Re: [Elecraft] KPA500 Power In Digital Modes
On Wed,11/19/2014 11:45 AM, Joe Subich, W4TV wrote: Joe made this statement assuming that the KPA500 produced FAR more distortion than it actually does. A few days later, I showed measurements with a K3 driving a KPA500 to 500W with PSK31 showing that the distortion was EXTREMELY low. Jim, is misconstruing what I wrote. I specifically said *average* power from the KPA-500 should be kept 6-10 dB below the maximum. Jim made his measurements at PEP which *includes* the crest factor (PEP = average power X Crest factor or alternately Average Power = PEP/Crest Factor). If his measurements were made at average power, the results would have been considerably different. Joe, you must misunderstand my measurements. They are ACCUMULATED peaks for a fairly long measuring period, so they show transient clicks and other forms of distortion far better than an averaged measurement. Indeed, I showed measurements of the KPA500 running at 500W out that have very low distortion (as indicated by occupied bandwidth). Yes, bandwidth (and distortion) increases at bit if the KPA500 is driven harder. As to peak and average power -- the measurements are of Peak Envelope Power, which for CW, RTTY, PSK31, and the WSJT modes is keydown power, and for all but CW, is the same as the Average Power. The average power is less on CW because of the spaces between elements. Crest Factor is relevant only on SSB. For normal speech, crest factors range between 10 and 20 dB. We often use compression to reduce that Crest Factor, and the K3 sounds very good when it is set for about 10 dB of compression on peaks. I haven't measured the resulting Crest factors, but long experience in pro audio suggests values of 6-10 dB would be the result. The KPA500 is quite well protected against conditions of overload. It will add resistive attenuation if overdriven by as little as a dB and/or into a poorly matched load, and will Fault if overdriven by a lot. Thus, it is probably not possible to drive a KPA500 deep into saturation. This is true regardless of the type of modulation in use (CW is modulation by a square wave). The highest power measurements I made of the KPA500 were at the level which more drive would have caused that resistive attenuation to be added. Indeed, the only way to reduce the Crest Factor with a KPA500 is to apply more compression to the driving signal. Note also that I showed measurements of the K3 driving a very good legal limit tube amp to its rated power, and the waveforms were nearly identical. That tube amp, a Titan 425, has no protection circuitry, only a red LED indicating excessive grid current. So -- the ONLY way in which my measurements show better numbers than an averaged measurement is that they use peak power as a reference, and applies ONLY to the SSB measurements. 73, Jim K9YC __ 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] KPA500 Power In Digital Modes
On Nov 10, 2014, at 7:30 PM, Joe Subich, W4TV wrote: Depending on the crest factor (peak to average ratio) of the mode in use, the average power from the KPA-5000 should be kept 6 to 10 dB below the rated maximum (e.g., 60 to 150 watts) just as a 100W transceiver should be kept between 10 and 25 watts average. Since the K3 turns off the final stage when below 13 watts, does that mean running 10 watts is a bad choice since that's running the lower power stage at near maximum? From a cooling perspective alone, I have often wondered if it's better for a K3 to be run at 15w rather than 10. Ken WA8JXM __ 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] KPA500 Power In Digital Modes
Since the K3 turns off the final stage when below 13 watts, does that mean running 10 watts is a bad choice since that's running the lower power stage at near maximum? As it relates to that part of the distortion caused by compression or clipping in the amplifier chain (IF- Low power amplifier - PA), running the K3 at 10 watts is probably worse than running it at 20 watts. I don't have specific data on the particular devices used in the K3 but in general IMD is minimum around 80% of maximum rated output. 73, ... Joe, W4TV On 2014-11-19 6:50 AM, Ken wrote: On Nov 10, 2014, at 7:30 PM, Joe Subich, W4TV wrote: Depending on the crest factor (peak to average ratio) of the mode in use, the average power from the KPA-5000 should be kept 6 to 10 dB below the rated maximum (e.g., 60 to 150 watts) just as a 100W transceiver should be kept between 10 and 25 watts average. Since the K3 turns off the final stage when below 13 watts, does that mean running 10 watts is a bad choice since that's running the lower power stage at near maximum? From a cooling perspective alone, I have often wondered if it's better for a K3 to be run at 15w rather than 10. Ken WA8JXM __ 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] KPA500 Power In Digital Modes
