K3 Hum on Audio...
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When the sun rose today and it seems that my K3 decided to put some hum on my audio. During a quick SSB contact tonight on 80 meters I was told there was hum on my audio. This surprised me because yesterday I was involved in two different SSB QSOs where I was particularly interested in audio reports because I had just put the KPA500 on the air and wanted to know how it sounds. The audio reports yesterday, two different QSOs, were excellent. In fact one person wanted to know the rig because he said it sounded exceptional.
Well, tonight, I get a report of what sounds like (the other guy reported) 60 cycle hum on my audio. Now, absolutely NOTHING is different from yesterday, same configuration and all. So, I am thinking maybe it has something to do with the KPA500. So, I put that in Standby and the hum is still there on the audio. The mic is the MH2 hand mic plugged into the front of the K3. So, I switch to my Yamaha CM500 headset and mic plugged into the rear of the K3. No hum on that. So, the hum seems to do with the MH2 or maybe the front panel connection or something else. Does anyone know of what would cause this sudden thing and where I might go to scope out the problem? I would be more suspicious if it were some rig that was new to me, or some mic that was new or something. But, it is not new and until now I have always had excellent reports. Like I said, yesterday the KPA500 was put on the air for the first time but the reports were excellent reports on audio, this problem appeared today in fact, about 30 minutes ago. I turned the rig on at 6:15 PM and had the first QSO where the hum was reported at 6:25 PM. 73, phil, K7PEH ______________________________________________________________ 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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Ron,
I have been able to do more tests. Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic as in the MH2 but it is present. This morning I double checked all connections (most in the back). This includes the key out to the KPA500, the plugs for the cm500, the external speaker, my foot PTT switch, and even the svga cable to the KPA500. Nuts, have not tested the serial port yet. However, absolutely no difference in behavior. I can hear the hum on the speaker when I have the monitor gain cranked up a little bit and keying the mic in Test mode. If I lay my hand on the top of the K3 the hum disappears. If I lay my hand on the P3 sitting next to K3 the hum disappears but not as much. And, I can do the same with other grounded equipment. I have checked my grounds and they all seem to be pretty good. So, I am at a loss as to what to try next. This seemed to start on its own Wednesday afternoon after my last SSB QSO. I say that because after that QSO, I turned the rigs off and then the next day (Thursday, yesterday) I turned the rigs on and the hum was there on my first SSB QSO at 6:30 PM. It sure seems like a grounding problem but I am not sure where to check next. Also, this problem arose mysteriously close to me setting up the KPA500 which I put on the air for the first time Wednesday early afternoon, CW first and then a few SSB QSOs and I got good audio reports from both of those QSOs. The hum though is definite, if someone were listening to my audio with this hum they would hear it. 73, phil, K7PEH On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote: > Since it goes away when changing mics, it sounds a lot like a broken > connection in the microphone connector. I used to fix those by the dozens on > shipboard VHF radios, equipped with hand-held mics. The complaint would be > transmitting hum, no audio, or no PTT action, depending upon which wire > broke. > > Usually the break was at the connector, but sometimes it's in the mic, > depending upon which end had the best strain relief. Even found a broken > wire inside the cable on rare occasions. > > 73, > > Ron AC7AC > > -----Original Message----- > Subject: [Elecraft] K3 Hum on Audio... > > When the sun rose today and it seems that my K3 decided to put some hum on > my audio. During a quick SSB contact tonight on 80 meters I was told there > was hum on my audio. This surprised me because yesterday I was involved in > two different SSB QSOs where I was particularly interested in audio reports > because I had just put the KPA500 on the air and wanted to know how it > sounds. The audio reports yesterday, two different QSOs, were excellent. > In fact one person wanted to know the rig because he said it sounded > exceptional. > > Well, tonight, I get a report of what sounds like (the other guy reported) > 60 cycle hum on my audio. Now, absolutely NOTHING is different from > yesterday, same configuration and all. So, I am thinking maybe it has > something to do with the KPA500. So, I put that in Standby and the hum is > still there on the audio. The mic is the MH2 hand mic plugged into the > front of the K3. > > So, I switch to my Yamaha CM500 headset and mic plugged into the rear of the > K3. No hum on that. So, the hum seems to do with the MH2 or maybe the > front panel connection or something else. > > Does anyone know of what would cause this sudden thing and where I might go > to scope out the problem? I would be more suspicious if it were some rig > that was new to me, or some mic that was new or something. But, it is not > new and until now I have always had excellent reports. Like I said, > yesterday the KPA500 was put on the air for the first time but the reports > were excellent reports on audio, this problem appeared today in fact, about > 30 minutes ago. I turned the rig on at 6:15 PM and had the first QSO where > the hum was reported at 6:25 PM. > > 73, phil, K7PEH > > ______________________________________________________________ > 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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On 1/13/2012 9:20 AM, Phil Hystad wrote:
> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic as in the MH2 but it is present. Clarification question. Is it HUM (pure 60 Hz), or BUZZ (mostly harmonics of 60 Hz)? If it's HUM, I would suspect magnetic field coupling into the audio, either from a big power transformer (like the one in a power amp or a big linear power supply) or from a AC power wiring fault called a double-bonded neutral. The K3 has unshielded audio transformers at all the audio inputs and outputs, and an unshielded transformer is a sitting duck for magnetic fields. The good news is that the K3 has excellent audio equalization (TXEQ) that allows us to remove that 60 Hz hum by filtering. The lower audio frequencies in the human voice make NO useful contribution to speech intelligibility, but they do waste transmit power. So it is ALWAYS a good thing to set the TXEQ for maximum cut of the lowest two bands, and at least some cut of the third band. This is true with virtually ALL mics and ALL voices. AND it will reduce that hum enough that you may no longer hear it. There are several solutions to magnetic field coupling. 1) Rotate the noise source or the victim circuit to put the fields at right angles to the victim. 2) Move the noise source further from the victim. 3) If the hum field is produced by that AC power wiring error, fix the error to eliminate the field. 73, Jim K9YC ______________________________________________________________ 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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Jim,
Well, I would call it mostly a buzz. Also, the only near magnetic field of the KPA500 power transformer is off, I mean powered off and unplugged, so that does not seem to be the problem. I just ran another test with everything disconnected, including ground and coax. With the K3 in TEST mode, key-down on the mic still produces the hum. I double checked the grounds. I did this because if I were to touch anything metal on the k3, the metal part of the PL259 or the ground strap, the hum is damped quite a bit to almost insignificant. It seems that if my rig were already well grounded this would not happen so I am curious if this is something I would normally expect. I will experiment with the TXEQ but this is a real puzzle I would like to solve, not merely erase it. 73, phil On Jan 13, 2012, at 9:37 AM, Jim Brown wrote: > On 1/13/2012 9:20 AM, Phil Hystad wrote: >> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic as in the MH2 but it is present. > > Clarification question. Is it HUM (pure 60 Hz), or BUZZ (mostly > harmonics of 60 Hz)? If it's HUM, I would suspect magnetic field > coupling into the audio, either from a big power transformer (like the > one in a power amp or a big linear power supply) or from a AC power > wiring fault called a double-bonded neutral. > > The K3 has unshielded audio transformers at all the audio inputs and > outputs, and an unshielded transformer is a sitting duck for magnetic > fields. > > The good news is that the K3 has excellent audio equalization (TXEQ) > that allows us to remove that 60 Hz hum by filtering. The lower audio > frequencies in the human voice make NO useful contribution to speech > intelligibility, but they do waste transmit power. So it is ALWAYS a > good thing to set the TXEQ for maximum cut of the lowest two bands, and > at least some cut of the third band. This is true with virtually ALL > mics and ALL voices. AND it will reduce that hum enough that you may no > longer hear it. > > There are several solutions to magnetic field coupling. 1) Rotate the > noise source or the victim circuit to put the fields at right angles to > the victim. 2) Move the noise source further from the victim. 3) If the > hum field is produced by that AC power wiring error, fix the error to > eliminate the field. > > 73, Jim K9YC > ______________________________________________________________ > 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 Jim Brown-10
I'm fairly certain that there are no transformers being used on the mic inputs, only the line input (mono) and line outputs (stereo). Barry N1EU |
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In reply to this post by Jim Brown-10
I just did one more test. I hooked up my little 4-cell Li nano-phosphate battery to the input. Turned on the K3 and did the test again with the K3 in TEST mode. Same hum occurs. With this experiment, the only thing plugged into the K3 is the MH2 microphone itself and all AC in the room is switched off at the breaker. So, K3 on battery and it still has this hum. This is a bit perplexing. I am writing here on my laptop which is battery powered too.
73, phil On Jan 13, 2012, at 9:37 AM, Jim Brown wrote: > On 1/13/2012 9:20 AM, Phil Hystad wrote: >> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 mic as in the MH2 but it is present. > > Clarification question. Is it HUM (pure 60 Hz), or BUZZ (mostly > harmonics of 60 Hz)? If it's HUM, I would suspect magnetic field > coupling into the audio, either from a big power transformer (like the > one in a power amp or a big linear power supply) or from a AC power > wiring fault called a double-bonded neutral. > > The K3 has unshielded audio transformers at all the audio inputs and > outputs, and an unshielded transformer is a sitting duck for magnetic > fields. > > The good news is that the K3 has excellent audio equalization (TXEQ) > that allows us to remove that 60 Hz hum by filtering. The lower audio > frequencies in the human voice make NO useful contribution to speech > intelligibility, but they do waste transmit power. So it is ALWAYS a > good thing to set the TXEQ for maximum cut of the lowest two bands, and > at least some cut of the third band. This is true with virtually ALL > mics and ALL voices. AND it will reduce that hum enough that you may no > longer hear it. > > There are several solutions to magnetic field coupling. 1) Rotate the > noise source or the victim circuit to put the fields at right angles to > the victim. 2) Move the noise source further from the victim. 3) If the > hum field is produced by that AC power wiring error, fix the error to > eliminate the field. > > 73, Jim K9YC > ______________________________________________________________ > 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 |
Re: K3 Hum on Audio...
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In reply to this post by Phil Hystad-3
When the KPA500 is in standby, I assume that its AC mains is still
connected. Have you tried pulling the KPA500's mains plug to narrow the search? Is your P3 sitting between the KPA500 and the K3? 73, Geoff LX2AO On January 13, 2012, at 18:20 +0100, "Phil Hystad" <[hidden email]> wrote: <snip> > If I lay my hand on the top of the K3 the hum disappears. If I lay my > hand on the P3 sitting next to K3 the hum disappears but not as much. > And, I can do the same with other grounded equipment. I have checked my > grounds and they all seem to be pretty good. and earlier >> So, I am thinking maybe it has >> something to do with the KPA500. So, I put that in Standby and the hum >> is >> still there on the audio. The mic is the MH2 hand mic plugged into the >> front of the K3. ______________________________________________________________ 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 Barry N1EU
I would short all audio inputs to the K3 right at the connector input with everything disconnected except antenna. Key up radio in SSB and see if audio buzz is still there.
