Re: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
> If the onboard meter _thought_ the K3 was making the requested > power, that would be one thing. But in this case the onboard > meter thinks it's putting out 2x the power, which it is. It depends on what part of the system thinks what. In this case the MCU is reading a given value but interpreting it as something else thanks to TXG VCE. TXG VCE does not effect the peak power in SSB or AFSK A with single tone modulation. It does effect peak power in DATA A. If you are seeing about 2x the power called for, decrease TXG VCE by 3 dB and see if the situation does not resolve itself (at the expense of power output in USB/LSB). Although the wattmeter is peak reading according to Wayne, TXG VCE still provides an inappropriate "adjustment." 73, ... Joe, W4TV > -Original Message- > From: Steve Ward [mailto:stev...@spiritone.com] > Sent: Monday, January 05, 2009 3:38 AM > To: li...@subich.com > Subject: Re: [Elecraft] K3: Still unable to set power > correctly in, DATA A(sigh) > > > Joe, > > If the onboard meter _thought_ the K3 was making the requested power, > that would be one thing. But in this case the onboard meter > thinks it's > putting out 2x the power, which it is. So, I dial in 40w and > I get 80w > both by the internal meter and by my admittedly less than lab-quality > MFJ dummy load+meter. > > It did not do this before the most recent firmware. > Something got broken... > > 73, > > Steve AD7OG > > Joe Subich, W4TV wrote: > > > >> The point is it was providing the correct power output levels > >> before the last couple of firmware revisions. Something > >> changed that made it go from putting out approximately the > >> right power level, to putting out WAY TOO MUCH (i.e. causing > >> splatter) power. > >> > > > > Not true ... in spite of careful calibration at both 5 and 50 > > watt levels neither of my K3s has ever produced exactly the > > power requested on any band other than 20 meters, on any mode > > other than CW and at any power other than 5 or 50 watts. The > > variations can be as much as 3 dB on SSB depending on the peak > > to average ratio of the driving audio and amount of compression > > used. > > > > Setting a power control calibrated for CW and expecting that > > level to be accurate for PSK31 or any other arbitrary digital > > modulation is complete folly and utter hubris. Among other > > issues the wattmeter does not know if you are setting peak > > or average power and it does not know what the average power > > should be for the arbitrary data and arbitrary modulation. > > > > For the K3 to accurately control the power level in all modes > > the its directional coupler would probably need to be improved > > by at least an order or magnitude. The response flatness would > > need to be improved by at least an octave and the detectors would > > need to be substantially more linear ... and that's just for CW. > > To handle arbitrary audio inputs takes some knowledge of the > > peak to average ratio as well as the peak duration (duty cycle) > > in order to select the proper detector time constants. Every > > voice every digital mode and every arbitrary data stream will > > have different peak to average ratios and duty cycles. Do you > > expect the DSP to calculate those values on the fly? Perhaps > > the power metering should be derived from a DSP based spectrum > > analyzer? > > > > Accept the fact that the power level control is relative. If > > Wayne and Lyle can improve on it that's great. However, trying > > to hold .1 dB or even 1 dB accuracy from 1 mW to 120 W, 1.8 MHz > > to 54 MHz with arbitrary modulation sources in a reasonably > > priced amateur transceiver is a fool's errand. > > > > 73, > > > >... Joe, W4TV > > > > > > > > > > > >> -Original Message- > >> From: elecraft-boun...@mailman.qth.net > >> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Steve Ward > >> Sent: Saturday, January 03, 2009 2:54 PM > >> To: elecraft@mailman.qth.net > >> Subject: [Elecraft] K3: Still unable to set power correctly > >> in, DATA A(sigh) > >> > >> > >> "Joe Subich, W4TV" Wrote: > >> > >> > >>> So? Reduce the power you request to get the required > output. What > >>> other radio has a "calibrated" power output control? > >>> > >>>
Re: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
G4LNA wrote: > > > I'm not asserting anything, what I said applies to any rig you care to > mention, I don't believe meters. No matter what magic wizardry circuits or > software is contained in the rig to deceive to meter into reading power, > you can't beat seeing the peak power reading on an oscilloscope. > > I did have a look at the peak output of my rig and notice the meter > doesn't correspond to the peak power reading on the K3, it doesn't even > come close, that doesn't worry me in the slightest because I don't use the > meter for power setting on anything apart from CW. > > What I will assert is that every radio amateur should at least have an > oscilloscope as basic test equipment and learn how to use it, perhaps > there wouldn't be so many rubbish signals on the air, there again, if pigs > fly... > > I'm not pointing a finger at you Julian, I think you may agree there are a > lot of amateurs who do rely on meters without understanding what is really > happening in the real world, because now a days they are not taught basic > understanding of what is happening to a modulated RF signal. > > An oscilloscope is one of the main bits of test gear an RF engineer can > own, after all, that's what we are, RF engineers and oscilloscopes are > cheap