Amplitude variation on K3S with JT65B
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Amplitude variation on K3S with JT65B
 
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Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft support I thought that I would ask the group about a problem that I have with my K3S.
When I run JT65B and even to a lesser extent FT8 I see unacceptable amplitude variation on both the 6m output and the transverter output (on 28MHz). If I put my E4406 Spectrum analyser on peak hold with a narrow span and 10Hz RBW I see amplitude variations of a little over 1dB on the modulation tones across the passband. To save time. 1. On the ALC meter I have 4 bars lit up with the 5th occasionally flickering - the audio drive level is correct; it is not an ALC issue 2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and 100W on 6m. 3. I am using DATA A so no TX EQ or compression 4. The audio has from WSJT-X been measured on a UPV audio analyser and there is less than 0.1dB variation when using a UMC404HD sound card 5. The effect is observed with both Line input drive and the UMC404HD soundcard and the internal K3S codec 6. My old TS2000X does not exhibit more than 0.1dB amplitude variation with the same sound card providing audio and the same test setup 7. I have verified the amplitude variations at RF with a diode detector and an oscilloscope 8. The effect is clearly visible on several power meters 9. This AM causes some spectral re-growth, although this is tolerable So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I was considering buying an Inrad #718 filter. This is very critical for EME when signals are weak at the RX side, if you have amplitude variations and you are at the threshold of detection at the receiving station this can cause decodes to fail. This is more important on 6m EME than 2m where I have more margin. I think that this will be quite common, has anybody else got a K3S and the equipment to check and verify my observations? 73 Conrad PA5Y ______________________________________________________________ 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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Conrad,
My friend just had the issue you described with a different brand radio. He was transmitting near the high end of the TX filter and on higher tones of the FT8 the power would drop causing the TX power to waiver. The fix for him was to enable Fake It in the WSJT-X radio settings tab. That keeps the TX audio centered between 1 kHz and 2 kHz. Well within the TX filter bandwidth. Dave wo2x Sent from my waxed string and tin cans. > On Oct 21, 2020, at 7:51 AM, Conrad PA5Y <[hidden email]> wrote: > > Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft support I thought that I would ask the group about a problem that I have with my K3S. > > When I run JT65B and even to a lesser extent FT8 I see unacceptable amplitude variation on both the 6m output and the transverter output (on 28MHz). If I put my E4406 Spectrum analyser on peak hold with a narrow span and 10Hz RBW I see amplitude variations of a little over 1dB on the modulation tones across the passband. > > To save time. > > > 1. On the ALC meter I have 4 bars lit up with the 5th occasionally flickering - the audio drive level is correct; it is not an ALC issue > 2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and 100W on 6m. > 3. I am using DATA A so no TX EQ or compression > 4. The audio has from WSJT-X been measured on a UPV audio analyser and there is less than 0.1dB variation when using a UMC404HD sound card > 5. The effect is observed with both Line input drive and the UMC404HD soundcard and the internal K3S codec > 6. My old TS2000X does not exhibit more than 0.1dB amplitude variation with the same sound card providing audio and the same test setup > 7. I have verified the amplitude variations at RF with a diode detector and an oscilloscope > 8. The effect is clearly visible on several power meters > 9. This AM causes some spectral re-growth, although this is tolerable > > So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I was considering buying an Inrad #718 filter. > > This is very critical for EME when signals are weak at the RX side, if you have amplitude variations and you are at the threshold of detection at the receiving station this can cause decodes to fail. This is more important on 6m EME than 2m where I have more margin. > > I think that this will be quite common, has anybody else got a K3S and the equipment to check and verify my observations? > > 73 > > Conrad PA5Y > ______________________________________________________________ > 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: Amplitude variation on K3S with JT65B
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In reply to this post by Conrad PA5Y
I have a K3 and a K3S at my Caribbean station... I see the same behavior on
my K3S but not on the K3. I've calibrated it several times but have not diagnosed it past that. I've seen the power vary by as much as 50% at times. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch K9ZC Staunton, Illinois Owner Operator Villa Grand Piton J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook! Moderator North American QRO Group at Groups.IO. email: [hidden email] -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of Conrad PA5Y Sent: Wednesday, October 21, 2020 6:50 AM To: [hidden email] Subject: [Elecraft] Amplitude variation on K3S with JT65B Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft support I thought that I would ask the group about a problem that I have with my K3S. When I run JT65B and even to a lesser extent FT8 I see unacceptable amplitude variation on both the 6m output and the transverter output (on 28MHz). If I put my E4406 Spectrum analyser on peak hold with a narrow span and 10Hz RBW I see amplitude variations of a little over 1dB on the modulation tones across the passband. To save time. 1. On the ALC meter I have 4 bars lit up with the 5th occasionally flickering - the audio drive level is correct; it is not an ALC issue 2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and 100W on 6m. 3. I am using DATA A so no TX EQ or compression 4. The audio has from WSJT-X been measured on a UPV audio analyser and there is less than 0.1dB variation when using a UMC404HD sound card 5. The effect is observed with both Line input drive and the UMC404HD soundcard and the internal K3S codec 6. My old TS2000X does not exhibit more than 0.1dB amplitude variation with the same sound card providing audio and the same test setup 7. I have verified the amplitude variations at RF with a diode detector and an oscilloscope 8. The effect is clearly visible on several power meters 9. This AM causes some spectral re-growth, although this is tolerable So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I was considering buying an Inrad #718 filter. This is very critical for EME when signals are weak at the RX side, if you have amplitude variations and you are at the threshold of detection at the receiving station this can cause decodes to fail. This is more important on 6m EME than 2m where I have more margin. I think that this will be quite common, has anybody else got a K3S and the equipment to check and verify my observations? 73 Conrad PA5Y ______________________________________________________________ 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] -- This email has been checked for viruses by AVG. https://www.avg.com ______________________________________________________________ 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: Amplitude variation on K3S with JT65B
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My K3 doing the same variation. Now I am running my K3, at 70% bellow
100 watts so it will not push above the limit like I did with my KPA500. My KPA500 is back at the Elecraft hospital. KE1F On 10/21/2020 10:48 AM, Dr. William J. Schmidt wrote: > I have a K3 and a K3S at my Caribbean station... I see the same behavior on > my K3S but not on the K3. I've calibrated it several times but have not > diagnosed it past that. I've seen the power vary by as much as 50% at > times. > > > Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ > > Owner - Operator > Big Signal Ranch – K9ZC > Staunton, Illinois > > Owner – Operator > Villa Grand Piton – J68HZ > Soufriere, St. Lucia W.I. > Rent it: www.VillaGrandPiton.com > Like us on Facebook! > > Moderator – North American QRO Group at Groups.IO. > > email: [hidden email] > > > -----Original Message----- > From: [hidden email] <[hidden email]> On > Behalf Of Conrad PA5Y > Sent: Wednesday, October 21, 2020 6:50 AM > To: [hidden email] > Subject: [Elecraft] Amplitude variation on K3S with JT65B > > Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft > support I thought that I would ask the group about a problem that I have > with my K3S. > > When I run JT65B and even to a lesser extent FT8 I see unacceptable > amplitude variation on both the 6m output and the transverter output (on > 28MHz). If I put my E4406 Spectrum analyser on peak hold with a narrow span > and 10Hz RBW I see amplitude variations of a little over 1dB on the > modulation tones across the passband. > > To save time. > > > 1. On the ALC meter I have 4 bars lit up with the 5th occasionally > flickering - the audio drive level is correct; it is not an ALC issue > 2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and > 100W on 6m. > 3. I am using DATA A so no TX EQ or compression > 4. The audio has from WSJT-X been measured on a UPV audio analyser and > there is less than 0.1dB variation when using a UMC404HD sound card > 5. The effect is observed with both Line input drive and the UMC404HD > soundcard and the internal K3S codec > 6. My old TS2000X does not exhibit more than 0.1dB amplitude variation > with the same sound card providing audio and the same test setup > 7. I have verified the amplitude variations at RF with a diode detector > and an oscilloscope > 8. The effect is clearly visible on several power meters > 9. This AM causes some spectral re-growth, although this is tolerable > > So given all that I am beginning to wonder if the problem is due to filter > ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I > was considering buying an Inrad #718 filter. > > This is very critical for EME when signals are weak at the RX side, if you > have amplitude variations and you are at the threshold of detection at the > receiving station this can cause decodes to fail. This is more important on > 6m EME than 2m where I have more margin. > > I think that this will be quite common, has anybody else got a K3S and the > equipment to check and verify my observations? > > 73 > > Conrad PA5Y > ______________________________________________________________ > 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: Amplitude variation on K3S with JT65B
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In reply to this post by Conrad PA5Y
On 10/21/2020 4:49 AM, Conrad PA5Y wrote:
> So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? Many years ago, when I replaced stock 2.7kHz filters with 2.8 kHz filters in both my rigs, it significantly reduced the incidental AM I was seeing on RTTY. 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: Amplitude variation on K3S with JT65B
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In reply to this post by Dave wo2x
Fake It keeps the tones between 1500-2000 Hz. (not 1000) so that the