On Wed,11/19/2014 3:50 AM, Ken wrote: On Nov 10, 2014, at 7:30 PM, Joe Subich, W4TV wrote: Depending on the crest factor (peak to average ratio) of the mode in use, the average power from the KPA-5000 should be kept 6 to 10 dB below the rated maximum (e.g., 60 to 150 watts) just as a 100W transceiver should be kept between 10 and 25 watts average. Joe made this statement assuming that the KPA500 produced FAR more distortion than it actually does. A few days later, I showed measurements with a K3 driving a KPA500 to 500W with PSK31 showing that the distortion was EXTREMELY low. I had already published comparable measurements for CW and SSB, with the same result. P3SpectrumMeasurementsSlides.pdf 73, Jim K9YC __ 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] KPA500 Power In Digital Modes
Joe made this statement assuming that the KPA500 produced FAR more distortion than it actually does. A few days later, I showed measurements with a K3 driving a KPA500 to 500W with PSK31 showing that the distortion was EXTREMELY low. Jim, is misconstruing what I wrote. I specifically said *average* power from the KPA-500 should be kept 6-10 dB below the maximum. Jim made his measurements at PEP which *includes* the crest factor (PEP = average power X Crest factor or alternately Average Power = PEP/Crest Factor). If his measurements were made at average power, the results would have been considerably different. With most PSK, MFSK, PACTOR, etc. modes, it is important that the average power output be kept low enough that none of the amplifier stages is driven into saturation on the peaks which can be anywhere from 3 dB to 13 dB greater than average depending on the digital modulation. Note: FSK, JT65 and JT9 modes are saturated - their crest factor is 1 (0 dB). Like CW, for those modes, PEP = average power. 73, ... Joe, W4TV On 2014-11-19 11:49 AM, Jim Brown wrote: On Wed,11/19/2014 3:50 AM, Ken wrote: On Nov 10, 2014, at 7:30 PM, Joe Subich, W4TV wrote: Depending on the crest factor (peak to average ratio) of the mode in use, the average power from the KPA-5000 should be kept 6 to 10 dB below the rated maximum (e.g., 60 to 150 watts) just as a 100W transceiver should be kept between 10 and 25 watts average. Joe made this statement assuming that the KPA500 produced FAR more distortion than it actually does. A few days later, I showed measurements with a K3 driving a KPA500 to 500W with PSK31 showing that the distortion was EXTREMELY low. I had already published comparable measurements for CW and SSB, with the same result. P3SpectrumMeasurementsSlides.pdf 73, Jim K9YC __ 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 li...@subich.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] KPA500 Power In Digital Modes
On Mon,11/10/2014 4:59 PM, mcduf...@ag0n.net wrote: Full linearity is needed for these modes to keep IMD under control. Huh? Full linearity would be zero distortion. ALL amplifiers have some amplitude distortion. See ARRL test results for a sample of current products. 2-tone IMD in the range of -30dB is pretty common. In the link I just posted, look at the occupied bandwidth of the K3 driving a KPA500 to full power, and to a few dB less power, then compare to the K3 driving a triode tube amp to legal limit. The IMD sidedbands are clearly visible, even with a CW signal -- remember that a CW signal is a carrier amplitude modulated by a square wave. The square wave has harmonic content (as a function of its rise time and shaping), so it produces IM. 73, Jim K9YC __ 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] KPA500 Power In Digital Modes
