Question from a newbie
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I wonder if those that see no results from the KNB2 have forgotten to
remove a jumper or something? I could not operate without the KNB2. I have line noise that runs 20 dB over s9 at my location on 80 meters (almost as bad on 60, 40, 30, and 20) without the KNB2. Operations of any kind would be impractical. My Drake 2b receiver can only pick up the strongest stations. Message: 7 Date: Sun, 11 Mar 2007 06:42:55 -0700 (PDT) From: "Fred (FL)" <[hidden email]> Subject: RE: [Elecraft] Question from a newbie To: [hidden email] Message-ID: <[hidden email]> Content-Type: text/plain; charset=iso-8859-1 I built my K2 #54xx in May 06. Built the KNB2 Noise Blanker. Then found it never really seemed to work on any noise! One day, 4 cement trucks & 2 large pickups sat like 30 feet from my shack - all running, all working. The KNB2 did nothing to remove any of that man-made noise. Also it doesn't work on any band noise - that I ever found. I even got a 2nd KNB2, from Elecraft - and it didn't work either? The K2 itself - after build - operated true to all specs, calibrations, & alignments beautifully. I've since felt, the KNB2 is a design job left to be re-done, by some Elecraft designer, when they get around to it. The IC-7000's Noise Reduction and Noise Blanker circuitry - amazingly almost always reduces most band noises, real or imaginary, dramatically. Maybe in the K3? Fred N3CSY -- -bz- pardon my infinite ignorance. The set-of-things-I-do-not-know is infinite. 73 de N5BZ K2/100 # 5884 _______________________________________________ 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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Hi Bob:
>I wonder if those that see no results from the KNB2 have forgotten >to remove a jumper or something? > >I could not operate without the KNB2. > >I have line noise that runs 20 dB over s9 at my location on 80 >meters (almost as bad on 60, 40, 30, and 20) without the KNB2. >Operations of any kind would be impractical. Yesterday morning, I had some pretty horrendous line noise, which the KNB2 completely eliminated... then, in the afternoon I had what appeared to be the same noise (at least it SOUNDED the same to my ears), but the KNB2 couldn't do much at all. Same band, same RX settings, same antenna (and pointed in the same direction), same apparent direction of the noise, but something(!) had changed, to the point that the NB couldn't blank it adequately. Of course, the NB in my TS-950SD couldn't/didn't touch it either! But I agree that the KNB2, when it 'sees' an appropriate noise type, is WONDERFUL. 73, Tom N0SS _______________________________________________ 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: Question from a newbie > noise blanker
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with the FCC becoming more and more deaf to our pleas to fix broken
powerlines and the like ; wouldn't it be great for somebody ( hello Larry LP & Jack PAN) to make a NB widget hat was tunable width /depth and whatever parameters are needed...maybe using his PAN box to examine the junk ??? I know that the scopes on icoms can tell a bunch abt the pulse junk. AND the NB in the K2 still amazes me ... how well it does. bill At 07:17 AM 3/12/2007, Tom Hammond wrote: >Hi Bob: _______________________________________________ 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: Question from a newbie > noise blanker
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Perhaps something like the business end of an Evasive Noise Blanker? Jack's
PAN box would be a great addition for hunting the rubbish. 73, Geoff GM4ESD ----- Original Message ----- From: "Bill NY9H" <[hidden email]> To: "Tom Hammond" <[hidden email]>; <[hidden email]> Sent: Monday, March 12, 2007 1:38 PM Subject: Re: [Elecraft] Question from a newbie > noise blanker > with the FCC becoming more and more deaf to our pleas to fix broken > powerlines and the like ; wouldn't it be great for somebody ( hello Larry > LP & Jack PAN) > to make a NB widget hat was tunable width /depth and whatever parameters > are needed...maybe using his PAN box to examine the junk ??? > I know that the scopes on icoms can tell a bunch abt the pulse junk. > > _______________________________________________ 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: Question from a newbie > noise blanker
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Actually, a swept spectrum analyzer is a very difficult machine to use