to buy. > > It would be very nice if we were all able to do this, but your statement takes no account of individuals' circumstances. You are from the UK, so you know what most of our houses are like. Take a look at the picture on the front page of my website. My "shack" has to share desk space with my home office, and meet the aesthetic criteria of my XYL. I don't have the luxury of a dedicated radio room I can cram with test equipment, and there are a lot of us like that. If radio manufacturers required customers to have a lab full of test gear then the market for their products would be so limited they'd be out of business. Elecraft does not recommend never mind require an oscilloscope not even when constructing a K2 from parts. I successfully built one using nothing more in the way of test equipment than a £5 DMM and a home made power meter. If you are building gear from scratch then a scope probably is very useful, but if you are paying $3,000 for a factory aligned transceiver from any manufacturer then you ought to be confident that it puts out a clean signal as long as you operate it in accordance with the instructions. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in%2C-DATA-A%28sigh%29-tp2106764p2110764.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
Peter Connors, F5VNB wrote: > > > To assert that every K3 owner needs an oscilliscope or laboratory grade > peak reading meter in order to ensure that they never exceed a given peak > power because the K3 internal circuits are incapable of doing so is a very > serious criticism indeed. > I'm not asserting anything, what I said applies to any rig you care to mention, I don't believe meters. No matter what magic wizardry circuits or software is contained in the rig to deceive to meter into reading power, you can't beat seeing the peak power reading on an oscilloscope. I did have a look at the peak output of my rig and notice the meter doesn't correspond to the peak power reading on the K3, it doesn't even come close, that doesn't worry me in the slightest because I don't use the meter for power setting on anything apart from CW. What I will assert is that every radio amateur should at least have an oscilloscope as basic test equipment and learn how to use it, perhaps there wouldn't be so many rubbish signals on the air, there again, if pigs fly... I'm not pointing a finger at you Julian, I think you may agree there are a lot of amateurs who do rely on meters without understanding what is really happening in the real world, because now a days they are not taught basic understanding of what is happening to a modulated RF signal. An oscilloscope is one of the main bits of test gear an RF engineer can own, after all, that's what we are, RF engineers and oscilloscopes are cheap to buy. -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in%2C-DATA-A%28sigh%29-tp2106764p2110422.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
While that might be a solution, it causes other... Why should the firmware not be able to both? Assuming that there are no hardware limitations, I would think it should fairly easily be possible to do peak readings and average readings as needed by the firmware, in the firmware, for the firmware. BTW: I've always felt that the power control in SSB could be better and way back when (i.e. I can't remember which firmware version) it was not very good at all, to put it mildly. At least in SSB the power control has been improved markedly over the last year, even if it is not 100% perfect (yet). I've only used DATA-A once, for a quick experimental PSK QSO several months ago, and at the time I didn't notice any problems. I'm sure that Wayne & Lyle will find a good solution... vy 73 de toby -- DD5FZ K2 #885 K2/100 #3248 k3/100 #67 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
> Whatever the peak/average ratio of the modulation, the output > power from the PA is peak limited - so wouldn't the answer be > a K3 power meter and power control that shows/sets peak rather > than average power? While that might be a solution, it causes other problems. The wattmeter is used to measure SWR. If the wattmeter reads peak power in forward it must also be beak reading in reverse in order to calculate/display SWR instead of reflected power. Peak reading reflected power makes it difficult for the MCU to adjust the tuner (if installed) and makes it nearly impossible to adjust while in operation rather than "tune" mode due to the time constant of the peak reading circuits. I don't know of any transceiver that combines a peak reading wattmeter with a tuner. 73, ... Joe, W4TV > -Original Message- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Peter > Connors, F5VNB > Sent: Sunday, January 04, 2009 3:46 AM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3: Still unable to set power > correctly in,DATA A(sigh) > > > Joe > > Thank you for pointing out the difficulties in setting average power > across a range of modulation types. > Whatever the peak/average ratio of the modulation, the output > power from > the PA is peak limited - so wouldn't the answer be a K3 power > meter and > power control that shows/sets peak rather than average power? > The power > control would then be set just once and the average power would be an > unavoidable consequence of the choice of modulation. > > 73, Pete F5VNB > > Joe Subich, W4TV wrote: > > > > > > Setting a power control calibrated for CW and expecting that > > level to be accurate for PSK31 or any other arbitrary digital > > modulation is complete folly and utter hubris. Among other > > issues