On Mon,11/10/2014 11:20 PM, Jim Brown wrote: P3SprectrumMeasurementsSlides.pdf That should be k9yc.com/P3SprectrumMeasurementsSlides.pdf __ 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] KPA500 Power In Digital Modes
On 11/10/2014 5:56 PM, mcduf...@ag0n.net wrote: On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. I cannot get my KPA500 to run more than about 200W on 6M without getting a PA DISS fault. Temp is not even up to 60C yet. Between that and the KAT500 coming 'untuned' and faulting in the middle of a QSO on 10M, I'm about ready to throw them both in the trash and go back to my tube amp. Mike KI0HA __ 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] KPA500 Power In Digital Modes
Funny, just yesterday I was looking at CW signals on my P3, noting the skinny ones and the ones with fat bottoms. When you listen off the side of the fat ones, of course, you can hear the clicks. I happened to tune to one of the skinny ones just in time to hear the operator say he was a using a K3. On 11 Nov 2014 10:08, Jim Brown wrote: On Mon,11/10/2014 11:20 PM, Jim Brown wrote: P3SprectrumMeasurementsSlides.pdf That should be k9yc.com/P3SprectrumMeasurementsSlides.pdf -- 73, Vic, 4X6GP/K2VCO Rehovot, Israel http://www.qsl.net/k2vco/ __ 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] KPA500 Power In Digital Modes
This happened with my KPA500 until I realized that my Microham double-six antenna switch is only rated to max 30MHz.The SWR was fine, but KPA 500 kept faulting on 6 with High PA DISS fault code. Once i connected my 3el SteppIR directly into the amp, it works full steam on 6 meters. 73, Nick ve3ey I cannot get my KPA500 to run more than about 200W on 6M without getting a PA DISS fault. Temp is not even up to 60C yet. On Nov 11, 2014, at 5:30 AM, Michael Eberle mtebe...@mchsi.com wrote: I cannot get my KPA500 to run more than about 200W on 6M without getting a PA DISS fault. Temp is not even up to 60C yet. __ 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] KPA500 Power In Digital Modes
Don't do it! If you can't get an answer here, contact Elecraft support. Your KPA500 will work great on 6m once you get this issue resolved. Mine runs at 600w on 6m meteor scatter using FSK441 30 seconds on, 30 seconds off, for hours on end, hitting 65C but soldiering on without complaint. That would leave my former dual 3-500Z amp squeaking from the freaking. 73 Eric WD6DBM Michael Eberle mtebe...@mchsi.com wrote: On 11/10/2014 5:56 PM, mcduf...@ag0n.net wrote: On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. I cannot get my KPA500 to run more than about 200W on 6M without getting a PA DISS fault. Temp is not even up to 60C yet. Between that and the KAT500 coming 'untuned' and faulting in the middle of a QSO on 10M, I'm about ready to throw them both in the trash and go back to my tube amp. Mike KI0HA __ 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 norrislawfi...@gmail.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] KPA500 Power In Digital Modes
Yes, I suppose something may just need a slight adjustment. It just frustrates me when things don't work like I expect them to. I was always afraid to run JT65 at more than 80-100 watts until I saw this post. Started trying higher power while keeping a close eye on the temp. No faults on any band but 6M if it gets much over 200 watts (8 watts drive). It seems to be running 450 watts easily on 160M. On 11/11/2014 5:44 AM, Eric Norris wrote: Don't do it! If you can't get an answer here, contact Elecraft support. Your KPA500 will work great on 6m once you get this issue resolved. Mine runs at 600w on 6m meteor scatter using FSK441 30 seconds on, 30 seconds off, for hours on end, hitting 65C but soldiering on without complaint. That would leave my former dual 3-500Z amp squeaking from the freaking. 73 Eric WD6DBM Michael Eberle mtebe...@mchsi.com wrote: On 11/10/2014 5:56 PM, mcduf...@ag0n.net wrote: On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. __ 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] KPA500 Power In Digital Modes
On Tue, 11 Nov 2014 00:06:53 -0800, Jim Brown wrote: Huh? Full linearity would be zero distortion. I knew I shouldn't have used that word. :o) Gary __ 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] KPA500 Power In Digital Modes
