KNB2 vs. electric fence.
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Hey folks,
I've recently started picking up relatively strong pulses at 1 second intervals on my K2. I suspect they're coming from a new electric fence somewhere in the neighborhood. But where they're coming from is immaterial to my question. Should the KNB2 noise blanker be effective against this type of noise? I've always thought that such impulse type noise was exactly what noise blankers were supposed to work best on, but I hear no difference in the pulses whether the NB is on or off, nor at high or low threshold settings. This is making me question whether the NB is working at all. Any thoughts? 73 -- Joe KB8AP _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Joe Planisky wrote:
> Hey folks, > > I've recently started picking up relatively strong pulses at 1 second > intervals on my K2. I suspect they're coming from a new electric fence > somewhere in the neighborhood. But where they're coming from is > immaterial to my question. > > Should the KNB2 noise blanker be effective against this type of noise? > I've always thought that such impulse type noise was exactly what noise > blankers were supposed to work best on, but I hear no difference in the > pulses whether the NB is on or off, nor at high or low threshold > settings. This is making me question whether the NB is working at all. > > Any thoughts? Some electric fences produce wide pulses, so you should try using the NB2 setting. If that doesn't work, you might consider increasing one of the capacitors that determines the pulse width in the KNB2; if you go to <http://www.qslnet.de/member/la3za/K2/mod.html> and scroll down to the KNB2 section you will see a note about it. I think the appropriate modification is to increase C12, which affects the NB2 setting. It is 0.068 mf and you could try 0.1 mf. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: KNB2 vs. electric fence.
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In reply to this post by Joe Planisky
Hello Joe,
Turn on your preamp, and then try the NB. Sometimes the noise just needs to be stronger so that the NB can do it's thing. This has worked for me many times. 73, Dale WA8SRA Joe Planisky wrote: > Hey folks, > > I've recently started picking up relatively strong pulses at 1 second > intervals on my K2. I suspect they're coming from a new electric > fence somewhere in the neighborhood. But where they're coming from is > immaterial to my question. > > Should the KNB2 noise blanker be effective against this type of > noise? I've always thought that such impulse type noise was exactly > what noise blankers were supposed to work best on, but I hear no > difference in the pulses whether the NB is on or off, nor at high or > low threshold settings. This is making me question whether the NB is > working at all. > > Any thoughts? > > 73 > -- > Joe > KB8AP > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Thanks for the responses, Dale and Vic.
I tried increasing C12 to 0.1uF, no change. I tried turning on the preamp, again no change. I did some research on the web and it seems the effectiveness of the KNB2 has been the subject of some discussion in the past. A handful of folks even shared my suspicion that their KNB2 was not working at all. I was able to verify that my KNB2 was indeed working by connecting a short piece of wire to the antenna jack and scraping it against various metallic objects in the shack with the NB on and off. (I tried the light dimmer trick, but I must have the worlds quietest light dimmer. Never thought that would be a problem!) What did seem to help was the mod suggested by DL7MAJ: http://www.dl7maj.de/KNB2-Mod.pdf which adds a 0.1uF capacitor between the emitter of Q2 and ground. This increases the low-threshold sensitivity. Before, I never noticed any difference between the LEVEL=LO and LEVEL=HI settings. Now there is most definitely a difference and the LO setting takes out at least some of the pops. Thanks again for your responses. 73 -- Joe KB8AP On Aug 3, 2008, at 2:16 PM, Dale Boresz wrote: > > Turn on your preamp, and then try the NB. On Aug 3, 2008, at 2:07 PM, Vic K2VCO wrote: > > Some electric fences produce wide pulses, so you should try using > the NB2 setting. If that doesn't work, you might consider increasing > one of the capacitors that determines the pulse width in the KNB2; _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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My fence charger disappears best on the HI setting.. on most days... although there are a few days it likes to hold out for the LOW setting. Havn't tracked it yet to why. But suspect that humidity has a lot to do with it. --... ...--Dale - WC7S in Wy _________________________________________________________________ Your PC, mobile phone, and online services work together like never before. http://clk.atdmt.com/MRT/go/108587394/direct/01/_______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Joe Planisky
Good Day to all,