the wattmeter does not know if you are setting peak > > or average power and it does not know what the average power > > should be for the arbitrary data and arbitrary modulation. > > > > For the K3 to accurately control the power level in all modes > > the its directional coupler would probably need to be improved > > by at least an order or magnitude. The response flatness would > > need to be improved by at least an octave and the detectors would > > need to be substantially more linear ... and that's just for CW. > > To handle arbitrary audio inputs takes some knowledge of the > > peak to average ratio as well as the peak duration (duty cycle) > > in order to select the proper detector time constants. Every > > voice every digital mode and every arbitrary data stream will > > have different peak to average ratios and duty cycles. Do you > > expect the DSP to calculate those values on the fly? Perhaps > > the power metering should be derived from a DSP based spectrum > > analyzer? > > > > Accept the fact that the power level control is relative. If > > Wayne and Lyle can improve on it that's great. However, trying > > to hold .1 dB or even 1 dB accuracy from 1 mW to 120 W, 1.8 MHz > > to 54 MHz with arbitrary modulation sources in a reasonably > > priced amateur transceiver is a fool's errand. > > > > 73, > > > >... Joe, W4TV > > > ___ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > 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: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
> If what Joe claims is true then this is a more serious issue > than even I imagined, since it affects SSB operation as well > as data modes. It would be so serious that I suspect he is > wrong about it. > > If I dial up 100W in SSB or data I expect the power to be > limited to 100W PEP, not 100W average power. The K3, like any other peak reading wattmeter uses a time constant appropriate for "normal" voice. As such in SSB the K3 adjusts for the typical peak to average of voice - one of the reasons for TXG VCE. Serious investigation will show that TXG VCE will vary with the particular voice and the level of compression (clipping) prior to the power control circuitry. Watching the output with a scope or fast peak reading wattmeter like the LP-100 will also show the differences (and deviations) with voice characteristics and compressions levels. However with digital modes like PSK31 the peak to average ratio varies with modulation and compression/clipping can not be tolerated if IMD is to be avoided. To be accurate with arbitrary digital modulation, the wattmeter must be able to respond to peaks in the fraction of a millisecond range. To adequately control the power level and must be able to predict the required peak to average ratio (headroom). In commercial applications (cellular telephone, digital TV, etc.) the power amplifiers are regularly operated at average power levels 10 to 20 dB OR MORE below saturation (the 1 dB compression point) with long time constant average power control due to the high peak to average ratios. > One reason I suspect he is wrong is that the observation of > getting around twice the requested power applies to any data > mode, not just PSK31. I can feed a pure sine wave in, request > a power of 5W, and get 10W out. If the K3 power meter was > indeed average level then it should still limit the power to > 5W as it does in SSB. No. If you were operating in SSB (and DATA A is SSB), the internal "adjustment" for peak to average in a voice signal would cause the gain in the amplifier chain to be increased to provide approximately twice the requested power output. I can create almost any arbitrary level of "overpower" for a single tone in DATA A simply by adjusting TXG VCE. If it is set (as I normally do) for +1.5 dB, I will see just about 3dB of "overpower" when driving the k3 with a single tone and adjusting the line input for five bars of ALC. If, on the other hand, I reduce TXG VCE to -1.5 dB, the power level will be almost exactly the requested level (15.8 for 15, 98 for 100 on 20 meters). This has nothing to do with the peak to average ratio since this is with tone ... only with the way the K3 controls power in SSB modes. Again, the K3 wattmeter is essentially average responding (as you would expect for CW and to be used with the tuner). The MCU then makes an "educated" guess bout the peak to average power and duty cycle in SSB. TXG VCE then allows the user to "tune" that adjustment for their own voice and level of compression. TXG VCE does not seem to effect the power level for a single tone in SSB (as expected) but it seems to have a significant effect in DATA A. That appears to be as expected if the power control is based on an average reading wattmeter with a compensation factor. Perhaps the MCU needs another control - TXG DTA anyone? By the way, AFSK A behaves exactly like SSB and does not show the "overpower" with tone. 73, ... Joe, W4TV > -Original Message- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Julian, G4ILO > Sent: Sunday, January 04, 2009 5:50 AM > To: elecraft@mailman.qth.net > Subject: RE: [Elecraft] K3: Still unable to set power > correctly in DATA A(sigh) > > > > > > AD6XY wrote: > > > > > > > > Joe Subich, W4TV-4 wrote: > >> > >> > >> Since the K3 power control is based on average power and not > >> instantaneous (absolute) peak power, the power level (both > >> requested and reported) can not be relied on as a gauge of > >> proper operation unless the user knows with certainty how much > >> headroom is required to handle the peak power without compression > >> or clipping. > >> > >> > > > > Unfortunately, the life of amplifier power transistors and > to a lesser > > extent valves is based on the peak power. Most license > conditions are > > also based on peak power. > > > > A power control based on average power is therefore, > irrespective of > > any technical merit, inappropriate. It is theoretically illegal in > > many countries to use with a following a