On Tue, 11 Nov 2014 04:30:17 -0600, Michael Eberle wrote: I cannot get my KPA500 to run more than about 200W on 6M without getting a PA DISS fault. Temp is not even up to 60C yet. Between that and the KAT500 coming 'untuned' and faulting in the middle of a QSO on 10M, I'm about ready to throw them both in the trash and go back to my tube amp. Sounds like you have some problem between the amplifier and the antenna. Yes, that's a broad area, but includes it all. I had similar problem for awhile and found various small things that lower power didn't show up. Clean up the system, get rid of bad jumpers, clean the connections, and try it again. But first, shove a dummy load on it and see that it runs full power with no problem. If it doesn't, make sure the load is plugged directly into the amp with a good jumper. Eliminate every connection one by one until you find it...and then keep looking all the way to the antenna to clean up the whole system. Gary __ 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] KPA500 Power In Digital Modes
Jim, Recent measurements I've done of a K3 driving a KPA500 both with pink noise on USB and keyed CW show that not to be the case. Your measurements are not of the conditions I describe. You are using *filtered and band limited pink noise* (slide #3 - EQ settings) not the specific digital signals I mention *and* your measurements are at PEP not average power (slide #2 - LP-100A set to peak). In addition, unfiltered pink noise has a crest factor (peak to average ratio) of 3 dB which you are further reducing by compression in the K3 - not the 6 to 10 dB crest factors of the specified digital modes which *can not* be compressed without significant distortion and IMD. Your measurements, while interesting, do not accurately simulate the specified digital modes are not applicable in this case. 73, ... Joe, W4TV On 2014-11-11 2:20 AM, Jim Brown wrote: On Mon,11/10/2014 4:30 PM, Joe Subich, W4TV wrote: *DO NOT* try running PSK, MFSK, etc. modes at 600W average power from a KPA-500 as you will be generating serious IMD and garbage. Recent measurements I've done of a K3 driving a KPA500 both with pink noise on USB and keyed CW show that not to be the case. Yes, bandwidth increases a few dB from 400W to 600W, but I would NOT call it serious. This is preliminary work and a preliminary report. At its current stage, it's a proof of concept.As I have time (and the radios to test), I plan to look at lot of others. I've just lined up a couple in the FT1000MP family. P3SprectrumMeasurementsSlides.pdf 73, Jim K9YC __ 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 li...@subich.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] KPA500 Power In Digital Modes
On Tue,11/11/2014 3:26 AM, Nick-VE3EY wrote: This happened with my KPA500 until I realized that my Microham double-six antenna switch is only rated to max 30MHz. Nothing specific about this antenna switch -- getting any matrix switch like that to have low SWR at 6M is quite tricky to do. I had a similar problem with a different 2x6 switch on 6M -- rather high SWR. My solution was to not run my SteppIR through that switch. Instead, I feed it directly into one output of my KAT500. The matrix switch feeds a different input of the KAT500. I also found that other stuff I had in series with the path between the KPA500 and the tuner was increasing to the SWR -- a not very good power/SWR meter and a tapoff for a monitor scope. I also found a few junk connectors connecting that stuff. Bottom line -- when I cleaned up the signal path, SWR went from slightly more than 2:1 down to 1.1:1. 73, Jim K9YC __ 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] KPA500 Power In Digital Modes
As others have said, check your jumpers, and especially any barrel or elbow connectors you bought at a hamfest. They are junk. I learned the hard way that paying through the nose for good connectors, like Amphenol, is cheaper than buying a new 3CX800 tube, and saves hours of frustration. Save them for QRP--that's all they are good for. 73 Eric WD6DBM Michael Eberle mtebe...