FW: Testing IMD3 (dB) K3S (#10490)
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Subject: Testing IMD3 (dB) K3S (#10490) Hi Can anyone roughly confirm IMD3 K3S ? 10W/100W module recently exchanged under Elecraft swap program Rev A (2019). Testing: Using K3S internal 2 Tone and -60dB power attenuator (50Ohms) , HP 8591E Spectrum Analyzer (Span 10kHz) 72W (Tune, LP100A)out into 50Ohm: IMD3 (#10490) -->about on 160m 34 dB, 80m 32dB, 40m 34 dB, 20m 26dB, 17m 30 dB, 10m 30dB, 6m 26dB Yes, all was aligned (TX Gain test) and showing 100 to 90W full power on all bands. The driving signal to 10W PA (one tone) looked better than 50dBc. I think these IMD3 values are not very impressive. A power amp. would typically further degrade the overall results. So K3S is rather good for CW but not really good as SSB preference? (I have now also a FTDX101MP) Comparing with K3 (#7848) upgraded myself to "S", but still maintaining the old 10/100W modules. 80m and 20m were better by about 6dB!? The two tones (IMD3 Test Tones) however were in both cases never absolutely identical in amplitude (ca. +/-1dB) on the analyzer. Any comments? Tnx, Cu, vy 73 de Andy HB9CVQ, DK2VQ, AK4IG <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: FW: Testing IMD3 (dB) K3S (#10490)
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On 2/7/2020 4:00 PM, [hidden email] wrote:
> I think these IMD3 values are not very impressive. A power amp. would > typically further degrade the overall results. In practice, no, because the K3 and K3S IMD is significantly lower at the power levels needed to drive an amp. My 87As need 45-55W, my KPA1500 30-50W, and KPA500 25-30W, in all cased depending on the band. IMD is also minimized by running the radio near the top of its design range 13.8V nominal, 15V max). > So K3S is rather good for CW but not really good as SSB preference? (I have > now also a FTDX101MP) When they were introduced, the K3 and K3S both pushed the state of the art for CW bandwidth with low phase noise and a carefully shaped keying waveform (that others took years to copy). My measurements of the TX bandwidth of my K3 and several other rigs I was able to borrow are here. http://k9yc.com/P3_Spectrum_Measurements.pdf It's also important to realize that IMD increases CW bandwidth too, because CW is actually 100% square wave amplitude modulation of the carrier. Compare slide #9 with #14 - 16, for example. Those little humps that look like sidebands are IMD, and are heard as clicks. Compare slide #17 (100W SSB) with those that follow. Pink noise is used as a test signal because it's spectrum and dynamics far more closely resemble speech that white noise. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: Testing IMD3 (dB) K3S (#10490)
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In reply to this post by hb9cvq
> [hidden email] wrote:
> > Can anyone roughly confirm IMD3 K3S ? Andy, I'm sorry that your testing showed low TX IMD. Typically all HF bands are in the low 30s (i.e., -30 dBc or better, using the ARRL method, with Vsupply = 14 V). This is similar to that of other transceivers using the same MOSFET PA design. 6 meters is tested at a lower power level per the current specifications (I believe it's 1 dB below 100 W). If yours is worse than the low 30s on one HF band, 20 m in your case, there are a few possibilities. It could be that the 20 meter LPF is not optimized, or that the voltage regulator supplying 5 V to the bias circuitry is off by some amount relative to the normal value. If you sent the radio in at the time of the module swap, our techs should have caught this in final test. If you did the swap yourself, then one of the above issues may apply. Either way, I've asked customer support to contact you, and we'll be happy to cover the cost of any replacement parts on the radio or the modules. 73, Wayne N6KR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: FW: Testing IMD3 (dB) K3S (#10490)