RE: [Elecraft] K3: Still unable to set power correctly in Data A(sigh)
One way to resolve the confusion over interpreting the K3's power output display would be to implement a peak reading/average reading feature, like that in the s-meter. The S-meter can show both peak and average signal strength simultaneously. Perhaps something like that could be done with the power output meter. I also like the suggestion to blink the red TX LED when the K3 is is in the test mode. I, too, often fail to note the LCD indicator. Jim W8ZR ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in Data A (sigh)
>Setting a power control calibrated for CW and expecting that level to be accurate for PSK31 or any other arbitrary digital modulation is complete folly and utter hubris. I also read another post that the K3 watt meter is an average power responding device and there in lies a problem of setting power for an arbitrary waveform that will not create IM products. In the old days we could use a monitor scope to make sure we weren't clipping. An interesting thought about a future K3 band scope is to provide a station monitor mode... I also wonder why the internal K3 wattmeter does not have a peak detecting mode and set the PEP power to the requested level. That doesn't take care of directional coupler errors but I suspect it would drop the complaint level down 6 dB. K3 output power vs. requested power has been a continuous theme on the reflector. What is wrong about setting and displaying peak envelope power or at least have the ability to switch to a peak detecting mode? It seems to me that if we are worried about IM products when approaching PA clipping levels that PEP is what we should be monitoring for any transmitted waveform. Mike Scott - AE6WA Tarzana, CA (DM04 / near LA) K3-100 #508/ KX1 #1311 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
Peter Connors, F5VNB wrote: > > Joe > > Thank you for pointing out the difficulties in setting average power > across a range of modulation types. > Whatever the peak/average ratio of the modulation, the output power from > the PA is peak limited - so wouldn't the answer be a K3 power meter and > power control that shows/sets peak rather than average power? That would certainly be the answer, and I suspect that if you took a poll of K3 owners, the majority would have thought that is what they already had. How close the actual power is to the level dialled up on the control is, within reason, a side issue. I think everyone would expect that the ALC of any transceiver to be capable of limiting the *peak* output power to below the point at which clipping occurs. If you have a front panel control that is linked to the ALC then it should also be able to limit the peak output power to any lower value. Whether the control has some arbitrary scale of 0 to 10 or an approximation of actual output power is really beside the point. Most amateur power meters only have a specification of within 10% FSD or something quite broad, and I don't think anyone expects the K3 to do better than that. My point is that one expects the power control to control the peak power, not the average power, because it is excessive peaks that cause splatter and violation of one's license conditions. To assert that every K3 owner needs an oscilliscope or laboratory grade peak reading meter in order to ensure that they never exceed a given peak power because the K3 internal circuits are incapable of doing so is a very serious criticism indeed. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in%2C-DATA-A%28sigh%29-tp2106764p2108826.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
AD6XY wrote: > > > > Joe Subich, W4TV-4 wrote: >> >> >> Since the K3 power control is based on average power and not >> instantaneous (absolute) peak power, the power level (both >> requested and reported) can not be relied on as a gauge of >> proper operation unless the user knows with certainty how much >> headroom is required to handle the peak power without compression >> or clipping. >> >> > > Unfortunately, the life of amplifier power transistors and to a lesser > extent valves is based on the peak power. Most license conditions are also > based on peak power. > > A power control based on average power is therefore, irrespective of any > technical merit, inappropriate. It is theoretically illegal in many > countries to use with a following amplifier as well as being likely to > result in damage to that PA. > > This is why it is such a serious issue and why we keep banging on about > it. > > Mike > > If what Joe claims is true then this is a more serious issue than even I imagined, since it affects SSB operation as well as data modes. It would be so serious that I suspect he is wrong about it. If I dial up 100W in SSB or data I expect the power to be limited to 100W PEP, not 100W average power. One reason I suspect he is wrong is that the observation of getting around twice the requested power applies to any data mode, not just PSK31. I can feed a pure sine wave in, request a power of 5W, and get 10W out. If the K3 power meter was indeed average level then it should still limit the power to 5W as it does in SSB. The issue here is not how the K3 power control works. It is that it is not working in DATA A as it does in SSB. DATA A ought simply to be treated as another SSB mode that just allows a different choice of audio input and filter settings. I believe that it did originally work like that in early versions of the firmware. Sorry to continue the topic after Wayne requested we call a halt on it, but the assertion made by Joe opens up a whole new can of worms if he is indeed correct about it. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in-DATA-A-%28sigh%29-tp2106260p2108786.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
