K4 pre-distortion?
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I’ve not seen confirmation as to whether the K4 uses pre-distortion to
improve the TX IMD levels. The inclusion of a sample input socket suggests it does. If so, does a barefoot K4 use pre-distortion and will there be a mod kit for the KPA500 to provide a sample output? 73 Dave -- Sent from my iPhone SE ______________________________________________________________ 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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Would having if be a deal breaker?
Mike Sent from my iPad > On Jun 15, 2019, at 6:59 AM, Dave <[hidden email]> wrote: > > I’ve not seen confirmation as to whether the K4 uses pre-distortion to > improve the TX IMD levels. The inclusion of a sample input socket suggests > it does. If so, does a barefoot K4 use pre-distortion and will there be a > mod kit for the KPA500 to provide a sample output? > > 73 Dave > -- > Sent from my iPhone SE > ______________________________________________________________ > 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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In a word “yes”. Given that in order to match the RX performance of my
existing K3/P3 (dual RX, K3S synths) it would require me to purchase the most expensive K4 version, then to me the only possible advantages over my K3 would be improved SSB TX IMD and improved RX DSP noise reduction. The K3 noise reduction is very poor, I have never found it useful on SSB, and certainly not on CW. The K3 TX SSB 3rd/5th/7th/9th IMD products spread very wide and resemble a felled Christmas tree laid on its side. So a significant improvement in these areas is where the K4 needs to start. Reading between the lines on both the Elecraft FAQs and this list, from the lack of an official mention of pre-distortion or improved TX IMD, I take it to mean the provision is a possible future upgrade and not included initially. Kinda like Icom including a frequency reference input socket on the IC9700 and buyers (incorrectly) assuming the IC9700 locks to an external reference (which it doesn’t). 73 Dave >On Sat, 15 Jun 2019 at 12:31, Michael >Walker wrote: > >Would having if be a deal breaker? > > > >Mike > > > >Sent from my iPad > > > -- Sent from my iPhone SE ______________________________________________________________ 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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-----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Dave Sent: Sunday, June 16, 2019 8:40 AM To: [hidden email] Subject: Re: [Elecraft] K4 pre-distortion? In a word yes. Given that in order to match the RX performance of my existing K3/P3 (dual RX, K3S synths) it would require me to purchase the most expensive K4 version, then to me the only possible advantages over my K3 would be improved SSB TX IMD and improved RX DSP noise reduction. ---------------------------Any numbers out about TX IMD of the K4? The K3 noise reduction is very poor, I have never found it useful on SSB, and certainly not on CW. The K3 TX SSB 3rd/5th/7th/9th IMD products spread very wide and resemble a felled Christmas tree laid on its side. So a significant improvement in these areas is where the K4 needs to start. ---------------------------True - there are much better noise reduction algorithms around these days. The noiseblanker in the K3/K3S needs some revision too! TX IMD in the K3S (can´t speak of the K3) can be improved somewhat by increasing the bias however what is possible with a pair of RD100HHF final transistors @ 13,8 VDC is clearly demonstrated by the TS-590 and the new TS-890 by Kenwood (I am not a Kenwood promoter or fan but a clean signal promoter!). Even with increased bias the K3S is not as good............................ Reading between the lines on both the Elecraft FAQs and this list, from the lack of an official mention of pre-distortion or improved TX IMD, I take it to mean the provision is a possible future upgrade and not included initially. Kinda like Icom including a frequency reference input socket on the IC9700 and buyers (incorrectly) assuming the IC9700 locks to an external reference (which it doesnt). --------------------------Amplifier manufacturers and radio manufacturers alike seem to have accepted that predistortion is the future however only ONE manufacturer so far has implemented it as soon as the algorithm became available for Ham Radio. Other than that it is easy and inexpensive to add an additional sampler in the output of an amplifier and/or an extra jack on a radio and label it RF SAMPLE OUTPUT/INPUT. For the moment it is more marketing than technical necessity 73 Roger, DL5RBW 73 Dave >On Sat, 15 Jun 2019 at 12:31, Michael >Walker wrote: > >Would having if be a deal breaker? > > > >Mike > > > >Sent from my iPad > > > -- Sent from my iPhone SE ______________________________________________________________ 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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In reply to this post by Dave Johnson
I don't think any automatic noise reduction system is intended for use
on Morse code. The way to reduce noise on that is to use a narrow filter. NR is really only intended for speech (or in the wider world, music). The key characteristic is that only a small part of the spectrum is important at any one time, but that part is continually changing. NR systems try to work out which parts of the audio spectrum are important and which are not, and construct filters to remove the latter. For CW anything other than the immediate area around the signal is unimportant, and it is not continually changing. The only way you could do better with Morse is by recognizing the signal and regenerating it as a pure keyed tone. The human brain and ear are actually rather good at noise reduction; the problem is that they tire easily. NR attempts to make listening less tiring, not to change a signal from unreadable to readable. -- David Woolley On 16/06/2019 07:39, Dave wrote: > The K3 noise reduction is very poor, I have never found it useful on SSB, > and certainly not on CW. ______________________________________________________________ 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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