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In reply to this post by hb9cvq
General discussions indicate a higher supply voltage, approaching 14.0
to 14.3 at the radio during transmit, does produce lower IMD products. On the opposite side, lower voltage has been shown to produce higher IMD products. The KPA3A is a Rev E in my radio. The supply voltage as shown on the radio during 100 watts transmit is 13.9 with 14.3 at the supply. I've not measured the IMD. 73 Bob, K4TAX On 2/7/2020 6:00 PM, [hidden email] wrote: > > > > > > Subject: Testing IMD3 (dB) K3S (#10490) > > > > Hi > > > > Can anyone roughly confirm IMD3 K3S ? > > > > 10W/100W module recently exchanged under Elecraft swap program Rev A (2019). > > Testing: Using K3S internal 2 Tone and -60dB power attenuator (50Ohms) , HP > 8591E Spectrum Analyzer (Span 10kHz) > > > > 72W (Tune, LP100A)out into 50Ohm: > > IMD3 (#10490) -->about on 160m 34 dB, 80m 32dB, 40m 34 dB, 20m 26dB, 17m 30 > dB, 10m 30dB, 6m 26dB > > Yes, all was aligned (TX Gain test) and showing 100 to 90W full power on all > bands. > > The driving signal to 10W PA (one tone) looked better than 50dBc. > > > > I think these IMD3 values are not very impressive. A power amp. would > typically further degrade the overall results. > > So K3S is rather good for CW but not really good as SSB preference? (I have > now also a FTDX101MP) > > > > Comparing with K3 (#7848) upgraded myself to "S", but still maintaining the > old 10/100W modules. > > 80m and 20m were better by about 6dB!? > > > > The two tones (IMD3 Test Tones) however were in both cases never absolutely > identical in amplitude (ca. +/-1dB) on the analyzer. > > > > Any comments? > > > > Tnx, Cu, vy 73 de Andy > > HB9CVQ, DK2VQ, AK4IG > > > > <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: FW: Testing IMD3 (dB) K3S (#10490)
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In reply to this post by hb9cvq
I have some comments.
My TX IMD is even worse and I was not very happy with the advice I got from Elecraft. I was advised to use the radio in test mode and use an external amplifier. Periodically I have a complain about it. My 10W PA is also poor even after the FW upgrade that allows additional attenuation to the drive. There are a few of us who discuss this off reflector and it is by no means uncommon. On a more positive note I must say that the transverter port output is exceptionally good. Its really impressive. As for the PA IMD, good luck, you will need it. Regards Conrad PA5Y -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of [hidden email] Sent: 08 February 2020 01:00 To: [hidden email] Subject: [Elecraft] FW: Testing IMD3 (dB) K3S (#10490) Subject: Testing IMD3 (dB) K3S (#10490) Hi Can anyone roughly confirm IMD3 K3S ? 10W/100W module recently exchanged under Elecraft swap program Rev A (2019). Testing: Using K3S internal 2 Tone and -60dB power attenuator (50Ohms) , HP 8591E Spectrum Analyzer (Span 10kHz) 72W (Tune, LP100A)out into 50Ohm: IMD3 (#10490) -->about on 160m 34 dB, 80m 32dB, 40m 34 dB, 20m 26dB, 17m 30 dB, 10m 30dB, 6m 26dB Yes, all was aligned (TX Gain test) and showing 100 to 90W full power on all bands. The driving signal to 10W PA (one tone) looked better than 50dBc. I think these IMD3 values are not very impressive. A power amp. would typically further degrade the overall results. So K3S is rather good for CW but not really good as SSB preference? (I have now also a FTDX101MP) Comparing with K3 (#7848) upgraded myself to "S", but still maintaining the old 10/100W modules. 80m and 20m were better by about 6dB!? The two tones (IMD3 Test Tones) however were in both cases never absolutely identical in amplitude (ca. +/-1dB) on the analyzer. Any comments? Tnx, Cu, vy 73 de Andy HB9CVQ, DK2VQ, AK4IG <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Supply voltage, under load, at the radio?