Joe Subich, W4TV-4 wrote: > > > Since the K3 power control is based on average power and not > instantaneous (absolute) peak power, the power level (both > requested and reported) can not be relied on as a gauge of > proper operation unless the user knows with certainty how much > headroom is required to handle the peak power without compression > or clipping. > > 73, > >... Joe, W4TV > > Unfortunately, the life of amplifier power transistors and to a lesser extent valves is based on the peak power. Most license conditions are also based on peak power. A power control based on average power is therefore, irrespective of any technical merit, inappropriate. It is theoretically illegal in many countries to use with a following amplifier as well as being likely to result in damage to that PA. This is why it is such a serious issue and why we keep banging on about it. Mike -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in-DATA-A-%28sigh%29-tp2106260p2108740.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
Joe Thank you for pointing out the difficulties in setting average power across a range of modulation types. Whatever the peak/average ratio of the modulation, the output power from the PA is peak limited - so wouldn't the answer be a K3 power meter and power control that shows/sets peak rather than average power? The power control would then be set just once and the average power would be an unavoidable consequence of the choice of modulation. 73, Pete F5VNB Joe Subich, W4TV wrote: Setting a power control calibrated for CW and expecting that level to be accurate for PSK31 or any other arbitrary digital modulation is complete folly and utter hubris. Among other issues the wattmeter does not know if you are setting peak or average power and it does not know what the average power should be for the arbitrary data and arbitrary modulation. For the K3 to accurately control the power level in all modes the its directional coupler would probably need to be improved by at least an order or magnitude. The response flatness would need to be improved by at least an octave and the detectors would need to be substantially more linear ... and that's just for CW. To handle arbitrary audio inputs takes some knowledge of the peak to average ratio as well as the peak duration (duty cycle) in order to select the proper detector time constants. Every voice every digital mode and every arbitrary data stream will have different peak to average ratios and duty cycles. Do you expect the DSP to calculate those values on the fly? Perhaps the power metering should be derived from a DSP based spectrum analyzer? Accept the fact that the power level control is relative. If Wayne and Lyle can improve on it that's great. However, trying to hold .1 dB or even 1 dB accuracy from 1 mW to 120 W, 1.8 MHz to 54 MHz with arbitrary modulation sources in a reasonably priced amateur transceiver is a fool's errand. 73, ... Joe, W4TV ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
Joe Subich, W4TV-4 wrote: > > > > Perhaps > the power metering should be derived from a DSP based spectrum > analyzer? > > Accept the fact that the power level control is relative. If > Wayne and Lyle can improve on it that's great. However, trying > to hold .1 dB or even 1 dB accuracy from 1 mW to 120 W, 1.8 MHz > to 54 MHz with arbitrary modulation sources in a reasonably > priced amateur transceiver is a fool's errand. > > [SNIP] > > I never measure power using the power meter on the K3, I always use an oscilloscope as that will read the true power and not rely on that silly little meter on the rig which is never correct and I've never had a problem like that. -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in%2C-DATA-A%28sigh%29-tp2106764p2108569.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
> > Rich VE3KI posted some measurements done with the PSKMeter > that show poor IMD above about 50W. The K3 wattmeter is essentially an average responding device. PSK31 has a relatively high peak to average ratio ... as much as 6 dB or more depending on the particular data but generally running at least 3 dB at idle. Since the KPA3 will clip at an output power much above 110 watts, indicated power output on PSK31 idle should never exceed 50 watts with 30 to 40 watts being a "safe" value. > I've suggested he re-run the tests with a 3dB pad to compare > apples-to-apples and reduce the effect of non-linear response > in the PSKMeter, but Rich has suggested that perhaps the peak > power is exceeding 100W when the TX PWR setting is above 50W. I've made similar measurements to those of VE3KI using a soundcard and software detectors on a separate receiver while monitoring the K3 power output with a factory calibrated LP-100. In fact, the K3's peak power output is around 110 watts when the indicated (average) power is about 50 watts with PSK31 idle modulation. Increasing the power output simply results in extreme overdrive of the KPA3 (and/or the IPA since I did not make separate measurements below the 12 watt level). The excess drive results in a higher average power output due to clipping in the amplifier chain. The clipping results in greatly increased IMD products. Similar sets of measurements should be made for EVERY digital mode - particularly modes that use phase shift and/or multi-tone modulation. Every one of those modes will have unique peak to average ratios and duty cycles. Increasing the power output beyond the point of peak clipping (more specifically the 1 dB compression point) will, at best, only cause IMD and interference to other users and will, at worst, result in decoding errors in reception. Since the K3 power control is based on average power and not instantaneous (absolute) peak power, the power level (both requested and reported) can not be relied on as a gauge of proper operation unless the user knows with certainty how much headroom is required to handle the peak power without compression or clipping. 73, ... Joe, W4TV > -Original Message- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Leigh > L. Klotz, Jr WA5ZNU > Sent: Saturday, January 03, 2009 4:03 PM > To: Julian, G4ILO > Cc: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3: Still unable to set power > correctly in DATA A(sigh) > > > There's a thread on a related topic (PSK TX IMD) on the > Elecraft K3 list > at Yahoo Groups. > Rich VE3KI posted some measurements done with the PSKMeter that show > poor IMD above about 50W. > I've suggested he re-run the tests with a 3dB pad to compare > apples-to-apples and reduce the effect of non-linear response in the > PSKMeter, but Rich has suggested that perhaps the peak power is > exceeding 100W when the TX PWR setting is above 50W. Your > observations > would seem to confirm that. > > Leigh/WA5ZNU > > I recently installed the latest firmware and ran the TX Power > > calibration wizard - nice work. However while running WSPR (a sound > > card data mode) I was somewhat annoyed to find the K3 power meter > > showing about twice the output power I had selected. Checks > using my > > own power meter confirmed that the K3 is putting out about > twice the > > amount of power specified by the power control when DATA A is used > > (though the exact difference seems to vary a bit from band to band.) > > > > Using TXG VCE is NOT the answer, as the output power in SSB (and in > > CW) is regulated correctly. Using the maximum TXG VCE > -3.0dB I still > > can't quite get the power down to what it should be, but if > I do that, > > SSB output is too low. > > > > Forgive the note of frustration but I am frankly very > annoyed and fed > > up that after all this time and numerous reports of this > issue from me > > and several other people going back several months, the K3 is still > > not capable of performing a simple basic function like > regulating the > > output power to the level the operator requests. I am seriously > > considering selling the K3 at this point, as I am losing confidence > > that Elecraft has any intention of fixing this issue. > > > > - > > Julian, G4ILO. K2 #392 K3 #222. > > http://www.g4ilo.com/ G4ILO's Shack > http://www.ham-directory.com/ Ham > > Directoryhttp://www.g4ilo.com/kcomm.html KComm for > Elecraft K2 and K3 > > > > __
RE: [Elecraft] K3: Still unable to set power correctly in, DATA A(sigh)
> The point is it was providing the correct power output levels > before the last couple of firmware revisions. Something > changed that made it go from putting out approximately the > right power level, to putting out WAY TOO MUCH (i.e. causing > splatter) power. Not true ... in spite of careful calibration at both 5 and 50 watt levels neither of my K3s has ever produced exactly the power requested on any band other than 20 meters, on any mode other than CW and at any power other than 5 or 50 watts. The variations can be as much as 3 dB on SSB depending on the peak to average ratio of the driving audio and amount of compression used. Setting a power control calibrated for CW and expecting that level to be accurate for PSK31 or any other arbitrary digital modulation is complete folly and utter hubris. Among other issues the wattmeter does not know if you are setting peak or average power and it does not know what the average power should be for the arbitrary data and arbitrary modulation. For the K3 to accurately control the power level in all modes the its directional coupler would probably need to be improved by at least an order or magnitude. The response flatness would need to be improved by at least an octave and the detectors would need to be substantially more linear ... and that's just for CW. To handle arbitrary audio inputs takes some knowledge of the peak to average ratio as well as the peak duration (duty cycle) in order to select the proper detector time constants. Every voice every digital mode and every arbitrary data stream will have different peak to average ratios and duty cycles. Do you expect the DSP to calculate those values on the fly? Perhaps the power metering should be derived from a DSP based spectrum analyzer? Accept the fact that the power level control is relative. If Wayne and Lyle can improve on it that's great. However, trying to hold .1 dB or even 1 dB accuracy from 1 mW to 120 W, 1.8 MHz to 54 MHz with arbitrary modulation sources in a reasonably priced amateur transceiver is a fool's errand. 