This test pretty much isolates the K3 George, W6GF Love my two K3s and awaiting my KX3 ________________________________ From: Barry N1EU <[hidden email]> To: Sent: Friday, January 13, 2012 9:58 AM Subject: Re: [Elecraft] K3 Hum on Audio... Jim Brown-10 wrote > > On 1/13/2012 9:20 AM, Phil Hystad wrote: >> Unfortunately, it is in both mics but not as strong in the Yamaha CM500 >> mic as in the MH2 but it is present. > > The K3 has unshielded audio transformers at all the audio inputs and > outputs, and an unshielded transformer is a sitting duck for magnetic > fields. > I'm fairly certain that there are no transformers being used on the mic inputs, only the line input (mono) and line outputs (stereo). Barry N1EU -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Hum-on-Audio-tp7182701p7184907.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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 Phil Hystad-3
Hi Phil,
I am no expert by any stretch of imagination if you follow my posts from my previous problems. So please take what I have to say as only a suggestion. Are all your external equipment grounds to a single point, this was major improvement in my shack. What I mean by single ground is the grounding lugs for every piece of equipment in my shack goes to one grounding point so everything should be at the same potential. Others who understand this more than I do will correct the implementation I am suggesting if I don't have it quite right. Cheers Don ~73 Don KD8NNU On Fri, Jan 13, 2012 at 12:20 PM, Phil Hystad wrote: > Ron, > > I have been able to do more tests. Unfortunately, it is in both mics > but not as strong in the Yamaha CM500 mic as in the MH2 but it is > present. > > This morning I double checked all connections (most in the back). > This includes the key out to the KPA500, the plugs for the cm500, the > external speaker, my foot PTT switch, and even the svga cable to the > KPA500. Nuts, have not tested the serial port yet. However, > absolutely no difference in behavior. I can hear the hum on the > speaker when I have the monitor gain cranked up a little bit and > keying the mic in Test mode. > > If I lay my hand on the top of the K3 the hum disappears. If I lay my > hand on the P3 sitting next to K3 the hum disappears but not as much. > And, I can do the same with other grounded equipment. I have checked > my grounds and they all seem to be pretty good. > > So, I am at a loss as to what to try next. This seemed to start on > its own Wednesday afternoon after my last SSB QSO. I say that because > after that QSO, I turned the rigs off and then the next day (Thursday, > yesterday) I turned the rigs on and the hum was there on my first SSB > QSO at 6:30 PM. > > It sure seems like a grounding problem but I am not sure where to > check next. Also, this problem arose mysteriously close to me setting > up the KPA500 which I put on the air for the first time Wednesday > early afternoon, CW first and then a few SSB QSOs and I got good audio > reports from both of those QSOs. The hum though is definite, if > someone were listening to my audio with this hum they would hear it. > > 73, phil, K7PEH > > > On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote: > >> Since it goes away when changing mics, it sounds a lot like a broken >> connection in the microphone connector. I used to fix those by the >> dozens on >> shipboard VHF radios, equipped with hand-held mics. The complaint >> would be >> transmitting hum, no audio, or no PTT action, depending upon which >> wire >> broke. >> Usually the break was at the connector, but sometimes it's in the >> mic, >> depending upon which end had the best strain relief. Even found a >> broken >> wire inside the cable on rare occasions. >> 73, >> >> Ron AC7AC >> >> -----Original Message----- >> Subject: [Elecraft] K3 Hum on Audio... >> >> When the sun rose today and it seems that my K3 decided to put some >> hum on >> my audio. During a quick SSB contact tonight on 80 meters I was told >> there >> was hum on my audio. This surprised me because yesterday I was >> involved in >> two different SSB QSOs where I was particularly interested in audio >> reports >> because I had just put the KPA500 on the air and wanted to know how >> it >> sounds. The audio reports yesterday, two different QSOs, were >> excellent. >> In fact one person wanted to know the rig because he said it sounded >> exceptional. >> >> Well, tonight, I get a report of what sounds like (the other guy >> reported) >> 60 cycle hum on my audio. Now, absolutely NOTHING is different from >> yesterday, same configuration and all. So, I am thinking maybe it >> has >> something to do with the KPA500. So, I put that in Standby and the >> hum is >> still there on the audio. The mic is the MH2 hand mic plugged into >> the >> front of the K3. >> >> So, I switch to my Yamaha CM500 headset and mic plugged into the rear >> of the >> K3. No hum on that. So, the hum seems to do with the MH2 or maybe >> the >> front panel connection or something else. >> >> Does anyone know of what would cause this sudden thing and where I >> might go >> to scope out the problem? I would be more suspicious if it were some >> rig >> that was new to me, or some mic that was new or something. But, it >> is not >> new and until now I have always had excellent reports. Like I said, >> yesterday the KPA500 was put on the air for the first time but the >> reports >> were excellent reports on audio, this problem appeared today in fact, >> about >> 30 minutes ago. I turned the rig on at 6:15 PM and had the first QSO >> where >> the hum was reported at 6:25 PM. >> >> 73, phil, K7PEH >> >> ______________________________________________________________ >> 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 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 Jim Brown-10
Hi,
Equipment with non-ferrous enclosures are vulnerable to picking up magnetic fields from linear power supplies. I found this out with my TT Corsair II, and the solution was to put the power supply on the other side of the radio, away from the audio circuitry. The steel cabinets of the other manufacturers have some advantages. 73 Tim GM4LMH ______________________________________________________________ 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 Geoffrey Mackenzie-Kennedy-3
As noted in a previous post, I disconnected EVERYTHING. Nothing on the back panel of the K3 at all except for a Li-nano-phosphate battery as my power source. All AC off at the breaker panel for this room. The only electrical equipment on was my K3 via the battery and my Macbook Pro laptop via its battery.