@mchsi.com wrote: Yes, I suppose something may just need a slight adjustment. It just frustrates me when things don't work like I expect them to. I was always afraid to run JT65 at more than 80-100 watts until I saw this post. Started trying higher power while keeping a close eye on the temp. No faults on any band but 6M if it gets much over 200 watts (8 watts drive). It seems to be running 450 watts easily on 160M. On 11/11/2014 5:44 AM, Eric Norris wrote: Don't do it! If you can't get an answer here, contact Elecraft support. Your KPA500 will work great on 6m once you get this issue resolved. Mine runs at 600w on 6m meteor scatter using FSK441 30 seconds on, 30 seconds off, for hours on end, hitting 65C but soldiering on without complaint. That would leave my former dual 3-500Z amp squeaking from the freaking. 73 Eric WD6DBM Michael Eberle mtebe...@mchsi.com wrote: On 11/10/2014 5:56 PM, mcduf...@ag0n.net wrote: On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. __ 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] KPA500 Power In Digital Modes
I would submit that if they're no good for QRO, they're no good for QRP as well (where every erg counts). Buy then use quality materials, it matters. Rick, WA6NHC iPad = small keypad = typos = sorry ;-) On Nov 11, 2014, at 12:02 PM, Eric Norris norrislawfi...@gmail.com wrote: Save them for QRP--that's all they are good 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 Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Power In Digital Modes
On Tue,11/11/2014 7:17 AM, Joe Subich, W4TV wrote: Your measurements are not of the conditions I describe. You are using *filtered and band limited pink noise* (slide #3 - EQ settings) not the specific digital signals I mention *and* your measurements are at PEP not average power (slide #2 - LP-100A set to peak). Right -- my test conditions for SSB are MORE demanding than either PSK31 or JT65A, and were intended to approximate the response of the K3 (and amp) to a speech signal. I also made one measurement of the K3 at high power without compression. Occupied bandwidth was nearly identical to the 10dB compression, so I did the rest with compression. Did you miss the CW measurements, where the modulation was a shaped square wave? When I have time (I'm currently hot and heavy with antenna work), I will, however, repeat these measurements with a PSK31 test signal, and with JT65A. I don't expect the results to be a lot different. 73, Jim K9YC __ 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] KPA500 Power In Digital Modes
Then you have a problem. I regularly run my KPA500/KAT500 at full power on every band, including 10M and 6M in all modes, CW, SSB, RTTY, FSK441 etc. As for the KAT500 faulting, I always run the KAT500 in manual mode. It knows where to tune for my modes of operation and the frequencies I operate (like the CW DX windows, RTTY frequencies etc). If it doesn't then I hit the TUNE button. 73s Jim, W4ATK On 11/11/2014 4:30 AM, Michael Eberle wrote: On 11/10/2014 5:56 PM, mcduf...@ag0n.net wrote: On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. I cannot get my KPA500 to run more than about 200W on 6M without getting a PA DISS fault. Temp is not even up to 60C yet. Between that and the KAT500 coming 'untuned' and faulting in the middle of a QSO on 10M, I'm about ready to throw them both in the trash and go back to my tube amp. Mike KI0HA __ 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 jim.w4...@gmail.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] KPA500 Power In Digital Modes
Jim, Right -- my test conditions for SSB are MORE demanding than either PSK31 or JT65A, and were intended to approximate the response of the K3 (and amp) to a speech signal. That SSB is *more* demanding than PSK31 is incorrect. SSB audio can be compressed/clipped significantly without IMD if the compression is done correctly. PSK31 on the other hand *can not* withstand *any* compression without significant close-in IMD. See the work by W7AY for that information. JT65A (and other JT modes) on the other hand is a saturated single tone mode akin to FSK that has *no issue* with compression and is, in fact, not compressible. When I have time (I'm currently hot and heavy with antenna work), I will, however, repeat these measurements with a PSK31 test signal, and with JT65A. I don't expect the results to be a lot different. If you do the measurements correctly, they will be a LOT different. JT65A will show little or no change in IMD from 25 to 100 W average (and PEP) output on the K3 (or 100W to 600W average and PEP output on