yes I understand Don. I was using the TUNE effect to demonstrate what I see.
I performed the following test on 40m with my 2 element phased array connected and an SWR of 1:1. Keying with a series of dashes, K2 output power of 34 watts initially dropped to 26w then toggled between 26 and 34, this translated to an output power of 435w and 561w. With slightly more drive it oscillated between 42 and 50w producing about 670 and 830. The changeover time between the two levels is between 1 and 2 seconds. I didn't want to continuing QRMing the band so declined to check at full bore! (it is about 780w and 1kW for each state) Someone emailed me directly and said he had changed **R99** to 1.1K, so now I am not sure whether to change R98 or R99?? 73 Chris G3SJJ Don Wilhelm wrote: > Chris, > > You cannot make a sound judgement using TUNE. Evaluate the R98 value change > with actual keying. If you change bands or change the power level, it will > take a few dot times to settle into the new power setting, that part of your > observation is normal. > > The rest of the situation is due to the loop response of the ALC control > loop (that controls the power output) - it is quite with only the base K2, > but adding the KPA100 can cause the loop to overshoot and oscillate - > increasing R98 reduces the time constant of the loop and reduces the > overshoot. > > Monitor the output on 10 meters during determining the maximum value for > R98 - too much resistance will reduce the maximum power output on the higher > bands, and yes you can compromise if you are willing to accept the lower > power on 10 meters. > > 73, > Don W3FPR > > >> -----Original Message----- >> >> No, that didn't help, Stewart. With the 100 PA disconnected and 5 watts >> requested, I see around 0.5 w difference in actual power and that >> is stable. >> >> Having re-connected the 100 w pa to restore the K2/100 to the state I >> would normally use it, I have put a scope on the output. With requested >> power of 50w, in Tune the readout shows 29w immediately, dropping to 24, >> 21 and 17w, it then toggles between 17 and 22w. I can see this stepping >> on the waveform displayed on my scope. It also explains what I was >> seeing the other night. Since I was working pile-up style, the overs >> would be short, so each time I went to transmit the power variation in >> the K2 would also vary drive to the amp with the consequent output >> variation of between 100 and 200 w from the amp. >> >> Chris G3SJJ >> >> > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.5.432 / Virus Database: 268.15.28/605 - Release Date: 12/27/2006 > 12:21 PM > > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Sorry, that was my email .... I should have said R98.
Don K7FJ > Someone emailed me directly and said he had changed **R99** to 1.1K, so > now I am not sure whether to change R98 or R99?? > > 73 Chris G3SJJ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Yes thanks Don. R99 is also mentioned in
http://www.elecraft.com/Apps/Power_Control_Mod.html so I was getting a bit confused! 73 Chris G3SJJ Don wrote: > Sorry, that was my email .... I should have said R98. > > Don K7FJ > >> Someone emailed me directly and said he had changed **R99** to 1.1K, >> so now I am not sure whether to change R98 or R99?? >> >> 73 Chris G3SJJ > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Chris,
The mention of R99 in that article was only to check it and be certain it is 270 ohms. All the rest of the text refers to changing R98. 73, Don W3FPR > -----Original Message----- > > Yes thanks Don. R99 is also mentioned in > http://www.elecraft.com/Apps/Power_Control_Mod.html so I was getting a > bit confused! > > 73 Chris G3SJJ > > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.15.28/605 - Release Date: 12/27/2006 12:21 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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