Given those conditions, the hum was still there. Jim Brown suggested that I consider TXEQ to cut off the low frequencies, I did max cut for all frequencies up to 400 Hz. The hum did not start being attenuated until 400 Hz cut. But, max cut on 400 Hz did not attenuate it completely. I did not do higher frequencies. So, anyone who might help -- where does this hum or buzz come from if nothing is connected to the K3 and there is no AC flowing anywhere in the room. It is 28 degrees outside, which is freezing cold plus for the northwest and I am not used to that but my next step is to go outside and check my grounding to ground points. phil On Jan 13, 2012, at 10:03 AM, Geoffrey Mackenzie-Kennedy wrote: > When the KPA500 is in standby, I assume that its AC mains is still connected. Have you tried pulling the KPA500's mains plug to narrow > the search? > > Is your P3 sitting between the KPA500 and the K3? > > 73, > Geoff > LX2AO > > On January 13, 2012, at 18:20 +0100, "Phil Hystad" <[hidden email]> wrote: > > <snip> > >> If I lay my hand on the top of the K3 the hum disappears. If I lay my hand on the P3 sitting next to K3 the hum disappears but not as much. And, I can do the same with other grounded equipment. I have checked my grounds and they all seem to be pretty good. > > and earlier > >>> So, I am thinking maybe it has >>> something to do with the KPA500. So, I put that in Standby and the hum is >>> still there on the audio. The mic is the MH2 hand mic plugged into the >>> front of the K3. > ______________________________________________________________ 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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I've been ignoring this thread, but your last post piqued my interest.
Several questions require answers before I can go on. Just note that while we tend to concentrate on the last new thing, the "workbench" and instruments and their connections have far too often been the entire problem. You would CERTAINLY NOT be the first, nor the last, to suffer from this as some issues are ghastly subtle. 1) What frequency is the hum. 2) By what means are you detecting the hum? Speaker? Line out to spectral audio program or some such on the Macbook? Other means? Other means, describe the method and connections in boring detail. It is critically important to precisely understand the means of measurement. 3) If detecting the hum on the Macbook, what level is the hum? 4) If detecting the hum on the Macbook, describe the connection between the K3 and the Macbook in boring detail. 73, Guy. On Fri, Jan 13, 2012 at 1:30 PM, Phil Hystad <[hidden email]> wrote: > As noted in a previous post, I disconnected EVERYTHING. Nothing on the > back panel of the K3 at all except for a Li-nano-phosphate battery as my > power source. All AC off at the breaker panel for this room. The only > electrical equipment on was my K3 via the battery and my Macbook Pro laptop > via its battery. > > Given those conditions, the hum was still there. > > Jim Brown suggested that I consider TXEQ to cut off the low frequencies, > I did max cut for all frequencies up to 400 Hz. The hum did not start > being attenuated until 400 Hz cut. But, max cut on 400 Hz did not > attenuate it completely. I did not do higher frequencies. > > So, anyone who might help -- where does this hum or buzz come from if > nothing is connected to the K3 and there is no AC flowing anywhere in the > room. It is 28 degrees outside, which is freezing cold plus for the > northwest and I am not used to that but my next step is to go outside and > check my grounding to ground points. > > phil > > > > On Jan 13, 2012, at 10:03 AM, Geoffrey Mackenzie-Kennedy wrote: > > > When the KPA500 is in standby, I assume that its AC mains is still > connected. Have you tried pulling the KPA500's mains plug to narrow > > the search? > > > > Is your P3 sitting between the KPA500 and the K3? > > > > 73, > > Geoff > > LX2AO > > > > On January 13, 2012, at 18:20 +0100, "Phil Hystad" <[hidden email]> > wrote: > > > > <snip> > > > >> If I lay my hand on the top of the K3 the hum disappears. If I lay my > hand on the P3 sitting next to K3 the hum disappears but not as much. And, > I can do the same with other grounded equipment. I have checked my grounds > and they all seem to be pretty good. > > > > and earlier > > > >>> So, I am thinking maybe it has > >>> something to do with the KPA500. So, I put that in Standby and the > hum is > >>> still there on the audio. The mic is the MH2 hand mic plugged into the > >>> front of the K3. > > > > ______________________________________________________________ > 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 Phil Hystad-3
Ron,
OK, now it appears I was mistaken when I said that that the hum was in both mics. I think I flubbed something up in my previous test due to the way that the macros are assigned to keys which led me to thinking that the hum occurred in both mics. But, I learned something in this... One, don't try to use one of your macro assigned keys (in my case M2 and M1) while in the menu because that merely reassigns the key to the new menu entry. I made this mistake several times this morning. But, when I discovered it and then reset my macro definitions, I rediscovered that the HUM occurs in the front panel MH2 hand held mic only. I did this test several times to make sure I was not confusing things. I discovered something else that I did not know before. PTT is actuated by any of the methods of PTT. So, when I thought I had the headphones CM500 mic enabled I used my foot switch for push to talk and since that worked for some dumb reason I was thinking I had successfully switched from front panel to rear panel. But, I had not. I also discovered that I could use the hand mic (front panel) PTT switch even though my rear panel mic was being used. Now, after I discovered this, I realize that it is obvious but something that lead to my confusion. So, the problem occurs on the FRONT PANEL mic only and not the rear panel. And, the problem occurs when the K3 is in TOTAL isolation from all AC sources except for possibly me. I mean, I am holding the mic but then I don't think that is a cause of the hum because I tried it with a insulated hand and it still caused the hum on the front panel mic. I doubt that this is caused by wall-outlet type AC because I have erased all AC for some of my tests. And, besides, this problem seemed to occur .... OK, while writing that last sentence something occurred to me. Another change I had made on Wednesday after I had my good audio reports on the MH2 front panel mic was that I set the configuration for the band specific power levels to work with the KPA500. So, I just now went to test the mic and change that setting around but the hum is gone. I repeat, the hum is gone from the front panel mic. I now can't test the band specific power menu setting because I have no problem. But, I have a suspicion as to the cause now and I am going to do some other experiments. 