the KPA-500. PSK31, however, will go to pot in a hand basket if the average power output on the K3 goes above 30 watts or so or if the average power output of the KPA500 goes above 150 watts or so. If you are measuring *TRUE* peak power, those are equivalent to 100-110 W PEP from the K3 or 600W PEP on the KPA500 given the 6 dB crest ratio in the PSK31 waveform. JT65 and JT9 (all sub-modes) have a 0 dB crest factor, PSK31 has a 6 dB crest factor - other modern data modes have various crest factors - you need to understand the crest factor of the input waveform. Did you miss the CW measurements, where the modulation was a shaped square wave? No, I did not miss the CW measurements - they have no bearing on the issues here. 73, ... Joe, W4TV On 2014-11-11 4:07 PM, Jim Brown wrote: On Tue,11/11/2014 7:17 AM, Joe Subich, W4TV wrote: Your measurements are not of the conditions I describe. You are using *filtered and band limited pink noise* (slide #3 - EQ settings) not the specific digital signals I mention *and* your measurements are at PEP not average power (slide #2 - LP-100A set to peak). Right -- my test conditions for SSB are MORE demanding than either PSK31 or JT65A, and were intended to approximate the response of the K3 (and amp) to a speech signal. I also made one measurement of the K3 at high power without compression. Occupied bandwidth was nearly identical to the 10dB compression, so I did the rest with compression. Did you miss the CW measurements, where the modulation was a shaped square wave? When I have time (I'm currently hot and heavy with antenna work), I will, however, repeat these measurements with a PSK31 test signal, and with JT65A. I don't expect the results to be a lot different. 73, Jim K9YC __ 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 li...@subich.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] KPA500 Power In Digital Modes
I would submit that if they're no good for QRO, they're no good for QRP as well (where every erg counts). Buy then use quality materials, it matters. This discussion reminds me of the problem Radio Shack introduced when they sold some elbows that actually used a small diameter coil spring for a center conductor going around the 90 degree bend. Think about that for a minute and realize what happened when they were used on higher frequencies. Gary __ 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] KPA500 Power In Digital Modes
On Tue,11/11/2014 2:33 PM, Joe Subich, W4TV wrote: PSK31 on the other hand *can not* withstand *any* compression without significant close-in IMD. I don't know where you got the idea that I was suggesting compression for PSK31. My testing with pink noise is intended to simulate speech, and I tested with and without compression. It's raining, which stops antenna work, so I set up PSK31 measurements this afternoon. Here's a link to the data. Note that I used PSK-D mode -- internally generated by the K3. http://k9yc.com/P3SpectrumMeasurementsSlides.pdf Note that, except at full power, PSK31 is significantly narrower than CW. 73, Jim K9YC __ 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
[Elecraft] KPA500 Power In Digital Modes
On Sun,11/9/2014 2:18 PM, Phil Wheeler wrote: How much power out were you running on RTTY with your KPA500? I'm interested because I have the amp, but have not yet used it on digital modes (use the K3 barefoot at 25 W or so). During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. 73, Jim K9YC __ 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] KPA500 Power In Digital Modes
On Mon, Nov 10, 2014 at 9:34 AM, Jim Brown j...@audiosystemsgroup.com wrote: On Sun,11/9/2014 2:18 PM, Phil Wheeler wrote: How much power out were you running on RTTY with your KPA500? I'm interested because I have the amp, but have not yet used it on digital modes (use the K3 barefoot at 25 W or so). During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. Just to echo what Jim said, we used the KPA500 at W7RN on RTTY for W1AW/7 NV WARC bands at full output, ran as cool as a clam. 73 jeff wk6i -- Jeff Stai ~ wk6i.j...@gmail.com Twisted Oak Winery ~ http://www.twistedoak.com/ Facebook ~ http://www.facebook.com/twistedoak __ 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] KPA500 Power In Digital Modes
