[Elecraft] KPA-1500 power reading?
When I received my KPA-1500, I noticed I had to drive the LEDS into the "red" zone to indicate 1500 Watts into my Bird 43 wattmeter with a 2500W slug, and Palstar DL2K dummy load. There also was a comprehensive part of the KPA-1500 manual that details how to readjust the power indicating LED's, so I was wondering - what gives? The Bird 43 specs have a tolerance of 5% of full scale, which for a 2500 watt slug is 125 watts. I asked Wayne (or was it Eric?) at a show as to what was used by Elecraft to calibrate the amp's power meter and was told they used the LP-100A. So, that is the standard that was used in the Calibration of the KPA-1500's. '73 de JIM N2ZZ -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mark Goldberg Sent: Sunday, February 07, 2021 12:38 PM To: Jim McCook Cc: Elecraft Reflector Subject: Re: [Elecraft] KPA-1500 power reading? The meter itself can be off too. Using more slugs does help things, but to be really sure, test equipment needs to be periodically calibrated, which Hams never do. Dummy loads should be measured with a VNA. So, what you did is a big help, but still can't provide 100% assurance that it is accurate. I understand that is the best most Hams can do and probably better than most. An LP-100A does come with a NIST traceable calibration from the factory and it can be recalibrated, again something Hams never do. I have one fancy scope / spectrum analyzer that I do get calibrated yearly and I use that for a reference. I have a VNA with a set of calibration standards and use that to measure attenuators / taps that I put between my transmitter and the analyzer. I admit I do not calibrate anything else, but I use the calibrated stuff as transfer standards. I also have a couple GPSDOs as frequency standards to compare to. 73, Mark W7MLG On Sat, Feb 6, 2021 at 4:55 PM Jim McCook wrote: > > Good points, Ray and Jim, I should have been more detailed with what I > posted. I checked The Bird 43 with two other Bird 2500w slugs from > friends and they were all reading the same with a dummy load at 1500w. > I did the KPA1500 calibration using the Bird with a high power dummy > load, then checked again with my antennas in band segments where they > present no significant reflected power and near 1:1 SWR. At those > points they were in sync. Most of my antennas are flat on CW segments > at specific spots without using the tuner in the KPA1500. I operate 99% > CW and realize that when the load changes from 50 ohms the Bird reads > wildly high and cannot be trusted. - Jim W6YA > __ > 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 marklgoldb...@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 jboehne...@yahoo.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA-1500 power reading?
The meter itself can be off too. Using more slugs does help things, but to be really sure, test equipment needs to be periodically calibrated, which Hams never do. Dummy loads should be measured with a VNA. So, what you did is a big help, but still can't provide 100% assurance that it is accurate. I understand that is the best most Hams can do and probably better than most. An LP-100A does come with a NIST traceable calibration from the factory and it can be recalibrated, again something Hams never do. I have one fancy scope / spectrum analyzer that I do get calibrated yearly and I use that for a reference. I have a VNA with a set of calibration standards and use that to measure attenuators / taps that I put between my transmitter and the analyzer. I admit I do not calibrate anything else, but I use the calibrated stuff as transfer standards. I also have a couple GPSDOs as frequency standards to compare to. 73, Mark W7MLG On Sat, Feb 6, 2021 at 4:55 PM Jim McCook wrote: > > Good points, Ray and Jim, I should have been more detailed with what I > posted. I checked The Bird 43 with two other Bird 2500w slugs from > friends and they were all reading the same with a dummy load at 1500w. > I did the KPA1500 calibration using the Bird with a high power dummy > load, then checked again with my antennas in band segments where they > present no significant reflected power and near 1:1 SWR. At those > points they were in sync. Most of my antennas are flat on CW segments > at specific spots without using the tuner in the KPA1500. I operate 99% > CW and realize that when the load changes from 50 ohms the Bird reads > wildly high and cannot be trusted. - Jim W6YA > __ > 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 marklgoldb...@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] KPA-1500 power reading?
Good points, Ray and Jim, I should have been more detailed with what I posted. I checked The Bird 43 with two other Bird 2500w slugs from friends and they were all reading the same with a dummy load at 1500w. I did the KPA1500 calibration using the Bird with a high power dummy load, then checked again with my antennas in band segments where they present no significant reflected power and near 1:1 SWR. At those points they were in sync. Most of my antennas are flat on CW segments at specific spots without using the tuner in the KPA1500. I operate 99% CW and realize that when the load changes from 50 ohms the Bird reads wildly high and cannot be trusted. - Jim W6YA __ 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] KPA-1500 power reading?