73, Scott K9MA On 2/8/2020 16:14, Conrad PA5Y wrote: > I have some comments. > > My TX IMD is even worse and I was not very happy with the advice I got from Elecraft. I was advised to use the radio in test mode and use an external amplifier. > > Periodically I have a complain about it. My 10W PA is also poor even after the FW upgrade that allows additional attenuation to the drive. There are a few of us who discuss this off reflector and it is by no means uncommon. > > On a more positive note I must say that the transverter port output is exceptionally good. Its really impressive. > > As for the PA IMD, good luck, you will need it. > > Regards > > Conrad PA5Y > > > > -----Original Message----- > From: [hidden email] <[hidden email]> On Behalf Of [hidden email] > Sent: 08 February 2020 01:00 > To: [hidden email] > Subject: [Elecraft] FW: Testing IMD3 (dB) K3S (#10490) > > > > > > > Subject: Testing IMD3 (dB) K3S (#10490) > > > > Hi > > > > Can anyone roughly confirm IMD3 K3S ? > > > > 10W/100W module recently exchanged under Elecraft swap program Rev A (2019). > > Testing: Using K3S internal 2 Tone and -60dB power attenuator (50Ohms) , HP 8591E Spectrum Analyzer (Span 10kHz) > > > > 72W (Tune, LP100A)out into 50Ohm: > > IMD3 (#10490) -->about on 160m 34 dB, 80m 32dB, 40m 34 dB, 20m 26dB, 17m 30 dB, 10m 30dB, 6m 26dB > > Yes, all was aligned (TX Gain test) and showing 100 to 90W full power on all bands. > > The driving signal to 10W PA (one tone) looked better than 50dBc. > > > > I think these IMD3 values are not very impressive. A power amp. would typically further degrade the overall results. > > So K3S is rather good for CW but not really good as SSB preference? (I have now also a FTDX101MP) > > > > Comparing with K3 (#7848) upgraded myself to "S", but still maintaining the old 10/100W modules. > > 80m and 20m were better by about 6dB!? > > > > The two tones (IMD3 Test Tones) however were in both cases never absolutely identical in amplitude (ca. +/-1dB) on the analyzer. > > > > Any comments? > > > > Tnx, Cu, vy 73 de Andy > > HB9CVQ, DK2VQ, AK4IG > > > > <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ > > > -- Scott K9MA [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Hi from HB9CVQ Andy
My K3S / K3 voltage under load (72W) was 13.1V DC. -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of K9MA Sent: Sonntag, 9. Februar 2020 00:01 To: [hidden email] Subject: Re: [Elecraft] FW: Testing IMD3 (dB) K3S (#10490) Supply voltage, under load, at the radio? 73, Scott K9MA On 2/8/2020 16:14, Conrad PA5Y wrote: > I have some comments. > > My TX IMD is even worse and I was not very happy with the advice I got from Elecraft. I was advised to use the radio in test mode and use an external amplifier. > > Periodically I have a complain about it. My 10W PA is also poor even after the FW upgrade that allows additional attenuation to the drive. There are a few of us who discuss this off reflector and it is by no means uncommon. > > On a more positive note I must say that the transverter port output is exceptionally good. Its really impressive. > > As for the PA IMD, good luck, you will need it. > > Regards > > Conrad PA5Y > > > > -----Original Message----- > From: [hidden email] > <[hidden email]> On Behalf Of [hidden email] > Sent: 08 February 2020 01:00 > To: [hidden email] > Subject: [Elecraft] FW: Testing IMD3 (dB) K3S (#10490) > > > > > > > Subject: Testing IMD3 (dB) K3S (#10490) > > > > Hi > > > > Can anyone roughly confirm IMD3 K3S ? > > > > 10W/100W module recently exchanged under Elecraft swap program Rev A > > Testing: Using K3S internal 2 Tone and -60dB power attenuator (50Ohms) > , HP 8591E Spectrum Analyzer (Span 10kHz) > > > > 72W (Tune, LP100A)out into 50Ohm: > > IMD3 (#10490) -->about on 160m 34 dB, 80m 32dB, 40m 34 dB, 20m 26dB, > 17m 30 dB, 10m 30dB, 6m 26dB > > Yes, all was aligned (TX Gain test) and showing 100 to 90W full power on > > The driving signal to 10W PA (one tone) looked better than 50dBc. > > > > I think these IMD3 values are not very impressive. A power amp. would typically further degrade the overall results. > > So K3S is rather good for CW but not really good as SSB preference? (I > have now also a FTDX101MP) > > > > Comparing with K3 (#7848) upgraded myself to "S", but still maintaining the old 10/100W modules. > > 80m and 20m were better by about 6dB!? > > > > The two tones (IMD3 Test Tones) however were in both cases never absolutely identical in amplitude (ca. +/-1dB) on the analyzer. > > > > Any comments? > > > > Tnx, Cu, vy 73 de Andy > > HB9CVQ, DK2VQ, AK4IG > > > > <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ > > > -- Scott K9MA [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: FW: Testing IMD3 (dB) K3S (#10490)