73, ... Joe, W4TV > -Original Message- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Steve Ward > Sent: Saturday, January 03, 2009 2:54 PM > To: elecraft@mailman.qth.net > Subject: [Elecraft] K3: Still unable to set power correctly > in, DATA A(sigh) > > > "Joe Subich, W4TV" Wrote: > > >So? Reduce the power you request to get the required output. > >What other radio has a "calibrated" power output control? > > >The wattmeter in the K3 is relative ... there is a documented > >power vs. frequency slope. Testing seems to indicate there > >are also nonlinearities with changes in peak to average ratio > >and as the power level moves away from the calibration points. > >The directional coupler in the K3 does not have the high level > >of directivity and compensation of a product like the Telepost > >LP-100 nor does it have the high quality detectors. > > >If you want a bloody laboratory grade meter, buy a laboratory > >grade power meter. > > The point is it was providing the correct power output levels > before the last couple of firmware revisions. Something > changed that made it go from putting out approximately the > right power level, to putting out WAY TOO MUCH (i.e. causing > splatter) power. > > Setting TXG VCE to -3 dB gets DATA A output almost to where > it should be, but of course adversely affects SSB. > > This is NOT about the accuracy of the wattmeter, its about > overdriving the PA. > > 73, > Steve > AD7OG > K3 #1544 > > ___ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > 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: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in DATA A (sigh)
Leigh L. Klotz Jr WA5ZNU wrote: > > There's a thread on a related topic (PSK TX IMD) on the Elecraft K3 list > at Yahoo Groups. > Rich VE3KI posted some measurements done with the PSKMeter that show > poor IMD above about 50W. > I've suggested he re-run the tests with a 3dB pad to compare > apples-to-apples and reduce the effect of non-linear response in the > PSKMeter, but Rich has suggested that perhaps the peak power is > exceeding 100W when the TX PWR setting is above 50W. Your observations > would seem to confirm that. > > I don't do Yahoo so I haven't seen that thread, but I observed exactly the same phenomenon using my KK7UQ IMD meter. However it is blatantly obvious that the K3 is putting out too much power when this occurs, because its own power meter shows this. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in-DATA-A-%28sigh%29-tp2106260p2107291.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
Joe Subich, W4TV-4 wrote: > > > So? Reduce the power you request to get the required output. > What other radio has a "calibrated" power output control? > > If you want a bloody laboratory grade meter, buy a laboratory > grade power meter. > > Er, my K2 has always been able to do this. My FT-817 will also not put out more than the power level requested. Nobody has asked for laboratory grade standard of accuracy. But a radio that puts out 10W when 5W is requested clearly has a design fault, especially when it is demonstrably capable of regulating the power correctly in other modes (though private mail suggests that certain people aren't happy with the repeatability of the SSB level control either.) - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/K3%3A-Still-unable-to-set-power-correctly-in-DATA-A-%28sigh%29-tp2106260p2107232.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in DATA A (sigh)
There's a thread on a related topic (PSK TX IMD) on the Elecraft K3 list at Yahoo Groups. Rich VE3KI posted some measurements done with the PSKMeter that show poor IMD above about 50W. I've suggested he re-run the tests with a 3dB pad to compare apples-to-apples and reduce the effect of non-linear response in the PSKMeter, but Rich has suggested that perhaps the peak power is exceeding 100W when the TX PWR setting is above 50W. Your observations would seem to confirm that. Leigh/WA5ZNU I recently installed the latest firmware and ran the TX Power calibration wizard - nice work. However while running WSPR (a sound card data mode) I was somewhat annoyed to find the K3 power meter showing about twice the output power I had selected. Checks using my own power meter confirmed that the K3 is putting out about twice the amount of power specified by the power control when DATA A is used (though the exact difference seems to vary a bit from band to band.) Using TXG VCE is NOT the answer, as the output power in SSB (and in CW) is regulated correctly. Using the maximum TXG VCE -3.0dB I still can't quite get the power down to what it should be, but if I do that, SSB output is too low. Forgive the note of frustration but I am frankly very annoyed and fed up that after all this time and numerous reports of this issue from me and several other people going back several months, the K3 is still not capable of performing a simple basic function like regulating the output power to the level the operator requests. I am seriously considering selling the K3 at this point, as I am losing confidence that Elecraft has any intention of fixing this issue. - Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
> > So? Reduce the power you request to get the required output. > What other radio has a "calibrated" power output control? > > The wattmeter in the K3 is relative ... there is a documented > power vs. frequency slope. Testing seems to indicate there > are also nonlinearities with changes in peak to average ratio > and as the power level moves away from the calibration points. > The directional coupler in the K3 does not have the high level > of directivity and compensation of a product like the Telepost > LP-100 nor does it have the high quality detectors. > > If you want a bloody laboratory grade meter, buy a laboratory > grade power meter. > > > > I'm sorry, but profanities end the conversation for me. I was merely pointing out that something has changed. 73 Stephen G4SJP ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] K3: Still unable to set power correctly in DATA A(sigh)