On 2/6/2021 12:05 PM, Ray wrote: Trust the Wattmeter Only if it is seeing a 50 Ohm Dummy Load. Bird slugs have a tolerance of 5% of full scale, and the reading is only valid into a 50 ohm resistive load. The LP100A is 5% of the reading at any power level and into complex loads (i.e, not only 50 ohms resistive). Years ago, Electraft used an LP100A for final test of their rigs. Don't know if they still do. About five years ago, I bought W6OSP's LP100A from his estate and added a second coupler for my SO2R station, and had both calibrated at his factory. It auto-switches with signal from the amplifiers for the two radios. 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] KPA-1500 power reading?
Trust the Wattmeter Only if it is seeing a 50 Ohm Dummy Load. WA6VAB Ray From: Jim McCook Sent: Saturday, February 6, 2021 11:35 AM To: Elecraft Reflector Subject: Re: [Elecraft] KPA-1500 power reading? I trust my Bird 43 wattmeter that's in line with the amplifier output, so I recalibrated the KPA-1500 wattmeter reading per band to correlate more closely with it. See WMTR ADJUST in the KPA-1500 menu. Jim W6YA __ 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 wa6...@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] KPA-1500 power reading?
I trust my Bird 43 wattmeter that's in line with the amplifier output, so I recalibrated the KPA-1500 wattmeter reading per band to correlate more closely with it. See WMTR ADJUST in the KPA-1500 menu. Jim W6YA __ 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] KPA-1500 power reading ?
I see something similar with my (non-Elecraft) amp. The amp's display matches a Bird 43 I had connected with a 12 inch cable from the amp and then goes into an accurate 50 Ohm dummy load. I usually do not leave the Bird in-line, but had this set up for testing the amp when I first got it. The remote LP100 sensor I have is actually on a cable that is about 3 feet from the amp and it usually reads HIGHER than the amp does, even into the same dummy load. Ron WA2EIO On 2/5/2021 10:48 PM, Bill Johnson wrote: I accept differences do to cable lengths and different points of monitoring. No two will ever be the same when sampling rf at different points. Unless all connections and cables are perfectly perfect "-) Bill K9YEQ -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Ed Stallman Sent: Friday, February 5, 2021 12:23 PM To: Elecraft@mailman.qth.net Subject: [Elecraft] KPA-1500 power reading ? The KPA1500 is new to me and very happy with my purchase . I'm using the LP-100A watt meter and comparing it with the KPA-1500 they both read close enough 10 to 160 . On 6m I'm seeing a bigger spread with the LP-100A reading 1500w the KPA-1500 is showing 1375w . If you look at this in DB , it's nothing. I know the LP-100A is very accurate and the only way to know for sure is to have Larry at Telepost test it. Most likely wont do wont do that. Are their others that see a difference on 6m ? Thanks Ed N5DG __ 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 k9...@live.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 wa2...@optonline.net __ 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] KPA-1500 power reading ?
I accept differences do to cable lengths and different points of monitoring. No two will ever be the same when sampling rf at different points. Unless all connections and cables are perfectly perfect "-) Bill K9YEQ -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Ed Stallman Sent: Friday, February 5, 2021 12:23 PM To: Elecraft@mailman.qth.net Subject: [Elecraft] KPA-1500 power reading ? The KPA1500 is new to me and very happy with my purchase . I'm using the LP-100A watt meter and comparing it with the KPA-1500 they both read close enough 10 to 160 . On 6m I'm seeing a bigger spread with the LP-100A reading 1500w the KPA-1500 is showing 1375w . If you look at this in DB , it's nothing. I know the LP-100A is very accurate and the only way to know for sure is to have Larry at Telepost test it. Most likely wont do wont do that. Are their others that see a difference on 6m ? Thanks Ed N5DG __ 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 k9...@live.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] KPA-1500 power reading ?