73, phil On Jan 13, 2012, at 10:15 AM, Ron D'Eau Claire wrote: > Yeah, Phil, two mics doing it eliminates the easy idea of a bad wire in one > of them. > > When switching mics, be sure to physically disconnect the one you are not > using. An ungrounded mic hot lead might introduce hum, even if you have the > other mic enabled. > > Hand effects suggest a ground loop- either AC or RF. Being in TEST mode > eliminates RF, since you aren't making any. > > I'd start disconnecting things one at a time. If the hum is still there with > everything but the mic and power supply connected, you can be sure it's not > in the external gear. > > Do you have another power supply you can substitute? All it needs to do is > provide enough current for receive, since you are "transmitting" in TEST > mode. One possibility is that you'd lost filtering in the power supply. That > can produce different levels of hum from different mics, depending upon the > gain settings, etc. > > If it's clean on the alternate power supply, that leaves ONLY the K3, of > course. > > 73, > > Ron AC7AC > > -----Original Message----- > From: Phil Hystad [mailto:[hidden email]] > Sent: Friday, January 13, 2012 9:21 AM > To: Ron D'Eau Claire > Cc: 'Elecraft List' > Subject: Re: [Elecraft] K3 Hum on Audio... > > Ron, > > I have been able to do more tests. Unfortunately, it is in both mics but > not as strong in the Yamaha CM500 mic as in the MH2 but it is present. > > This morning I double checked all connections (most in the back). This > includes the key out to the KPA500, the plugs for the cm500, the external > speaker, my foot PTT switch, and even the svga cable to the KPA500. Nuts, > have not tested the serial port yet. However, absolutely no difference in > behavior. I can hear the hum on the speaker when I have the monitor gain > cranked up a little bit and keying the mic in Test mode. > > If I lay my hand on the top of the K3 the hum disappears. If I lay my hand > on the P3 sitting next to K3 the hum disappears but not as much. And, I can > do the same with other grounded equipment. I have checked my grounds and > they all seem to be pretty good. > > So, I am at a loss as to what to try next. This seemed to start on its own > Wednesday afternoon after my last SSB QSO. I say that because after that > QSO, I turned the rigs off and then the next day (Thursday, yesterday) I > turned the rigs on and the hum was there on my first SSB QSO at 6:30 PM. > > It sure seems like a grounding problem but I am not sure where to check > next. Also, this problem arose mysteriously close to me setting up the > KPA500 which I put on the air for the first time Wednesday early afternoon, > CW first and then a few SSB QSOs and I got good audio reports from both of > those QSOs. The hum though is definite, if someone were listening to my > audio with this hum they would hear it. > > 73, phil, K7PEH > > > On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote: > >> Since it goes away when changing mics, it sounds a lot like a broken >> connection in the microphone connector. I used to fix those by the dozens > on >> shipboard VHF radios, equipped with hand-held mics. The complaint would be >> transmitting hum, no audio, or no PTT action, depending upon which wire >> broke. >> >> Usually the break was at the connector, but sometimes it's in the mic, >> depending upon which end had the best strain relief. Even found a broken >> wire inside the cable on rare occasions. >> >> 73, >> >> Ron AC7AC >> >> -----Original Message----- >> Subject: [Elecraft] K3 Hum on Audio... >> >> When the sun rose today and it seems that my K3 decided to put some hum on >> my audio. During a quick SSB contact tonight on 80 meters I was told > there >> was hum on my audio. This surprised me because yesterday I was involved > in >> two different SSB QSOs where I was particularly interested in audio > reports >> because I had just put the KPA500 on the air and wanted to know how it >> sounds. The audio reports yesterday, two different QSOs, were excellent. >> In fact one person wanted to know the rig because he said it sounded >> exceptional. >> >> Well, tonight, I get a report of what sounds like (the other guy reported) >> 60 cycle hum on my audio. Now, absolutely NOTHING is different from >> yesterday, same configuration and all. So, I am thinking maybe it has >> something to do with the KPA500. So, I put that in Standby and the hum is >> still there on the audio. The mic is the MH2 hand mic plugged into the >> front of the K3. >> >> So, I switch to my Yamaha CM500 headset and mic plugged into the rear of > the >> K3. No hum on that. So, the hum seems to do with the MH2 or maybe the >> front panel connection or something else. >> >> Does anyone know of what would cause this sudden thing and where I might > go >> to scope out the problem? I would be more suspicious if it were some rig >> that was new to me, or some mic that was new or something. But, it is not >> new and until now I have always had excellent reports. Like I said, >> yesterday the KPA500 was put on the air for the first time but the reports >> were excellent reports on audio, this problem appeared today in fact, > about >> 30 minutes ago. I turned the rig on at 6:15 PM and had the first QSO > where >> the hum was reported at 6:25 PM. >> >> 73, phil, K7PEH >> >> ______________________________________________________________ >> 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 Guy, K2AV
Guy,
Thanks for not ignoring my problem any more and lending a hand :-) Answers to your 1) 2) 3) 4) questions below... On Jan 13, 2012, at 11:09 AM, Guy Olinger K2AV wrote: > I've been ignoring this thread, but your last post piqued my interest. > > Several questions require answers before I can go on. Just note that while we tend to concentrate on the last new thing, the "workbench" and instruments and their connections have far too often been the entire problem. You would CERTAINLY NOT be the first, nor the last, to suffer from this as some issues are ghastly subtle. > > 1) What frequency is the hum. Well, I am not good at guessing the frequency but it does sound like AC power type hum, maybe a little higher but I am just guessing. > 2) By what means are you detecting the hum? Speaker? Line out to spectral audio program or some such on the Macbook? Other means? Other means, describe the method and connections in boring detail. It is critically important to precisely understand the means of measurement. Hum is detected in all (I repeat ALL) audio outputs. These include my West Mountain COMspkr, and it includes the internal K3 speaker when the COMspkr is unplugged, and it includes my Yamaha CM500 headphones. It does not include