Re: [Elecraft] K3 output power spikes
On Tue,3/1/2016 12:54 PM, Bill Frantz wrote: I have not noticed any RF noise on receive when I put it into "always on" mode. Hi Bill, This is quite interesting to me. I run SO2R, so I would be concerned about noise in the second radio while transmitting on the first. Do you have a way to check this? A second radio that can listen on other bands/antennas for weak signals while your tranmitting? Thanks and 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] K3 output power spikes
FWIW, I power my barefoot K3 with batteries and a solar charger. After our club county expedition for the California QSO Party (CQP) last year, I had a new appreciation for the way low power supply voltage could make a clean transmitter dirty. To address this problem at home, I got a N8XJK Boost Regulator from TGE. This device boosts the battery voltage to the radio. Mine shows 13.9 volts, receive and 13.4 volts key down at 100W on 160M. I normally have it set up to only boost voltage when is senses RF output from the transmitter. (I need to talk on SSB before it cuts in.) I have not noticed any RF noise on receive when I put it into "always on" mode. For a single radio setup, any RF noise it might make will be completely masked during transmit. We'll see how it works in multi-transmitter setups when I take to next year's CQP. 73 Bill AE6JV --- Bill Frantz| Ham radio contesting is a| Periwinkle (408)356-8506 | contact sport. | 16345 Englewood Ave www.pwpconsult.com | - Ken Widelitz K6LA / VY2TT | Los Gatos, CA 95032 __ 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] K3 output power spikes
If a power supply sags when lots of power is being drawn, it will affect whatever is trying to draw the power. For a transmitter / amplifier, that means the output power is most likely going to sag as well. The extent of the sag is directly related to how much the power supply sags, which, of course, depends on how well it is regulated. For the K3, we recommend well regulated power supplies with short supply leads. If the supply is rock solid and well regulated, you should see little voltage drop. Likewise, if you are using short, large wires from the supply to the K3, you will lose little power in that link. Remember that there is power loss in cable, and long skinny conductors will heat up and lose more power due to IIR losses than short fat wires. The K3 will try to correct power output variations, but if the supply / cabling problems won’t allow that, then it cannot. At the same time, it is quite possible the original poster needs to rework his power calibration (again). He had a major change in the components in his transceiver, and over time and use they will age and cause changes. For him, I suggest talking to customer support. The second area is the KPA500. The HV supply is not heavily regulated, by design. It has a pair of very large capacitors on the supply, but when high power is being drawn, the output voltage will sag. This is quite normal. Thus at the start of a transmission the voltage will be high, as will transmitted output power, then will quickly sag to the nominal output value. This can also be affected by power cabling. Some operators may see more sag than they should due to long power cables. We usually see this with amplifiers plugged into 120V outlets. Make sure your 120V cable is large and as short as possible, AND make sure the 120V wall cabling is likewise large. I believe the NEC specifies 12 gauge wire for outlets, my experience with that size is very good. If you can use a 240V supply for the KPA, then it is much better. As pointed out above, power losses in wire is I*I*R. Since current will be dropped in half when using 240V over 120, the cable power losses will be one-quarter with 240 when compared to 120V. Perhaps it might be time for some of us to perform their annual system check and maintenance, starting with the shack power supply? I’ll start this round with my own station today! - Jack Brindle, W6FB > On Mar 1, 2016, at 7:17 AM, Jim Sheldon wrote: > > Thanks David for posting this. I noticed this from time to time with my old > K3 and now also with the new K3S. I keep the KPA500 output set to around > 400-450 watts most of the time and notice spikes to 550 or so on the first or > second dit when sending CW at times. I just built the kit and have done the > TX calibrations properly and they all passed via the Utility program. > > I'm using the factory supplied #12 gauge power cable and the power supply is > a pretty well regulated MFJ 4245MV switcher (RFI quiet here). This supply is > adjustable and evidently the meter isn't totally accurate or there is a > larger voltage drop in the cable than I thought there should be. I checked > the K3S' meter display after receiving this email and it read 13.2 volts. > Keyed to 13.8 volts on the meter, but at 20 watts out, driving the amplifier, > it dropped to 12.6 volts while keyed. > > In line with your findings, I set the MFJ supply to read 13.8 volts on the > K3S display and it now only drops to 13.3 volts under the 20 watt load. The > occasional power spikes seem to have disappeared, so it's something everyone > should take a look at if they do experience the power spike problem. > > Again, thanks for posting this David. > > Jim - W0EB > Park City, KS > > -- Original Message -- > From: "David via Elecraft" > To: elecraft@mailman.qth.net > Sent: 3/1/2016 5:40:46 AM > Subject: Re: [Elecraft] K3 output power spikes > >> My K3 s/n 4487 has exhibited similar behaviour since I built it in 2010. >> Despite calls to Elecraft Support no solution was found despite Gary talking >> me through various items until a month or so ago when the spike was causing >> problems with my amp on 24 Mhz. It was mentioned that the K3 must see 13 >> volts whenever it is transmitting and to check this on the front panel by >> tapping the Display button. Mine showed 13.6 volts on receive and 12.6 volts >> on Tx. Turned out my old power supply regulation was faulty. Anyway after a >> power supply rebuild and further check it now shows 13.6 volts on receive >> and 13.3 volts on Tx at 100 watts output. A further TX calibration completed >> the process and so far no power spikes! So check your power supply is >> supplying sufficient voltage on key down. >> >> Dave G0AIX >> &g
Re: [Elecraft] K3 output power spikes
For what it's worth, I've found over the years that battery power is less innocent than you'd think when powering electronics. Especially on a tired or cheap battery with a high internal resistance - those can drop a surprising amount of voltage under load with unexpected timing, etc. even when fully charged and not heavily loaded. This can really wreak havoc with things that need well-regulated steady power... So I'd agree that this should probably be trouble-shot on a good power supply. The spiking behavior may not be something fully within Elecraft's control... 73, LS W5QD -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-output-power-spikes-tp7614763p7614789.html Sent from the Elecraft mailing list archive at Nabble.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] K3 output power spikes
I thought that one of the features of the K3/K3s was that it was able to run, and run well, off of batteries. These power spikes makes it sound like that is not the case? Or am I missing something? Batteries start out at 12.6v and go down from there. The K3/K3s needs to run well down to something like 10.5 to 11v. But if they need at least 13v to prevent power spikes . . . . 73 de dave ab9ca/4 On 3/1/16 9:30 AM, Don Wilhelm wrote: Bill, Is there any way that you can increase the power supply voltage to 13.0 volts or more during transmit? If so, that should help. Most of my experience with power control is with the K2 which starts out at lower than the requested power after a band change or a change in power level, but quickly builds up to the requested power. The result is a lack of power spikes. I figured that the K3 power control is similar, and if so, I would not expect power spikes at all. Perhaps the power control loop should be investigated for critical damping. If power spikes occur, that is an indication that the control loop is underdamped. If the control loop damping is the problem, it is possible that this is not a problem for all K3s - the loop gain will may vary depending on the gain of the transmit RF stages, and while one K3 may have this problem, another may not (that is the case with the K2). The RF Gain also varies from band to band, so there may be a difference in that behavior depending on what band is used. 73, Don W3FPR On 3/1/2016 10:12 AM, Bill Hammond via Elecraft wrote: Hi John, My power dances all over the place (my serial number is 00069). Just had a quick QSO with the KPA500 indicating 560 watts at the beginning and then going down to 480 at the end. That is typical. My 12 volt supply drops to 12.2 on transmit, 13.3 on receive. I have a long 12 volt cable from the supply so “I" squared losses are understandable in the cable. Driving power from the K3 is variable per band but typically set to 25 watts or so. The QSO described above was on 17 Meters and the drive is 25 watts there for ~500 watts out or just below after stabilization. __ 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 ho13d...@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] K3 output power spikes
Bill, Is there any way that you can increase the power supply voltage to 13.0 volts or more during transmit? If so, that should help. Most of my experience with power control is with the K2 which starts out at lower than the requested power after a band change or a change in power level, but quickly builds up to the requested power. The result is a lack of power spikes. I figured that the K3 power control is similar, and if so, I would not expect power spikes at all. Perhaps the power control loop should be investigated for critical damping. If power spikes occur, that is an indication that the control loop is underdamped. If the control loop damping is the problem, it is possible that this is not a problem for all K3s - the loop gain will may vary depending on the gain of the transmit RF stages, and while one K3 may have this problem, another may not (that is the case with the K2). The RF Gain also varies from band to band, so there may be a difference in that behavior depending on what band is used. 73, Don W3FPR On 3/1/2016 10:12 AM, Bill Hammond via Elecraft wrote: Hi John, My power dances all over the place (my serial number is 00069). Just had a quick QSO with the KPA500 indicating 560 watts at the beginning and then going down to 480 at the end. That is typical. My 12 volt supply drops to 12.2 on transmit, 13.3 on receive. I have a long 12 volt cable from the supply so “I" squared losses are understandable in the cable. Driving power from the K3 is variable per band but typically set to 25 watts or so. The QSO described above was on 17 Meters and the drive is 25 watts there for ~500 watts out or just below after stabilization. __ 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] K3 output power spikes
