Re: [Elecraft] K4HD question
On 5/29/2019 22:12, Jim Brown wrote: BEFORE the days of microprocessors, switch-mode power supplies, and other power control systems that use square waves, nearly all man-made noise was impulse noise. NOW, most of the noise that surrounds us is from those microprocessors, switch-mode supplies, and other power control equipment. That noise is NOT impulse noise, and noise blankers cannot act on it. Alas, even in my urban neighborhood, I fear the day is coming when all this electronics generated noise will drown out the line noise. -- Scott K9MA k...@sdellington.us __ 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
Re: [Elecraft] K4HD question
On 5/29/2019 6:57 PM, Fred Jensen wrote: Noise blankers were designed for repetitive impulse noise, the largest former example of which was ignition noise from vehicles. They have not ever been very effective against power line hash which tends to be non-impulsive and highly random. Huh? The ARRL book on power line noise specifically states that virtually all power line noise is impulse noise, the result of arcing at positive and negative peaks of the 60 Hz line voltage. It is NOT random noise. It IS quite broadband. Arcing can also occur in big motors, or in any system where an arc occurs. BEFORE the days of microprocessors, switch-mode power supplies, and other power control systems that use square waves, nearly all man-made noise was impulse noise. NOW, most of the noise that surrounds us is from those microprocessors, switch-mode supplies, and other power control equipment. That noise is NOT impulse noise, and noise blankers cannot act on it. 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
Re: [Elecraft] K4HD question
On 5/29/2019 20:57, Fred Jensen wrote: Noise blankers were designed for repetitive impulse noise, the largest former example of which was ignition noise from vehicles. They have not ever been very effective against power line hash which tends to be non-impulsive and highly random. That has not been my experience. Most line noise IS impulsive, and some noise blankers can be quite effective, but only if there are no strong signals nearby. I'm hoping a direct sampling receiver could avoid that problem. One method that has been used in the (distant) past was a second receiver tuned to a nearby but clear frequency to control the noise blanker. It seems that a direct sampling receiver ought to be able to do something like that. 73, Scott K9MA -- Scott K9MA k...@sdellington.us __ 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
Re: [Elecraft] K4HD question
Noise blankers were designed for repetitive impulse noise, the largest former example of which was ignition noise from vehicles. They have not ever been very effective against power line hash which tends to be non-impulsive and highly random. These days, repetitive ignition noise is not a problem for many, don't know why, there are still spark plugs in there. Power line hash comes from a myriad of sources ... hardware anchoring insulators, transformers, fuses, and the like, as well as micro arcing across dust covered insulators. It's highly random, over even small time intervals, and just not the enemy noise blankers were designed to fight. If Wayne had graduated from Hogwarts, he might have some magic to make them work on power line hash. Lacking that, not sure. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 5/29/2019 6:43 PM, K9MA wrote: I've never found the K3 noise blanker to be very effective on power line noise, and I've tried all possible combinations of settings. If the K4 noise blanker were really effective on line noise, I might buy one. 73, Scott K9MA On 5/29/2019 20:39, Wayne Burdick wrote: There are some subtleties in noise blanking that may distinguish the two modes (direct sampling or superhet). The blanking used in direct-sampling should have an advantage on complex, high-duty-cycle noise sources, while the hardware blanking modules used in the superhet may have an advantage with extremely short pulse sources. We'll be extensively testing and comparing them. __ 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
Re: [Elecraft] K4HD question
I've never found the K3 noise blanker to be very effective on power line noise, and I've tried all possible combinations of settings. If the K4 noise blanker were really effective on line noise, I might buy one. 73, Scott K9MA On 5/29/2019 20:39, Wayne Burdick wrote: There are some subtleties in noise blanking that may distinguish the two modes (direct sampling or superhet). The blanking used in direct-sampling should have an advantage on complex, high-duty-cycle noise sources, while the hardware blanking modules used in the superhet may have an advantage with extremely short pulse sources. We'll be extensively testing and comparing them. -- Scott K9MA k...@sdellington.us __ 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
Re: [Elecraft] K4HD question
> Gary Smith wrote: > > At this time there are no nearby hams to > disrupt my K3s. There are no local AM > broadcasters that come in as overload. I > do have issues with a few 2nd harmonic > stations from the BC band, one for example > from S. America on 1.8400. I won't likely > be using my K4 at a contest site and I am > the only ham in the house. > > With that, is there anything the K4HD > offers me Rx-wise, or otherwise, that the > K4D does not? There are some subtleties in noise blanking that may distinguish the two modes (direct sampling or superhet). The blanking used in direct-sampling should have an advantage on complex, high-duty-cycle noise sources, while the hardware blanking modules used in the superhet may have an advantage with extremely short pulse sources. We'll be extensively testing and comparing them. 73, Wayne N6KR __ 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
Re: [Elecraft] K4HD question
Thanks for the reply, As I require diversity , the K4D is necessary, as I also require an autotuner, I need that as well. The costs are adding up. I certainly don't want a new rig that has in any way, less capability than the fully loaded K3s I have now. If a K4HD with autotuner is functionally excess to my having a K4D with autotuner, that helps me budget. 73, Gary KA1J > Any of these things you mentioned might not bother you now BECAUSE > you are using a K3. > > The K4D adds a second A/D chain with dedicated front end filters for > whatever band the second receiver is tuned to. Plus diversity > reception. > > I seem to recall some reference to a "wide-band" mode, which may > come in to play if the two receivers in the K4 are tuned to widely > disparate frequencies (e.g., one on 80M, one on 20M). This could > exacerbate the A/D overload issue with wide-band direct sampled SDRs. > Wouldn´t be an issue with the K4D. Although you might need a K4HD > to get to the heat-proof front end you currently have with the K3. > > Grant NQ5T > K3 #2091 KX3 #8342 > > > On May 29, 2019, at 3:52 PM, Gary Smith wrote: > > > > At this time there are no nearby hams to > > disrupt my K3s. There are no local AM > > broadcasters that come in as overload. I > > do have issues with a few 2nd harmonic > > stations from the BC band, one for example > > from S. America on 1.8400. I won't likely > > be using my K4 at a contest site and I am > > the only ham in the house. > > > > With that, is there anything the K4HD > > offers me Rx-wise, or otherwise, that the > > K4D does not? > > > > __ 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
Re: [Elecraft] K4HD question
Any of these things you mentioned might not bother you now BECAUSE you are using a K3. The K4D adds a second A/D chain with dedicated front end filters for whatever band the second receiver is tuned to. Plus diversity reception. I seem to recall some reference to a “wide-band” mode, which may come in to play if the two receivers in the K4 are tuned to widely disparate frequencies (e.g., one on 80M, one on 20M). This could exacerbate the A/D overload issue with wide-band direct sampled SDRs. Wouldn’t be an issue with the K4D. Although you might need a K4HD to get to the heat-proof front end you currently have with the K3. Grant NQ5T K3 #2091 KX3 #8342 > On May 29, 2019, at 3:52 PM, Gary Smith wrote: > > At this time there are no nearby hams to > disrupt my K3s. There are no local AM > broadcasters that come in as overload. I > do have issues with a few 2nd harmonic > stations from the BC band, one for example > from S. America on 1.8400. I won't likely > be using my K4 at a contest site and I am > the only ham in the house. > > With that, is there anything the K4HD > offers me Rx-wise, or otherwise, that the > K4D does not? > __ 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