for tracking noise, unless the sweep is triggered with the power line zero crossing. If you look at a pulsed waveform from broadband noise with a spectrum analyzer in free run mode (the normal operating mode) you may see some noise spikes drifting around, perhaps moving to the left on the screen; perhaps moving to the right. In the worst case, where the law of perversity applies, the spectrum analyzer's sweep rate will be such that no spikes are seen. If the noise is power line generated and hence has a rep rate of 2X line frequency, then switching the SA to line synch mode will cause the spikes to stand still. The reason for these effects is that a the spectrum of the gap-discharge noise is a line spectrum. If you hook an oscilloscope to a broadband receiver (such as the output of a Z10000 buffer amplifier on a K2's post-mixer stage) and if the interference is strong enough and the scope has enough gain (or an auxiliary broadband amplifier is employed) and you set the scope trigger to the power line, you can often see the RF pulse produced each multiple arc and ringing. (The arcs are extinguished every half-cycle in the ordinary case.) If one were to go about an effective noise blanker, I believe you could do much worse than building a new version of the old Collins approach -- a broadband receiver tuned to 30-35 MHz to detect noise and then a fast gate (with suitable delay for synchronization) to clip the received signal. The tunable subtraction units have, in my experience, highly variable effectiveness. I have one here and there are some noise sources that it will work with, but far more that it does not. My experience is that most power companies will fix problems, but they are often not well equipped or staffed to locate problems. The tools of the trade include a wide band receiver in a vehicle, a hand held AM receiver in the 200 MHz band with a built-in yagi, and an ultrasonic receiver with a parabolic dish. In the vehicle, drive around listening to the noise, and keep increasing the frequency as the higher the frequency, the shorter the distance over which it can be heard. If you are fortunate, this will localize it to a few poles (in really severe cases, you can hear the noise up to 600 or 800 MHz). Then, the hand held 200 MHz AM receiver and ultrasonic receiver are used to locate the specific pole or insulator. Like most things, it takes a bit of practice and experience, but the noise sources can be found. In my case, it took Dominion Resources 10 years to find and fix the problem that made it impossible for me to operate below 10 MHz, unless it rained. It turned out to be an arcing wavetrap on a 500 KV line, at a substation perhaps 5 miles from where I live. The 500 KV line runs about 800 feet in back of my antenna and Dominion's EMI techs kept looking for the problem on the transmission line near my house. After the main EMI boss retired, one of his former technicians was promoted and started the hunt from the beginning and zeroed in on the substation. Jack K8ZOA www.cliftonlaboratories.com Geoffrey Mackenzie-Kennedy wrote: > Perhaps something like the business end of an Evasive Noise Blanker? > Jack's PAN box would be a great addition for hunting the rubbish. > > 73, > > Geoff > GM4ESD > > ----- Original Message ----- From: "Bill NY9H" <[hidden email]> > To: "Tom Hammond" <[hidden email]>; <[hidden email]> > Sent: Monday, March 12, 2007 1:38 PM > Subject: Re: [Elecraft] Question from a newbie > noise blanker > > >> with the FCC becoming more and more deaf to our pleas to fix broken >> powerlines and the like ; wouldn't it be great for somebody ( hello >> Larry LP & Jack PAN) >> to make a NB widget hat was tunable width /depth and whatever >> parameters are needed...maybe using his PAN box to examine the junk ??? >> I know that the scopes on icoms can tell a bunch abt the pulse junk. >> >> > > _______________________________________________ > 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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Night vision goggles work quite well in some cases. I mentioned it to a
friend in the Guard and the 1st Sgt at the local armory decided to have a short training session. The troops spotted the two perpetrator insulators within 2 mins just by looking around. PG&E came out with their IR device in about a week, and it was fixed tFred K6DGW - Northern California Contest Club - CU in the 2007 CQP Oct 6-7 - www.cqp.orghe next day. YMMV _______________________________________________ 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: Question from a newbie > noise blanker
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Fred Jensen wrote:
