KNB2 diagnosis
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I've never been convinced that my KNB2 worked as planned. I have the K2 open
today to install the K160RX, and decided to work on the KNB2. I found the archive messages about "scratching" Q21. I can only get any noise out of this with the pre-amp on - don't know if that's as expected or not. No setting of the NB changes the audio through the headphones. I can tap Q21 and get a pulse on my scope, or rub the case back and forth to get something a little more continuous (but still hard to capture on the scope - despite being quite evident in the headphones). Some of the time, my pulses just die at the output of R8, which goes to ground via L1. I'm not sure exactly what I do differently when the pulse gets past - perhaps just how hard I'm tapping? If I have the NB turned off, the signal stops at pin 4 of U1 - I see pulses there, but not at pin 1. If I have the NB turned on, pin 4 is biased and pin 1 is biased even higher - but I don't see the pulses at either pin. Help? Feeling stuck here. 73 de chris K6DBG _______________________________________________ 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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Chris,
I installed a KNB2 in my K2 a few months ago. I didn't think it worked until I tried the scratching of Q21 as recommended. With the top off and background noise coming from the speaker, I toggled from NB1 to NB2 to OFF while I scratched the case of Q21. It worked. I saw a definite difference. With the NB on I then toggled between both threshold levels and heard the difference also. Give this technique another try. Use a small screwdriver to scratch with. Good luck. John N2YC I've never been convinced that my KNB2 worked as planned. I have the K2 open today to install the K160RX, and decided to work on the KNB2. I found the archive messages about "scratching" Q21. I can only get any noise out of this with the pre-amp on - don't know if that's as expected or not. No setting of the NB changes the audio through the headphones. I can tap Q21 and get a pulse on my scope, or rub the case back and forth to get something a little more continuous (but still hard to capture on the scope - despite being quite evident in the headphones). Some of the time, my pulses just die at the output of R8, which goes to ground via L1. I'm not sure exactly what I do differently when the pulse gets past - perhaps just how hard I'm tapping? If I have the NB turned off, the signal stops at pin 4 of U1 - I see pulses there, but not at pin 1. If I have the NB turned on, pin 4 is biased and pin 1 is biased even higher - but I don't see the pulses at either pin. Help? Feeling stuck here.73 de chris K6DBG _______________________________________________ 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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I'll admit that I am pretty gullible, until I prove otherwise, but
scratching the top of a transistor as a fix???? Ha ha ha ha....c'mon now. Stan Rife W5EWA Houston, TX K2 S/N 4216 -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of [hidden email] Sent: Monday, December 24, 2007 11:18 PM To: [hidden email] Subject: Re: [Elecraft] KNB2 diagnosis Chris, I installed a KNB2 in my K2 a few months ago. I didn't think it worked until I tried the scratching of Q21 as recommended. With the top off and background noise coming from the speaker, I toggled from NB1 to NB2 to OFF while I scratched the case of Q21. It worked. I saw a definite difference. With the NB on I then toggled between both threshold levels and heard the difference also. Give this technique another try. Use a small screwdriver to scratch with. Good luck. John N2YC I've never been convinced that my KNB2 worked as planned. I have the K2 open today to install the K160RX, and decided to work on the KNB2. I found the archive messages about "scratching" Q21. I can only get any noise out of this with the pre-amp on - don't know if that's as expected or not. No setting of the NB changes the audio through the headphones. I can tap Q21 and get a pulse on my scope, or rub the case back and forth to get something a little more continuous (but still hard to capture on the scope - despite being quite evident in the headphones). Some of the time, my pulses just die at the output of R8, which goes to ground via L1. I'm not sure exactly what I do differently when the pulse gets past - perhaps just how hard I'm tapping? If I have the NB turned off, the signal stops at pin 4 of U1 - I see pulses there, but not at pin 1. If I have the NB turned on, pin 4 is biased and pin 1 is biased even higher - but I don't see the pulses at either pin. Help? Feeling stuck here.73 de chris K6DBG _______________________________________________ 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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Stan,
Scratching Q21 is certainly NOT a *fix* by any means!!! It is a 'GO -- NO-GO' test only. BUT it is one 'no-tools' method that can effectively produce the noise that the KNB2 is capable of suppressing. Of course, the preamp must be on to bring Q21 into the circuit. 73, Don W3FPR Stan Rife wrote: > I'll admit that I am pretty gullible, until I prove otherwise, but > scratching the top of a transistor as a fix???? Ha ha ha ha....c'mon now. > > > Stan Rife > W5EWA > Houston, TX > K2 S/N 4216 > > 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 srife
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In reply to this post by srife
To all I love my K2 it is a great radio,BUT the noise blanker well it sucks.
It works on some noise to some extent that's it. It is the weak point in the radio,and I live with it. I allways thought Elecraft would come up with a better design. 73 Sam kf4yox ----- Original Message ----- From: "Stan Rife" <[hidden email]> To: <[hidden email]> Sent: Wednesday, December 26, 2007 7:18 PM Subject: RE: [Elecraft] KNB2 diagnosis I'll admit that I am pretty gullible, until I prove otherwise, but scratching the top of a transistor as a fix???? Ha ha ha ha....c'mon now. Stan Rife W5EWA Houston, TX K2 S/N 4216 -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of [hidden email] Sent: Monday, December 24, 2007 11:18 PM To: [hidden email] Subject: Re: [Elecraft] KNB2 diagnosis Chris, I installed a KNB2 in my K2 a few months ago. I didn't think it worked until I tried the scratching of Q21 as recommended. With the top off and background noise coming from the speaker, I toggled from NB1 to NB2 to OFF while I scratched the case of Q21. It worked. I saw a definite difference. With the NB on I then toggled between both threshold levels and heard the difference also. Give this technique another try. Use a small screwdriver to scratch with. Good luck. John N2YC I've never been convinced that my KNB2 worked as planned. I have the K2 open today to install the K160RX, and decided to work on the KNB2. I found the archive messages about "scratching" Q21. I can only get any noise out of this with the pre-amp on - don't know if that's as expected or not. No setting of the NB changes the audio through the headphones. I can tap Q21 and get a pulse on my scope, or rub the case back and forth to get something a little more continuous (but still hard to capture on the scope - despite being quite evident in the headphones). Some of the time, my pulses just die at the output of R8, which goes to ground via L1. I'm not sure exactly what I do differently when the pulse gets past - perhaps just how hard I'm tapping? If I have the NB turned off, the signal stops at pin 4 of U1 - I see pulses there, but not at pin 1. If I have the NB turned on, pin 4 is biased and pin 1 is biased even higher - but I don't see the pulses at either pin. Help? Feeling stuck here.73 de chris K6DBG _______________________________________________ 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 _______________________________________________ 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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Samuel Strongin wrote:
> To all I love my K2 it is a great radio,BUT the noise blanker well it > sucks. It works on some noise to some extent that's it. It is the weak > point in the radio,and I live with it. I allways thought Elecraft would > come up with a better design. It sounds like you may be expecting the KNB2 to deal with types of noise it wasn't designed to handle. The "better design" you thought Elecraft would come up with already exists. It is known as the KDSP2. I think it has the noise handling features you are looking for. -- Cheers! Kevin. http://www.ve3syb.ca/ |"What are we going to do today, Borg?" Owner of Elecraft K2 #2172 |"Same thing we always do, Pinkutus: | Try to assimilate the world!" #include <disclaimer/favourite> | -Pinkutus & the Borg _______________________________________________ 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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