Not to worry, my K3S does it too :-( On Mar 1, 2016, at 8:12 AM, Bill Hammond via Elecraft wrote: > Hi John, > My power dances all over the place (my serial number is 00069). Just had a > quick QSO with the KPA500 indicating 560 watts at the beginning and then > going down to 480 at the end. That is typical. My 12 volt supply drops to > 12.2 on transmit, 13.3 on receive. I have a long 12 volt cable from the > supply so “I" squared losses are understandable in the cable. Driving power > from the K3 is variable per band but typically set to 25 watts or so. The > QSO described above was on 17 Meters and the drive is 25 watts there for ~500 > watts out or just below after stabilization. > > I remember the power fluctuation issue being discussed years ago on this > reflector and it was explained that the power control uses a sampling and > feedback loop that takes “time” to stabilize. That said, I believe we are > both experiencing some power fluctuation over 10% in a short period of time. > Depending on the amplifiers we are using this could cause real downstream > issues, like distorted signals, spurs or alarm faulting of smart amplifiers. > > Could we have some aging component that is aggravating this issue? Our K3’s > are among the oldest on the air. > > 73, > Bill-AK5X > > > >> On Feb 29, 2016, at 2:24 PM, John K1JD wrote: >> >> Hi All, >> My K3 SN #071 was purchased new November 2007. It’s had a few mods/upgrades >> along the way and its firmware is current. >> >> Last Field Day 2015 at W5YA, the K3’s LPA failed after a close lightning >> strike. I was able to successfully repair the LPA replacing both discrete >> and SMD components. Performed a Pout calibration using the K3 Utility >> program afterward and it passed. >> >> My 9500 amplifier (driven by the K3) has had a few instances of a high plate >> current faults since new in December 2010. These faults had been infrequent >> enough to ignore. More recently though the problems have been occurring more >> often. Swapping the tube did not help nor did careful inspection inside the >> amplifier reveal anything. >> >> Evidence that the problem is related to the K3 and not the amplifier >> presented itself by accident a few days ago. I had the K3’s output set to >> 40w and the Alpha was off. I inadvertently bumped the key and noted an >> instantaneous output of 54w on the Powermaster II wattmeter. A few more >> dits, and the power output settled back to 40w. Hmmm… if the amplifier had >> been in line, the K3’s drive set for full legal limit and a first dit >> resulted in an additional 30% drive, a high plate current fault might >> certainly happen. >> >> This morning I was using the KPA500 amp with my K3’s power set to 28 watts. >> After an early AM CW fix I left the station on, walked away and came back in >> a few hours hours. On first dit the KPA’s instantaneous power showed 650w on >> the Powermaster II and illuminated a red LED on the KPA500, then settled >> back down to <500w. >> >> OK, so it IS the K3 causing the problem BUT the power output spikes occur >> very infrequently. It’s difficult to nail down the cause or even the >> conditions under which the problem is most likely to occur. >> >> Reading the archives, others have had power spike issues over the years. Is >> there a known fix? I’ve looked briefly at Elecraft’s alerts and mods but >> nothing jumps out. >> >> 73, >> John K1JD >> Santa Fe, NM >> >> >> >> >> __ >> 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 wham...@aol.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 w...@triconet.org __ 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] K3 output power spikes
Thanks David for posting this. I noticed this from time to time with my old K3 and now also with the new K3S. I keep the KPA500 output set to around 400-450 watts most of the time and notice spikes to 550 or so on the first or second dit when sending CW at times. I just built the kit and have done the TX calibrations properly and they all passed via the Utility program. I'm using the factory supplied #12 gauge power cable and the power supply is a pretty well regulated MFJ 4245MV switcher (RFI quiet here). This supply is adjustable and evidently the meter isn't totally accurate or there is a larger voltage drop in the cable than I thought there should be. I checked the K3S' meter display after receiving this email and it read 13.2 volts. Keyed to 13.8 volts on the meter, but at 20 watts out, driving the amplifier, it dropped to 12.6 volts while keyed. In line with your findings, I set the MFJ supply to read 13.8 volts on the K3S display and it now only drops to 13.3 volts under the 20 watt load. The occasional power spikes seem to have disappeared, so it's something everyone should take a look at if