> Night vision goggles work quite well in some cases. I mentioned it to > a friend in the Guard and the 1st Sgt at the local armory decided to > have a short training session. The troops spotted the two perpetrator > insulators within 2 mins just by looking around. PG&E came out with > their IR device in about a week, and it was fixed tFred K6DGW > - Northern California Contest Club > - CU in the 2007 CQP Oct 6-7 > - www.cqp.orghe next day. > > YMMV > Jack _______________________________________________ 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: Question from a newbie > noise blanker
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In reply to this post by k6dgw
Fred,
Was this at night? Do you think consumer grade ones would work? Tnx es 73, Leigh/WA5ZNU On Mon, 12 Mar 2007 11:58 am, Fred Jensen wrote: > Night vision goggles work quite well in some cases. I mentioned it to > a friend in the Guard and the 1st Sgt at the local armory decided to > have a short training session. The troops spotted the two perpetrator > insulators within 2 mins just by looking around. PG&E came out with > their IR device in about a week, and it was fixed tFred K6DGW _______________________________________________ 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: Question from a newbie > noise blanker
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There are two different types of night vision. Light amplification and
thermal imaging. Since the power company used IR to find the problem, the devices used were likely thermal imaging devices. Light amplifiers must have some light to work, and I don't believe they pick up thermal emissions. Many consumer devices are light amplifiers. David Wilburn [hidden email] K4DGW K2 #5982 Leigh L Klotz, Jr. wrote: > Fred, > Was this at night? Do you think consumer grade ones would work? > Tnx es 73, > Leigh/WA5ZNU > On Mon, 12 Mar 2007 11:58 am, Fred Jensen wrote: >> Night vision goggles work quite well in some cases. I mentioned it to >> a friend in the Guard and the 1st Sgt at the local armory decided to >> have a short training session. The troops spotted the two perpetrator >> insulators within 2 mins just by looking around. PG&E came out with >> their IR device in about a week, and it was fixed tFred K6DGW > _______________________________________________ > 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 |
Re: Question from a newbie > noise blanker
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In reply to this post by Jack Smith-6
Understood. I had been pondering a trigger derived from the noise receiver's
output pulses but with memory and variable delay added to freeze the display, and allow one or several output noise pulses to be displayed. Jack Smith wrote: > Actually, a swept spectrum analyzer is a very difficult machine to use for > tracking noise, unless the sweep is triggered with the power line zero > crossing. <snip> > If one were to go about an effective noise blanker, I believe you could > do much worse than building a new version of the old Collins approach -- > a broadband receiver tuned to 30-35 MHz to detect noise and then a fast > gate (with suitable delay for synchronization) to clip the received > signal. I agree and use a version. The old Collins system was first used in mobile installations I believe with the KWM-1, but the approach has undergone many changes over the years. Possibly the most significant changes that have evolved for HF use is to reduce the bandwidth of the noise receiver, and tune the noise receiver to a clear frequency close to the system's working frequency to get a more accurate sample of incoming noise. This mutation of the system has become known as the Evasive Noise Blanker, and in Amateur use the noise receiver is tuned to a clear frequency close to but outside of the band in use. From using this type of blanker system for many years I find that a noise receiver tuning range of 25 kHz above each operating band is satisfactory. I opted to avoid using a noise gate in the main receiver's signal chain in the interests of dynamic range, but use the noise pulses to inhibit a fast flip-flop which provides the H-Mode signal mixer with it 50% duty cycle LO squarewave injection, thus having the noise pulses switch injection. This type of blanker will not respond to legitimate in-band signals, a problem sometimes found during contests when using a blanker which samples in-band noise. 73, Geoff GM4ESD _______________________________________________ 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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