harmonic energy is out of the passband. Also the response of the sound card has some variation at different pitches (it's not a totally flat response), so try different tones. 73, Rick NK7I On 10/21/2020 6:19 AM, Dave wrote: > Conrad, > > My friend just had the issue you described with a different brand radio. He was transmitting near the high end of the TX filter and on higher tones of the FT8 the power would drop causing the TX power to waiver. > > The fix for him was to enable Fake It in the WSJT-X radio settings tab. That keeps the TX audio centered between 1 kHz and 2 kHz. Well within the TX filter bandwidth. > > Dave wo2x > > Sent from my waxed string and tin cans. > >> On Oct 21, 2020, at 7:51 AM, Conrad PA5Y <[hidden email]> wrote: >> >> Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft support I thought that I would ask the group about a problem that I have with my K3S. >> >> When I run JT65B and even to a lesser extent FT8 I see unacceptable amplitude variation on both the 6m output and the transverter output (on 28MHz). If I put my E4406 Spectrum analyser on peak hold with a narrow span and 10Hz RBW I see amplitude variations of a little over 1dB on the modulation tones across the passband. >> >> To save time. >> >> >> 1. On the ALC meter I have 4 bars lit up with the 5th occasionally flickering - the audio drive level is correct; it is not an ALC issue >> 2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and 100W on 6m. >> 3. I am using DATA A so no TX EQ or compression >> 4. The audio has from WSJT-X been measured on a UPV audio analyser and there is less than 0.1dB variation when using a UMC404HD sound card >> 5. The effect is observed with both Line input drive and the UMC404HD soundcard and the internal K3S codec >> 6. My old TS2000X does not exhibit more than 0.1dB amplitude variation with the same sound card providing audio and the same test setup >> 7. I have verified the amplitude variations at RF with a diode detector and an oscilloscope >> 8. The effect is clearly visible on several power meters >> 9. This AM causes some spectral re-growth, although this is tolerable >> >> So given all that I am beginning to wonder if the problem is due to filter ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I was considering buying an Inrad #718 filter. >> >> This is very critical for EME when signals are weak at the RX side, if you have amplitude variations and you are at the threshold of detection at the receiving station this can cause decodes to fail. This is more important on 6m EME than 2m where I have more margin. >> >> I think that this will be quite common, has anybody else got a K3S and the equipment to check and verify my observations? >> >> 73 >> >> Conrad PA5Y >> ______________________________________________________________ >> 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] 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: Amplitude variation on K3S with JT65B
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On 10/21/2020 10:56 AM, Rick NK7I wrote:
> Also the response of the sound card has some variation at different > pitches (it's not a totally flat response), so try different tones. If it does, it's broke, or a piece of crap. 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: Amplitude variation on K3S with JT65B
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I wish people would actually read emails.....
I stated: 4. The audio from WSJT-X been measured on a UPV audio analyser and there is less than 0.1dB variation when using a UMC404HD sound card. I even numbered the relevant stuff to make it easy to read. A UPV audio analyser is quite good at it's job and something of an industry standard in EU broadcast measurements. It seems that the stock 2.7kHz filter is the culprit. Confirmed privately by 2 EME operators and by Jim K9YC. So I will buy a couple of Inrad 2.8kHz filters. 73 Conrad PA5Y -----Original Message----- From: [hidden email] <[hidden email]> On Behalf Of Jim Brown Sent: 21 October 2020 20:49 To: [hidden email] Subject: Re: [Elecraft] Amplitude variation on K3S with JT65B On 10/21/2020 10:56 AM, Rick NK7I wrote: > Also the response of the sound card has some variation at different > pitches (it's not a totally flat response), so try different tones. If it does, it's broke, or a piece of crap. 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] ______________________________________________________________ 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: Amplitude variation on K3S with JT65B
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On 10/22/2020 9:24 AM, Conrad PA5Y wrote:
> So I will buy a couple of Inrad 2.8kHz filters. Note that while Elecraft filters have been sourced from Inrad, Elecraft has an additional spec for IMD that may not be true of those purchased direct from Inrad. 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: Amplitude variation on K3S with JT65B
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In reply to this post by Conrad PA5Y
Conrad and all:
Another reason I am glad that I chose the 2.8 KHz and 400 Hz filters when I purchased my K3 in 2010. I do not use the 2nd IF when I run 2m-eme (JT65B under MAP65). In fact I have FL3 open (no filter) and select it in diversity mode to reduce zero frequency "suck out" on the MAP65 spectrum screen. I tap off the 1st IF from both main and subRx to feed dual SDR's before the filters. But running either WSJT-10 or WSJT-X I do use line out audio with 2.8 KHz filter selected in DATA Mode. I run this on 6m and 23cm eme. ------------------------------------ It seems that the stock 2.7kHz filter is the culprit. Confirmed privately by 2 EME operators and by Jim K9YC. So I will buy a couple of Inrad 2.8kHz filters. 73 Conrad PA5Y 73, Ed - KL7UW http://www.kl7uw.com Dubus-NA Business mail: [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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