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On 2020-02-08 7:22 PM, [hidden email] wrote: > > My K3S / K3 voltage under load (72W) was 13.1V DC. 13.1 V is too low for reasonable IMD with *any* 12V "100W" PA. Get the power supply up to 14.0-14.5V. If you can't get at least 14.0 V at full output, do not try to run more than 60W. Note: this is into a *non reactive* 50 Ohm load. If the load differs from 50 +/- j0 Ohms, IMD is likely to be worse due to the mismatched load. 73, ... Joe, W4TV On 2020-02-08 7:22 PM, [hidden email] wrote: > Hi from HB9CVQ Andy > > My K3S / K3 voltage under load (72W) was 13.1V DC. > > > -----Original Message----- > From: [hidden email] <[hidden email]> On > Behalf Of K9MA > Sent: Sonntag, 9. Februar 2020 00:01 > To: [hidden email] > Subject: Re: [Elecraft] FW: Testing IMD3 (dB) K3S (#10490) > > Supply voltage, under load, at the radio? > > 73, > Scott K9MA > > > On 2/8/2020 16:14, Conrad PA5Y wrote: >> I have some comments. >> >> My TX IMD is even worse and I was not very happy with the advice I got > from Elecraft. I was advised to use the radio in test mode and use an > external amplifier. >> >> Periodically I have a complain about it. My 10W PA is also poor even after > the FW upgrade that allows additional attenuation to the drive. There are a > few of us who discuss this off reflector and it is by no means uncommon. >> >> On a more positive note I must say that the transverter port output is > exceptionally good. Its really impressive. >> >> As for the PA IMD, good luck, you will need it. >> >> Regards >> >> Conrad PA5Y >> >> >> >> -----Original Message----- >> From: [hidden email] >> <[hidden email]> On Behalf Of [hidden email] >> Sent: 08 February 2020 01:00 >> To: [hidden email] >> Subject: [Elecraft] FW: Testing IMD3 (dB) K3S (#10490) >> >> >> >> >> >> >> Subject: Testing IMD3 (dB) K3S (#10490) >> >> >> >> Hi >> >> >> >> Can anyone roughly confirm IMD3 K3S ? >> >> >> >> 10W/100W module recently exchanged under Elecraft swap program Rev A > (2019). >> >> Testing: Using K3S internal 2 Tone and -60dB power attenuator (50Ohms) >> , HP 8591E Spectrum Analyzer (Span 10kHz) >> >> >> >> 72W (Tune, LP100A)out into 50Ohm: >> >> IMD3 (#10490) -->about on 160m 34 dB, 80m 32dB, 40m 34 dB, 20m 26dB, >> 17m 30 dB, 10m 30dB, 6m 26dB >> >> Yes, all was aligned (TX Gain test) and showing 100 to 90W full power on > all bands. >> >> The driving signal to 10W PA (one tone) looked better than 50dBc. >> >> >> >> I think these IMD3 values are not very impressive. A power amp. would > typically further degrade the overall results. >> >> So K3S is rather good for CW but not really good as SSB preference? (I >> have now also a FTDX101MP) >> >> >> >> Comparing with K3 (#7848) upgraded myself to "S", but still maintaining > the old 10/100W modules. >> >> 80m and 20m were better by about 6dB!? >> >> >> >> The two tones (IMD3 Test Tones) however were in both cases never > absolutely identical in amplitude (ca. +/-1dB) on the analyzer. >> >> >> >> Any comments? >> >> >> >> Tnx, Cu, vy 73 de Andy >> >> HB9CVQ, DK2VQ, AK4IG >> >> >> >> <https://www.qrz.com/db/HB9CVQ> https://www.qrz.com/db/HB9CVQ >> >> >> > > -- > Scott K9MA > > [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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On 2/8/2020 21:45, Joe Subich, W4TV wrote:
> Note: this is into a *non reactive* 50 Ohm load. If the load > differs from 50 ± j0 Ohms, IMD is likely to be worse due to > the mismatched load. Joe makes a very good point. Even with 14.5 V and a perfect 50 Ohm load, 12 V PA's have marginal IMD at 100 W. If there is a moderate mismatch, like 1.2:1, it can be much worse. Given that ATU's don't consistently get the SWR below that, IMD is often likely to be pretty bad. (It would be very interesting to see some test results with 1.2:1 at various phase angles.) Fortunately, a lot of amplifiers, including all the solid state ones, require much less drive power. Unfortunately, some of the solid state amplifiers are also likely to generate more IMD if they aren't perfectly matched. (And they're not that great when they are matched.) Reducing power a bit should help. Running an amplifier capable of 2.5 kW at 1.5 kW would probably keep the IMD pretty low, even with a moderate mismatch. It would also be very expensive. 73, Scott K9MA -- Scott K9MA [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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