they do experience the power spike problem. Again, thanks for posting this David. Jim - W0EB Park City, KS -- Original Message -- From: "David via Elecraft" To: elecraft@mailman.qth.net Sent: 3/1/2016 5:40:46 AM Subject: Re: [Elecraft] K3 output power spikes My K3 s/n 4487 has exhibited similar behaviour since I built it in 2010. Despite calls to Elecraft Support no solution was found despite Gary talking me through various items until a month or so ago when the spike was causing problems with my amp on 24 Mhz. It was mentioned that the K3 must see 13 volts whenever it is transmitting and to check this on the front panel by tapping the Display button. Mine showed 13.6 volts on receive and 12.6 volts on Tx. Turned out my old power supply regulation was faulty. Anyway after a power supply rebuild and further check it now shows 13.6 volts on receive and 13.3 volts on Tx at 100 watts output. A further TX calibration completed the process and so far no power spikes! So check your power supply is supplying sufficient voltage on key down. Dave G0AIX --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto: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] K3 output power spikes
Hi John, My power dances all over the place (my serial number is 00069). Just had a quick QSO with the KPA500 indicating 560 watts at the beginning and then going down to 480 at the end. That is typical. My 12 volt supply drops to 12.2 on transmit, 13.3 on receive. I have a long 12 volt cable from the supply so “I" squared losses are understandable in the cable. Driving power from the K3 is variable per band but typically set to 25 watts or so. The QSO described above was on 17 Meters and the drive is 25 watts there for ~500 watts out or just below after stabilization. I remember the power fluctuation issue being discussed years ago on this reflector and it was explained that the power control uses a sampling and feedback loop that takes “time” to stabilize. That said, I believe we are both experiencing some power fluctuation over 10% in a short period of time. Depending on the amplifiers we are using this could cause real downstream issues, like distorted signals, spurs or alarm faulting of smart amplifiers. Could we have some aging component that is aggravating this issue? Our K3’s are among the oldest on the air. 73, Bill-AK5X > On Feb 29, 2016, at 2:24 PM, John K1JD wrote: > > Hi All, > My K3 SN #071 was purchased new November 2007. It’s had a few mods/upgrades > along the way and its firmware is current. > > Last Field Day 2015 at W5YA, the K3’s LPA failed after a close lightning > strike. I was able to successfully repair the LPA replacing both discrete and > SMD components. Performed a Pout calibration using the K3 Utility program > afterward and it passed. > > My 9500 amplifier (driven by the K3) has had a few instances of a high plate > current faults since new in December 2010. These faults had been infrequent > enough to ignore. More recently though the problems have been occurring more > often. Swapping the tube did not help nor did careful inspection inside the > amplifier reveal anything. > > Evidence that the problem is related to the K3 and not the amplifier > presented itself by accident a few days ago. I had the K3’s output set to 40w > and the Alpha was off. I inadvertently bumped the key and noted an > instantaneous output of 54w on the Powermaster II wattmeter. A few more dits, > and the power output settled back to 40w. Hmmm… if the amplifier had been in > line, the K3’s drive set for full legal limit and a first dit resulted in an > additional 30% drive, a high plate current fault might certainly happen. > > This morning I was using the KPA500 amp with my K3’s power set to 28 watts. > After an early AM CW fix I left the station on, walked away and came back in > a few hours hours. On first dit the KPA’s instantaneous power showed 650w on > the Powermaster II and illuminated a red LED on the KPA500, then settled back > down to <500w. > > OK, so it IS the K3 causing the problem BUT the power output spikes occur > very infrequently. It’s difficult to nail down the cause or even the > conditions under which the problem is most likely to occur. > > Reading the archives, others have had power spike issues over the years. Is > there a known fix? I’ve looked briefly at Elecraft’s alerts and mods but > nothing jumps out. > > 73, > John K1JD > Santa Fe, NM > > > > > __ > 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 wham...@aol.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] K3 output power spikes