my Macbook though -- I do not use my computers with the computer in any fashion (no DATA, no Audio, no speaker use, no application programs except for the K3, P3, and KPA500 utility programs). > 3) If detecting the hum on the Macbook, what level is the hum? Not detected on Macbook -- Macbook is 8 feet away and not connected to rigs in any way. > 4) If detecting the hum on the Macbook, describe the connection between the K3 and the Macbook in boring detail. See above. > > 73, Guy. > > On Fri, Jan 13, 2012 at 1:30 PM, Phil Hystad <[hidden email]> wrote: > As noted in a previous post, I disconnected EVERYTHING. Nothing on the back panel of the K3 at all except for a Li-nano-phosphate battery as my power source. All AC off at the breaker panel for this room. The only electrical equipment on was my K3 via the battery and my Macbook Pro laptop via its battery. > > Given those conditions, the hum was still there. > > Jim Brown suggested that I consider TXEQ to cut off the low frequencies, I did max cut for all frequencies up to 400 Hz. The hum did not start being attenuated until 400 Hz cut. But, max cut on 400 Hz did not attenuate it completely. I did not do higher frequencies. > > So, anyone who might help -- where does this hum or buzz come from if nothing is connected to the K3 and there is no AC flowing anywhere in the room. It is 28 degrees outside, which is freezing cold plus for the northwest and I am not used to that but my next step is to go outside and check my grounding to ground points. > > phil > > > > On Jan 13, 2012, at 10:03 AM, Geoffrey Mackenzie-Kennedy wrote: > > > When the KPA500 is in standby, I assume that its AC mains is still connected. Have you tried pulling the KPA500's mains plug to narrow > > the search? > > > > Is your P3 sitting between the KPA500 and the K3? > > > > 73, > > Geoff > > LX2AO > > > > On January 13, 2012, at 18:20 +0100, "Phil Hystad" <[hidden email]> wrote: > > > > <snip> > > > >> If I lay my hand on the top of the K3 the hum disappears. If I lay my hand on the P3 sitting next to K3 the hum disappears but not as much. And, I can do the same with other grounded equipment. I have checked my grounds and they all seem to be pretty good. > > > > and earlier > > > >>> So, I am thinking maybe it has > >>> something to do with the KPA500. So, I put that in Standby and the hum is > >>> still there on the audio. The mic is the MH2 hand mic plugged into the > >>> front of the K3. > > > > ______________________________________________________________ > 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 Phil Hystad-3
Ron,
Well, I just had a quick SSB chat with Clyde (AA7WC) (pre Noon Time net on 40 meters) and asked specifically for audio report with possible hum. His report was no hum, clear good sounding audio, with S7 signal. So I am suspicious of my florescent lights in the garage although they are on right now with no hum. I am thinking though that maybe there is something intermittent with those lights. But, then again, the "something loose in the mic cord" maybe be the cause too. But, I jiggled that cord and connection and so on quite vigorously before when I had the hum and it did not change the hum status. Then, when the hum disappeared, I did those jiggle the cord and connector on the mic tests again and the hum DID NOT come back. Wow, I can't believe I have spent the entire morning fooling around with this. I even called into work and said that I was not coming in today just to work on this problem. I don't really want to go outside anyway despite that the temperature has now risen to a toasty 36 degrees. 73, phil, K7PEH On Jan 13, 2012, at 11:23 AM, Ron D'Eau Claire wrote: > Good luck Phil. That last part really suggests something loose in the mike > cord as I suggested at first. > > Ron AC7AC > > -----Original Message----- > Ron, > > OK, now it appears I was mistaken when I said that that the hum was in both > mics. I think I flubbed something up in my previous test due to the way > that the macros are assigned to keys which led me to thinking that the hum > occurred in both mics. But, I learned something in this... > > One, don't try to use one of your macro assigned keys (in my case M2 and M1) > while in the menu because that merely reassigns the key to the new menu > entry. I made this mistake several times this morning. But, when I > discovered it and then reset my macro definitions, I rediscovered that the > HUM occurs in the front panel MH2 hand held mic only. I did this test > several times to make sure I was not confusing things. > > I discovered something else that I did not know before. PTT is actuated by > any of the methods of PTT. So, when I thought I had the headphones CM500 > mic enabled I used my foot switch for push to talk and since that worked for > some dumb reason I was thinking I had successfully switched from front panel > to rear panel. But, I had not. I also discovered that I could use the hand > mic (front panel) PTT switch even though my rear panel mic was being used. > Now, after I discovered this, I realize that it is obvious but something > that lead to my confusion. > > So, the problem occurs on the FRONT PANEL mic only and not the rear panel. > And, the problem occurs when the K3 is in TOTAL isolation from all AC > sources except for possibly me. I mean, I am holding the mic but then I > don't think that is a cause of the hum because I tried it with a insulated > hand and it still caused the hum on the front panel mic. > > I doubt that this is caused by wall-outlet type AC because I have erased all > AC for some of my tests. And, besides, this problem seemed to occur .... > > OK, while writing that last sentence something occurred to me. Another > change I had made on Wednesday after I had my good audio reports on the MH2 > front panel mic was that I set the configuration for the band specific power > levels to work with the KPA500. So, I just now went to test the mic and > change that setting around but the hum is gone. > > I repeat, the hum is gone from the front panel mic. I now can't test the > band specific power menu setting because I have no problem. > > But, I have a suspicion as to the cause now and I am going to do some other > experiments. > > 73, phil > ______________________________________________________________ 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 Phil Hystad-3
Is it possible that in setting the power level, you accidentally turned