> I can report the identical problem to that which Julian > describes. I don't remember the firmware version where this > started but it was certainly not always the case that the > actual power output in Data A mode was so much greater than > the requested power. I can set for 5W and get a displayed (K3 > meter) output in excess of 10W. No problems at all with the > other modes that I have tried. So? Reduce the power you request to get the required output. What other radio has a "calibrated" power output control? The wattmeter in the K3 is relative ... there is a documented power vs. frequency slope. Testing seems to indicate there are also nonlinearities with changes in peak to average ratio and as the power level moves away from the calibration points. The directional coupler in the K3 does not have the high level of directivity and compensation of a product like the Telepost LP-100 nor does it have the high quality detectors. If you want a bloody laboratory grade meter, buy a laboratory grade power meter. > -Original Message- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Stephen Prior > Sent: Saturday, January 03, 2009 11:45 AM > To: elecraft > Subject: Re: [Elecraft] K3: Still unable to set power > correctly in DATA A(sigh) > > > I can report the identical problem to that which Julian > describes. I don't remember the firmware version where this > started but it was certainly not always the case that the > actual power output in Data A mode was so much greater than > the requested power. I can set for 5W and get a displayed (K3 > meter) output in excess of 10W. No problems at all with the > other modes that I have tried. > > Stephen G4SJP > > > On 03/01/2009 16:36, "Julian, G4ILO" wrote: > > > > > > > I recently installed the latest firmware and ran the TX Power > > calibration wizard - nice work. However while running WSPR (a sound > > card data mode) I was somewhat annoyed to find the K3 power meter > > showing about twice the output power I had selected. Checks > using my > > own power meter confirmed that the K3 is putting out about > twice the > > amount of power specified by the power control when DATA A is used > > (though the exact difference seems to vary a bit from band to band.) > > > > Using TXG VCE is NOT the answer, as the output power in SSB (and in > > CW) is regulated correctly. Using the maximum TXG VCE > -3.0dB I still > > can't quite get the power down to what it should be, but if > I do that, > > SSB output is too low. > > > > Forgive the note of frustration but I am frankly very > annoyed and fed > > up that after all this time and numerous reports of this > issue from me > > and several other people going back several months, the K3 is still > > not capable of performing a simple basic function like > regulating the > > output power to the level the operator requests. I am seriously > > considering selling the K3 at this point, as I am losing confidence > > that Elecraft has any intention of fixing this issue. > > > > - > > Julian, G4ILO. K2 #392 K3 #222. > > http://www.g4ilo.com/ G4ILO's Shack > http://www.ham-directory.com/ Ham > > Directoryhttp://www.g4ilo.com/kcomm.html KComm for > Elecraft K2 and K3 > > > > ___ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > 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: Elecraft@mailman.qth.net 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
Re: [Elecraft] K3: Still unable to set power correctly in DATA A (sigh)
I can report the identical problem to that which Julian describes. I don't remember the firmware version where this started but it was certainly not always the case that the actual power output in Data A mode was so much greater than the requested power. I can set for 5W and get a displayed (K3 meter) output in excess of 10W. No problems at all with the other modes that I have tried. Stephen G4SJP On 03/01/2009 16:36, "Julian, G4ILO" wrote: > > > I recently installed the latest firmware and ran the TX Power calibration > wizard - nice work. However while running WSPR (a sound card data mode) I > was somewhat annoyed to find the K3 power meter showing about twice the > output power I had selected. Checks using my own power meter confirmed that > the K3 is putting out about twice the amount of power specified by the power > control when DATA A is used (though the exact difference seems to vary a bit > from band to band.) > > Using TXG VCE is NOT the answer, as the output power in SSB (and in CW) is > regulated correctly. Using the maximum TXG VCE -3.0dB I still can't quite > get the power down to what it should be, but if I do that, SSB output is too > low. > > Forgive the note of frustration but I am frankly very annoyed and fed up > that after all this time and numerous reports of this issue from me and > several other people going back several months, the K3 is still not capable > of performing a simple basic function like regulating the output power to > the level the operator requests. I am seriously considering selling the K3 > at this point, as I am losing confidence that Elecraft has any intention of > fixing this issue. > > - > Julian, G4ILO. K2 #392 K3 #222. > http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham > Directoryhttp://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