I've noticed that the first time I TX with my KPA500 it will fault. Seems to settle down after that. May also spoke after band change. Sent from my iPhone ...nr4c. bill > On Mar 1, 2016, at 12:23 AM, Vic Rosenthal wrote: > > Hi john, > I think I've seen this myself. I would redo the power calibration with the K3 > utility and a good dummy load. I'm interested in hearing people's responses > to your question. > > Vic 4X6GP > >> On 29 Feb 2016, at 10:24 PM, John K1JD wrote: >> >> Hi All, >> My K3 SN #071 was purchased new November 2007. It’s had a few mods/upgrades >> along the way and its firmware is current. >> >> Last Field Day 2015 at W5YA, the K3’s LPA failed after a close lightning >> strike. I was able to successfully repair the LPA replacing both discrete >> and SMD components. Performed a Pout calibration using the K3 Utility >> program afterward and it passed. >> >> My 9500 amplifier (driven by the K3) has had a few instances of a high plate >> current faults since new in December 2010. These faults had been infrequent >> enough to ignore. More recently though the problems have been occurring more >> often. Swapping the tube did not help nor did careful inspection inside the >> amplifier reveal anything. >> >> Evidence that the problem is related to the K3 and not the amplifier >> presented itself by accident a few days ago. I had the K3’s output set to >> 40w and the Alpha was off. I inadvertently bumped the key and noted an >> instantaneous output of 54w on the Powermaster II wattmeter. A few more >> dits, and the power output settled back to 40w. Hmmm… if the amplifier had >> been in line, the K3’s drive set for full legal limit and a first dit >> resulted in an additional 30% drive, a high plate current fault might >> certainly happen. >> >> This morning I was using the KPA500 amp with my K3’s power set to 28 watts. >> After an early AM CW fix I left the station on, walked away and came back in >> a few hours hours. On first dit the KPA’s instantaneous power showed 650w on >> the Powermaster II and illuminated a red LED on the KPA500, then settled >> back down to <500w. >> >> OK, so it IS the K3 causing the problem BUT the power output spikes occur >> very infrequently. It’s difficult to nail down the cause or even the >> conditions under which the problem is most likely to occur. >> >> Reading the archives, others have had power spike issues over the years. Is >> there a known fix? I’ve looked briefly at Elecraft’s alerts and mods but >> nothing jumps out. >> >> 73, >> John K1JD >> Santa Fe, __ 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] K3 output power spikes
My K3 s/n 4487 has exhibited similar behaviour since I built it in 2010. Despite calls to Elecraft Support no solution was found despite Gary talking me through various items until a month or so ago when the spike was causing problems with my amp on 24 Mhz. It was mentioned that the K3 must see 13 volts whenever it is transmitting and to check this on the front panel by tapping the Display button. Mine showed 13.6 volts on receive and 12.6 volts on Tx. Turned out my old power supply regulation was faulty. Anyway after a power supply rebuild and further check it now shows 13.6 volts on receive and 13.3 volts on Tx at 100 watts output. A further TX calibration completed the process and so far no power spikes! So check your power supply is supplying sufficient voltage on key down. Dave G0AIX -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-output-power-spikes-tp7614763p7614778.html Sent from the Elecraft mailing list archive at Nabble.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] K3 output power spikes
Hi john, I think I've seen this myself. I would redo the power calibration with the K3 utility and a good dummy load. I'm interested in hearing people's responses to your question. Vic 4X6GP > On 29 Feb 2016, at 10:24 PM, John K1JD wrote: > > Hi All, > My K3 SN #071 was purchased new November 2007. It’s had a few mods/upgrades > along the way and its firmware is current. > > Last Field Day 2015 at W5YA, the K3’s LPA failed after a close lightning > strike. I was able to successfully repair the LPA replacing both discrete and > SMD components. Performed a Pout calibration using the K3 Utility program > afterward and it passed. > > My 9500 amplifier (driven by the K3) has had a few instances of a high plate > current faults since new in December 2010. These faults had been infrequent > enough to ignore. More recently though the problems have been occurring more > often. Swapping the tube did not help nor did careful inspection inside the > amplifier reveal anything. > > Evidence that the problem is related to the K3 and not the amplifier > presented itself by accident a few days ago. I had the K3’s output set to 40w > and the Alpha was off. I inadvertently bumped the key and noted an > instantaneous output of 54w on the Powermaster II wattmeter. A few more dits, > and the power output settled back to 40w. Hmmm… if the amplifier had been in > line, the K3’s drive set for full legal limit and a first dit resulted in an > additional 30% drive, a high plate current fault might certainly happen. > > This morning I was using the KPA500 amp with my K3’s power set to 28 watts. > After an early AM CW fix I left the station on, walked away and came back in > a few hours hours. On first dit the KPA’s instantaneous power showed 650w on > the Powermaster II and illuminated a red LED on the KPA500, then settled back > down to <500w. > > OK, so it IS the K3 causing the problem BUT the power output spikes occur > very infrequently. It’s difficult to nail down the cause or even the > conditions under which the problem is most likely to occur. > > Reading the archives, others have had power spike issues over the years. Is > there a known fix? I’ve looked briefly at Elecraft’s alerts and mods but > nothing jumps out. > > 73, > John K1JD > Santa Fe, NM > > > > > __ > 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 k2vco@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