up the compression? (they are on the same knob). If the compression is too high it will make a rushing, buzzing sound on the audio Buck k4ia On 1/13/2012 2:09 PM, Phil Hystad wrote: > Ron, > > OK, now it appears I was mistaken when I said that that the hum was in both mics. I think I flubbed something up in my previous test due to the way that the macros are assigned to keys which led me to thinking that the hum occurred in both mics. But, I learned something in this... > > One, don't try to use one of your macro assigned keys (in my case M2 and M1) while in the menu because that merely reassigns the key to the new menu entry. I made this mistake several times this morning. But, when I discovered it and then reset my macro definitions, I rediscovered that the HUM occurs in the front panel MH2 hand held mic only. I did this test several times to make sure I was not confusing things. > > I discovered something else that I did not know before. PTT is actuated by any of the methods of PTT. So, when I thought I had the headphones CM500 mic enabled I used my foot switch for push to talk and since that worked for some dumb reason I was thinking I had successfully switched from front panel to rear panel. But, I had not. I also discovered that I could use the hand mic (front panel) PTT switch even though my rear panel mic was being used. Now, after I discovered this, I realize that it is obvious but something that lead to my confusion. > > So, the problem occurs on the FRONT PANEL mic only and not the rear panel. And, the problem occurs when the K3 is in TOTAL isolation from all AC sources except for possibly me. I mean, I am holding the mic but then I don't think that is a cause of the hum because I tried it with a insulated hand and it still caused the hum on the front panel mic. > > I doubt that this is caused by wall-outlet type AC because I have erased all AC for some of my tests. And, besides, this problem seemed to occur .... > > OK, while writing that last sentence something occurred to me. Another change I had made on Wednesday after I had my good audio reports on the MH2 front panel mic was that I set the configuration for the band specific power levels to work with the KPA500. So, I just now went to test the mic and change that setting around but the hum is gone. > > I repeat, the hum is gone from the front panel mic. I now can't test the band specific power menu setting because I have no problem. > > But, I have a suspicion as to the cause now and I am going to do some other experiments. > > 73, phil > > > On Jan 13, 2012, at 10:15 AM, Ron D'Eau Claire wrote: > >> Yeah, Phil, two mics doing it eliminates the easy idea of a bad wire in one >> of them. >> >> When switching mics, be sure to physically disconnect the one you are not >> using. An ungrounded mic hot lead might introduce hum, even if you have the >> other mic enabled. >> >> Hand effects suggest a ground loop- either AC or RF. Being in TEST mode >> eliminates RF, since you aren't making any. >> >> I'd start disconnecting things one at a time. If the hum is still there with >> everything but the mic and power supply connected, you can be sure it's not >> in the external gear. >> >> Do you have another power supply you can substitute? All it needs to do is >> provide enough current for receive, since you are "transmitting" in TEST >> mode. One possibility is that you'd lost filtering in the power supply. That >> can produce different levels of hum from different mics, depending upon the >> gain settings, etc. >> >> If it's clean on the alternate power supply, that leaves ONLY the K3, of >> course. >> >> 73, >> >> Ron AC7AC >> >> -----Original Message----- >> From: Phil Hystad [mailto:[hidden email]] >> Sent: Friday, January 13, 2012 9:21 AM >> To: Ron D'Eau Claire >> Cc: 'Elecraft List' >> Subject: Re: [Elecraft] K3 Hum on Audio... >> >> Ron, >> >> I have been able to do more tests. Unfortunately, it is in both mics but >> not as strong in the Yamaha CM500 mic as in the MH2 but it is present. >> >> This morning I double checked all connections (most in the back). This >> includes the key out to the KPA500, the plugs for the cm500, the external >> speaker, my foot PTT switch, and even the svga cable to the KPA500. Nuts, >> have not tested the serial port yet. However, absolutely no difference in >> behavior. I can hear the hum on the speaker when I have the monitor gain >> cranked up a little bit and keying the mic in Test mode. >> >> If I lay my hand on the top of the K3 the hum disappears. If I lay my hand >> on the P3 sitting next to K3 the hum disappears but not as much. And, I can >> do the same with other grounded equipment. I have checked my grounds and >> they all seem to be pretty good. >> >> So, I am at a loss as to what to try next. This seemed to start on its own >> Wednesday afternoon after my last SSB QSO. I say that because after that >> QSO, I turned the rigs off and then the next day (Thursday, yesterday) I >> turned the rigs on and the hum was there on my first SSB QSO at 6:30 PM. >> >> It sure seems like a grounding problem but I am not sure where to check >> next. Also, this problem arose mysteriously close to me setting up the >> KPA500 which I put on the air for the first time Wednesday early afternoon, >> CW first and then a few SSB QSOs and I got good audio reports from both of >> those QSOs. The hum though is definite, if someone were listening to my >> audio with this hum they would hear it. >> >> 73, phil, K7PEH >> >> >> On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote: >> >>> Since it goes away when changing mics, it sounds a lot like a broken >>> connection in the microphone connector. I used to fix those by the dozens >> on >>> shipboard VHF radios, equipped with hand-held mics. The complaint would be >>> transmitting hum, no audio, or no PTT action, depending upon which wire >>> broke. >>> >>> Usually the break was at the connector, but sometimes it's in the mic, >>> depending upon which end had the best strain relief. Even found a broken >>> wire inside the cable on rare occasions. >>> >>> 73, >>> >>> Ron AC7AC >>> >>> -----Original Message----- >>> Subject: [Elecraft] K3 Hum on Audio... >>> >>> When the sun rose today and it seems that my K3 decided to put some hum on >>> my audio. During a quick SSB contact tonight on 80 meters I was told >> there >>> was hum on my audio. This surprised me because yesterday I was involved >> in >>> two different SSB QSOs where I was particularly interested in audio >> reports >>> because I had just put the KPA500 on the air and wanted to know how it >>> sounds. The audio reports yesterday, two different QSOs, were excellent. >>> In fact one person wanted to know the rig because he said it sounded >>> exceptional. >>> >>> Well, tonight, I get a report of what sounds like (the other guy reported) >>> 60 cycle hum on my audio. Now, absolutely NOTHING is different from >>> yesterday, same configuration and all. So, I am thinking maybe it has >>> something to do with the KPA500. So, I put that in Standby and the hum is >>> still there on the audio. The mic is the MH2 hand mic plugged into the >>> front of the K3. >>> >>> So, I switch to my Yamaha CM500 headset and mic plugged into the rear of >> the >>> K3. No hum on that. So, the hum seems to do with the MH2 or maybe the >>> front panel connection or something else. >>> >>> Does anyone know of what would cause this sudden thing and where I might >> go >>> to scope out the problem? I would be more suspicious if it were some rig >>> that was new to me, or some mic that was new or something. But, it is not >>> new and until now I have always had excellent reports. Like I said, >>> yesterday the KPA500 was put on the air for the first time but the reports >>> were excellent reports on audio, this problem appeared today in fact, >> about >>> 30 minutes ago. I turned the rig on at 6:15 PM and had the first QSO >> where >>> the hum was reported at 6:25 PM. >>> >>> 73, phil, K7PEH >>> >>> ______________________________________________________________ >>> 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 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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Buck,