Jim, using 4ft of low loss Davis RF Bury Flex between LPA and KPA , 6m is the one band with the biggest difference , KPA1500 reading 125 to 150 watts less . I've decided with the LP-100A in better line of site , I'm going with it . Ed N5DG On 2/5/2021 6:52 PM, Jim Brown wrote: On 2/5/2021 10:22 AM, Ed Stallman wrote: I'm using the LP-100A watt meter and comparing it with the KPA-1500 they both read close enough 10 to 160 . On 6m I'm seeing a bigger spread with the LP-100A reading 1500w the KPA-1500 is showing 1375w . I also have an LP100A inline between my amp and my antenna switching. What coax is between the amp and the LP100A, and how long is it? The loss in this cable increases with frequency. Also, I believe that the KPA1500 reads power on the amplifier side of the tuner, and it's not lossless. I nearly always see a fractional dB between them. 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 ed.n...@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] KPA-1500 power reading ?
On 2/5/2021 10:22 AM, Ed Stallman wrote: I'm using the LP-100A watt meter and comparing it with the KPA-1500 they both read close enough 10 to 160 . On 6m I'm seeing a bigger spread with the LP-100A reading 1500w the KPA-1500 is showing 1375w . I also have an LP100A inline between my amp and my antenna switching. What coax is between the amp and the LP100A, and how long is it? The loss in this cable increases with frequency. Also, I believe that the KPA1500 reads power on the amplifier side of the tuner, and it's not lossless. I nearly always see a fractional dB between them. 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] KPA-1500 power reading ?
Lou , just checked again on the HF bands 80m LPA=1495 and KPA=1501 40m LPA=1476 and KPA=1421 6m LPA=1512 and KPA=1325 This is not concerning to me at all . My curiosity and a cold rainy told me to see how others compared . I suspect this is the case with any two watt meters . I know it's adjustable in the KPA 1500 but I'll not bother . Thanks everyone for ur reply . 73 Ed N5DG On 2/5/2021 5:06 PM, Lou W0FK wrote: Ed Stallman-2 wrote The KPA1500 is new to me and very happy with my purchase . I'm using the LP-100A watt meter and comparing it with the KPA-1500 they both read close enough 10 to 160 . On 6m I'm seeing a bigger spread with the LP-100A reading 1500w the KPA-1500 is showing 1375w . If you look at this in DB , it's nothing. I know the LP-100A is very accurate and the only way to know for sure is to have Larry at Telepost test it. Most likely wont do wont do that. Are their others that see a difference on 6m ? Thanks Ed N5DG I have the same setup Ed (KPA1500/LPA-100A). I've always seen a difference, and never really paid much attention to it. When I read your email I ran some very quick and dirty tests, here's what I'm seeing: 80M: LPA -- 1322, KPA1500 -- 1513 40M: LPA -- 1325, KPA1500 -- 1504 6M: LPA -- 1345, KPA1500 -- 1550 Pretty consistent with your 6M readings. Are you seeing much closer numbers than mine? 73, Lou W0FK -- Sent from: http://elecraft.365791.n2.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 ed.n...@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] KPA-1500 power reading ?
Ed Stallman-2 wrote > The KPA1500 is new to me and very happy with my purchase . I'm using the > LP-100A watt meter and comparing it with the KPA-1500 they both read > close enough 10 to 160 . On 6m I'm seeing a bigger spread with the > LP-100A reading 1500w the KPA-1500 is showing 1375w . If you look at > this in DB , it's nothing. I know the LP-100A is very accurate and the > only way to know for sure is to have Larry at Telepost test it. Most > likely wont do wont do that. Are their others that see a difference on 6m > ? > > Thanks Ed N5DG I have the same setup Ed (KPA1500/LPA-100A). I've always seen a difference, and never really paid much attention to it. When I read your email I ran some very quick and dirty tests, here's what I'm seeing: 80M: LPA -- 1322, KPA1500 -- 1513 40M: LPA -- 1325, KPA1500 -- 1504 6M: LPA -- 1345, KPA1500 -- 1550 Pretty consistent with your 6M readings. Are you seeing much closer numbers than mine? 73, Lou W0FK -- Sent from: http://elecraft.365791.n2.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
[Elecraft] KPA-1500 power reading ?
The KPA1500 is new to me and very happy with my purchase . I'm using the LP-100A watt meter and comparing it with the KPA-1500 they both read close enough 10 to 160 . On 6m I'm seeing a bigger spread with the LP-100A reading 1500w the KPA-1500 is showing 1375w . If you look at this in DB , it's nothing. I know the LP-100A is very accurate and the only way to know for sure is to have Larry at Telepost test it. Most likely wont do wont do that. Are their others that see a difference on 6m ? Thanks Ed N5DG __ 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