On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. I'm not a contester, but have done similar with mine with no issue. The fan will scream at you as it gets above 70C, but the temp levels out. I'm not one to push much beyond that, as that's all the warmer it gets in JT exchanges running power. No lectures on low power for JT, I run power depending on propagation, or lack thereof, mostly on a dead six meter band. Gary __ 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] KPA500 Power In Digital Modes
No lectures on low power for JT, I run power depending on propagation, or lack thereof, mostly on a dead six meter band. Note that JT65 and JT9 are designed to be suitable for saturated amplifiers as there is only a single tone at a time and one tone ramps down before the next tone ramps up. *DO NOT* try running PSK, MFSK, etc. modes at 600W average power from a KPA-500 as you will be generating serious IMD and garbage. Depending on the crest factor (peak to average ratio) of the mode in use, the average power from the KPA-5000 should be kept 6 to 10 dB below the rated maximum (e.g., 60 to 150 watts) just as a 100W transceiver should be kept between 10 and 25 watts average. 73, ... Joe, W4TV On 2014-11-10 6:56 PM, mcduf...@ag0n.net wrote: On Mon, 10 Nov 2014 09:34:09 -0800, Jim Brown wrote: During KPA500 beta, I was loaned one for a major RTTY contest weekend and told to run it with all the lights lit. I did, and it worked fine. In the 3-4 years I've owned one, I regularly run it at full power in digital modes on all bands, 160-6M. When it gets warm, the fan speeds up, but it continues to put out full power. This includes digital modes like FSK441 and JT65A on 6M, and lots of RTTY on the HF bands. I'm not a contester, but have done similar with mine with no issue. The fan will scream at you as it gets above 70C, but the temp levels out. I'm not one to push much beyond that, as that's all the warmer it gets in JT exchanges running power. No lectures on low power for JT, I run power depending on propagation, or lack thereof, mostly on a dead six meter band. Gary __ 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 li...@subich.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] KPA500 Power In Digital Modes
On Mon, 10 Nov 2014 19:30:01 -0500, Joe Subich, W4TV wrote: Note that JT65 and JT9 are designed to be suitable for saturated amplifiers as there is only a single tone at a time and one tone ramps down before the next tone ramps up. *DO NOT* try running PSK, MFSK, etc. modes at 600W average power from a KPA-500 as you will be generating serious IMD and garbage. Correct. Full linearity is needed for these modes to keep IMD under control. Gary __ 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] KPA500 Power In Digital Modes
On Mon, 10 Nov 2014 16:56:57 -0700, mcduf...@ag0n.net wrote: I'm not one to push much beyond that, as that's all the warmer it gets in JT exchanges running power. No lectures on low power for JT, I run power depending on propagation, or lack thereof, mostly on a dead six meter band. I should add, I'll be glad to make test temp readings for anyone wanting them. I have a digital thermometer sensor in the fan grate to show outlet temperatures and I monitor the internal temp via the front panel readout any time I'm using it, even when on SSB, where the fan almost never runs. In addition, I have an IR thermometer and can spot check anywhere outside the temp (except bottom) for you if needed. Just contact me directly. Gary __ 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] KPA500 Power In Digital Modes
On Mon,11/10/2014 4:30 PM, Joe Subich, W4TV wrote: *DO NOT* try running PSK, MFSK, etc. modes at 600W average power from a KPA-500 as you will be generating serious IMD and garbage. Recent measurements I've done of a K3 driving a KPA500 both with pink noise on USB and keyed CW show that not to be the case. Yes, bandwidth increases a few dB from 400W to 600W, but I would NOT call it serious. This is preliminary work and a preliminary report. At its current stage, it's a proof of concept.As I have time (and the radios to test), I plan to look at lot of others. I've just lined up a couple in the FT1000MP family. P3SprectrumMeasurementsSlides.pdf 73, Jim K9YC __ 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