I have had prior problems with my neighbors electric fence used to contain his horses. I don't have much experience with the NB in the K2. i am using the K3 which does a wonderful job. I guess the first thing I would do is make sure the interference you are hearing is in fact the electric fence. Do this by isolating all of you equipment from your shack power source. If the problem persists, then I would turn off all power to your house and check if the problem is still there. If so, it is time to go mobile or portable with the K2 and an AM receiver. I think though I shoud first confirm that the fence is your neighbors or is it yours? If is your neighbors, I would suggest contacting them and nicely explaining the situation. When I did this, my neighbor was very cooperative. i explaind it as "MY Problem" and asked him for permission to access his property to explore for the problem. In my case the fence was located across the street and kiddie corner , approx. 500' away from my house. The fence covers appox. 5 acres. I found that the problem was somewhat "weather" dependent. An example was just after a good rain it would really take off. It seemd as possibly some large field grass or weeds would touch the fence and act as an antenna. Upon investigation, I found that the fence was badly neglected and had several open portions and very poor grounding. I asked my friendly neighbor to disconnect power from the fencing unit and guess what, the interference vanished. I then asked him if I could make some repairs to the fence and excplained my intentions, which I might add quickly included purchasing at my cost, a new electrice fence module. I proceeded the jump all connections that were hanging open in the fence circuit as well as remove the existing the grounding system which i might add consisted of a piece of 24G wire that was spliced several times terminating to nothing more that a large screwdriver that was shoved into the ground. This was all replaced and neetened up, and terminated with a nice new and shiny 8' ground rod. I plugged in the new power unit to see if all my efforts were helpful. To my amazement the problem was completely gone. Oh I forgot to mention, also pay close attemtion to all splices in the fence as well as the gate hooks that are sometimes used. The can arch over and act as quite the spark gap transmitter. I hope this gives you a place to start. Please reply with any further questions. 73's Mike N8XPQ
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In reply to this post by Joe Planisky
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In reply to this post by Joe Planisky
Joe:
I just ordered a KNB2 and looked at DL7MAJ's modification. In looking at the schematic, it seems like the shortest time constant for the one-shot is above 10 µs. The DL7 mod noted that Q2 was being loaded by the base of Q3 - possibly there is a load transient associated with charging C11,12. The 2222A has a fairly low beta, and Q3 has no RE, so its base current could be fairly high. Raising the beta seems like it would reduce the loading on Q2. I'll measure the beta on what comes with the KNB2. I've got 2n3904 (B=100) and 2n5089 (B=400), so I may substitute. The 5089 has a lower fT of 50 MHz, but for a 10µs pulsewidth, it should be fine. Steve NU7B
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Steve,
I suggest that you build the KNB2 first and see if it is effective for the noise you have to deal with. Normally, the gating level is not the problem, but the blanking pulse width can be varied (G3ULB mod) to handle other noise pulses. The stock KNB2 is quite effective for impulse noise of the automotive ignition type. Yes, if you have other types of noise sources that you must deal with, try either (or both) of these mods to see if it helps in your situation. Similarly, your proposed change for Q3 may make a difference too, so try it out. There is nothing wrong with a bit of experimentation. What I am encouraging you to do is build the KNB2 as "stock" first, and then experiment from there. The actual beta of several 2N2222As that I have measured is in the range of 100, so your proposed transistor change may make no difference. 73, Don W3FPR NU7B wrote: > Joe: > > I just ordered a KNB2 and looked at DL7MAJ's modification. In looking at the > schematic, it seems like the shortest time constant for the one-shot is > above 10 µs. The DL7 mod noted that Q2 was being loaded by the base of Q3 - > possibly there is a load transient associated with charging C11,12. The > 2222A has a fairly low beta, and Q3 has no RE, so its base current could be > fairly high. Raising the beta seems like it would reduce the loading on Q2. > > I'll measure the beta on what comes with the KNB2. I've got 2n3904 (B=100) > and 2n5089 (B=400), so I may substitute. The 5089 has a lower fT of 50 MHz, > but for a 10µs pulsewidth, it should be fine. > > Steve NU7B > > 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 |
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Are there a set of mods for the KNB1 similar to this? My TS450Sat had a
very effective noise blanker and the K3 works wonders on the noise at my home QTH but the K1 blanker could really use a bit more work. Not sure what it needs ATM but it could be fun trying to find it.. ~Brett On Wed, 2009-07-08 at 00:17 -0400, Don Wilhelm wrote: > Steve, > > I suggest that you build the KNB2 first and see if it is effective for > the noise you have to deal with. Normally, the gating level is not the > problem, but the blanking pulse width can be varied (G3ULB mod) to > handle other noise pulses. > > The stock KNB2 is quite effective for impulse noise of the automotive > ignition type. Yes, if you have other types of noise sources that you > must deal with, try either (or both) of these mods to see if it helps in > your situation. Similarly, your proposed change for Q3 may make a > difference too, so try it out. There is nothing wrong with a bit of > experimentation. What I am encouraging you to do is build the KNB2 as > "stock" first, and then experiment from there. The actual beta of > several 2N2222As that I have measured is in the range of 100, so your > proposed transistor change may make no difference. > > 73, > Don W3FPR > > NU7B wrote: > > Joe: > > > > I just ordered a KNB2 and looked at DL7MAJ's modification. In looking at the > > schematic, it seems like the shortest time constant for the one-shot is > > above 10 µs. The DL7 mod noted that Q2 was being loaded by the base of Q3 - > > possibly there is a load transient associated with charging C11,12. The > > 2222A has a fairly low beta, and Q3 has no RE, so its base current could be > > fairly high. Raising the beta seems like it would reduce the loading on Q2. > > > > I'll measure the beta on what comes with the KNB2. I've got 2n3904 (B=100) > > and 2n5089 (B=400), so I may substitute. The 5089 has a lower fT of 50 MHz, > > but for a 10µs pulsewidth, it should be fine. > > > > Steve NU7B > > > > > ______________________________________________________________ > 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 ______________________________________________________________ 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 |
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In reply to this post by Joe Planisky
Hi folks Interested to read the thead on electric fences. They are very common here around New Zealand, even in semi rural areas. The trick apparently is not the actual voltage which hurts, it's a gradual rise time which causes muscle contraction. I suspect this is why some fences are hard to knock out with the noise blanker. Certainly the high end devices in use down-under really pack a punch, and can supply energy to miles and miles of 5 wire fences. They are designed to simply burn off any grass or weeds which grow around the wires. My K2 works more or less on local fences, using low threshold. Sometimes it has very little effect. This could be related to pulse shape and width. Interestingly the K3 also is not so flash, the old Kenwood TS520S was a trooper in this dept. cheers paul b I've recently started picking up relatively strong pulses at 1 second intervals on my K2. I suspect they're coming from a new electric fence somewhere in the neighborhood. But where they're coming from is immaterial to my question. Should the KNB2 noise blanker be effective against this type of noise? I've always thought that such impulse type noise was exactly what noise blankers were supposed to work best on, but I hear no difference in the pulses whether the NB is on or off, nor at high or low threshold settings. This is making me question whether the NB is working at all. Any thoughts? 73 -- Joe KB8AP _______________________________________________ Elecra |
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In reply to this post by Brett Howard
My K2 has a KNB2, that works very well on my electric fence and on my neighbors. I can hear his fence shorting to the steel post, every pulse, mine is rather quiet that way, both are noisy at times to the radio.. until I turn on the NB... works better than any of the other NB that I have. Maybe the effectivness is the settings of the rx? --... ...-- Dale - WC7S in Wy > From: [hidden email] > To: [hidden email] > Date: Tue, 7 Jul 2009 21:43:26 -0700 > CC: [hidden email] > Subject: Re: [Elecraft] [K2] KNB2 vs. electric fence. > > Are there a set of mods for the KNB1 similar to this? My TS450Sat had a > very effective noise blanker and the K3 works wonders on the noise at my > home QTH but the K1 blanker could really use a bit more work. Not sure > what it needs ATM but it could be fun trying to find it.. > > ~Brett > > > On Wed, 2009-07-08 at 00:17 -0400, Don Wilhelm wrote: > > Steve, > > > > I suggest that you build the KNB2 first and see if it is effective for > > the noise you have to deal with. Normally, the gating level is not the > > problem, but the blanking pulse width can be varied (G3ULB mod) to > > handle other noise pulses. > > > > The stock KNB2 is quite effective for impulse noise of the automotive > > ignition type. Yes, if you have other types of noise sources that you > > must deal with, try either (or both) of these mods to see if it helps in > > your situation. Similarly, your proposed change for Q3 may make a > > difference too, so try it out. There is nothing wrong with a bit of > > experimentation. What I am encouraging you to do is build the KNB2 as > > "stock" first, and then experiment from there. The actual beta of > > several 2N2222As that I have measured is in the range of 100, so your > > proposed transistor change may make no difference. > > > > 73, > > Don W3FPR > > > > NU7B wrote: > > > Joe: > > > > > > I just ordered a KNB2 and looked at DL7MAJ's modification. In looking at the > > > schematic, it seems like the shortest time constant for the one-shot is > > > above 10 µs. The DL7 mod noted that Q2 was being loaded by the base of Q3 - > > > possibly there is a load transient associated with charging C11,12. The > > > 2222A has a fairly low beta, and Q3 has no RE, so its base current could be > > > fairly high. Raising the beta seems like it would reduce the loading on Q2. > > > > > > I'll measure the beta on what comes with the KNB2. I've got 2n3904 (B=100) > > > and 2n5089 (B=400), so I may substitute. The 5089 has a lower fT of 50 MHz, > > > but for a 10µs pulsewidth, it should be fine. > > > > > > Steve NU7B > > > > > > > > ______________________________________________________________ > > 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 > > ______________________________________________________________ > 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 _________________________________________________________________ Windows Live™: Keep your life in sync. http://windowslive.com/explore?ocid=TXT_TAGLM_WL_BR_life_in_synch_062009 ______________________________________________________________ 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 |
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