Good suggestion but that was one of the things that I checked earlier this morning when I had the hum on the mic. Both compression level and mic gain were the same that they always have been. 73, phil, K7PEH On Jan 13, 2012, at 12:02 PM, Buck - k4ia wrote: > Is it possible that in setting the power level, you accidentally turned > up the compression? (they are on the same knob). If the compression is > too high it will make a rushing, buzzing sound on the audio > > Buck > k4ia > > > On 1/13/2012 2:09 PM, Phil Hystad wrote: >> Ron, >> >> OK, now it appears I was mistaken when I said that that the hum was in both mics. I think I flubbed something up in my previous test due to the way that the macros are assigned to keys which led me to thinking that the hum occurred in both mics. But, I learned something in this... >> >> One, don't try to use one of your macro assigned keys (in my case M2 and M1) while in the menu because that merely reassigns the key to the new menu entry. I made this mistake several times this morning. But, when I discovered it and then reset my macro definitions, I rediscovered that the HUM occurs in the front panel MH2 hand held mic only. I did this test several times to make sure I was not confusing things. >> >> I discovered something else that I did not know before. PTT is actuated by any of the methods of PTT. So, when I thought I had the headphones CM500 mic enabled I used my foot switch for push to talk and since that worked for some dumb reason I was thinking I had successfully switched from front panel to rear panel. But, I had not. I also discovered that I could use the hand mic (front panel) PTT switch even though my rear panel mic was being used. Now, after I discovered this, I realize that it is obvious but something that lead to my confusion. >> >> So, the problem occurs on the FRONT PANEL mic only and not the rear panel. And, the problem occurs when the K3 is in TOTAL isolation from all AC sources except for possibly me. I mean, I am holding the mic but then I don't think that is a cause of the hum because I tried it with a insulated hand and it still caused the hum on the front panel mic. >> >> I doubt that this is caused by wall-outlet type AC because I have erased all AC for some of my tests. And, besides, this problem seemed to occur .... >> >> OK, while writing that last sentence something occurred to me. Another change I had made on Wednesday after I had my good audio reports on the MH2 front panel mic was that I set the configuration for the band specific power levels to work with the KPA500. So, I just now went to test the mic and change that setting around but the hum is gone. >> >> I repeat, the hum is gone from the front panel mic. I now can't test the band specific power menu setting because I have no problem. >> >> But, I have a suspicion as to the cause now and I am going to do some other experiments. >> >> 73, phil >> >> >> On Jan 13, 2012, at 10:15 AM, Ron D'Eau Claire wrote: >> >>> Yeah, Phil, two mics doing it eliminates the easy idea of a bad wire in one >>> of them. >>> >>> When switching mics, be sure to physically disconnect the one you are not >>> using. An ungrounded mic hot lead might introduce hum, even if you have the >>> other mic enabled. >>> >>> Hand effects suggest a ground loop- either AC or RF. Being in TEST mode >>> eliminates RF, since you aren't making any. >>> >>> I'd start disconnecting things one at a time. If the hum is still there with >>> everything but the mic and power supply connected, you can be sure it's not >>> in the external gear. >>> >>> Do you have another power supply you can substitute? All it needs to do is >>> provide enough current for receive, since you are "transmitting" in TEST >>> mode. One possibility is that you'd lost filtering in the power supply. That >>> can produce different levels of hum from different mics, depending upon the >>> gain settings, etc. >>> >>> If it's clean on the alternate power supply, that leaves ONLY the K3, of >>> course. >>> >>> 73, >>> >>> Ron AC7AC >>> >>> -----Original Message----- >>> From: Phil Hystad [mailto:[hidden email]] >>> Sent: Friday, January 13, 2012 9:21 AM >>> To: Ron D'Eau Claire >>> Cc: 'Elecraft List' >>> Subject: Re: [Elecraft] K3 Hum on Audio... >>> >>> Ron, >>> >>> I have been able to do more tests. Unfortunately, it is in both mics but >>> not as strong in the Yamaha CM500 mic as in the MH2 but it is present. >>> >>> This morning I double checked all connections (most in the back). This >>> includes the key out to the KPA500, the plugs for the cm500, the external >>> speaker, my foot PTT switch, and even the svga cable to the KPA500. Nuts, >>> have not tested the serial port yet. However, absolutely no difference in >>> behavior. I can hear the hum on the speaker when I have the monitor gain >>> cranked up a little bit and keying the mic in Test mode. >>> >>> If I lay my hand on the top of the K3 the hum disappears. If I lay my hand >>> on the P3 sitting next to K3 the hum disappears but not as much. And, I can >>> do the same with other grounded equipment. I have checked my grounds and >>> they all seem to be pretty good. >>> >>> So, I am at a loss as to what to try next. This seemed to start on its own >>> Wednesday afternoon after my last SSB QSO. I say that because after that >>> QSO, I turned the rigs off and then the next day (Thursday, yesterday) I >>> turned the rigs on and the hum was there on my first SSB QSO at 6:30 PM. >>> >>> It sure seems like a grounding problem but I am not sure where to check >>> next. Also, this problem arose mysteriously close to me setting up the >>> KPA500 which I put on the air for the first time Wednesday early afternoon, >>> CW first and then a few SSB QSOs and I got good audio reports from both of >>> those QSOs. The hum though is definite, if someone were listening to my >>> audio with this hum they would hear it. >>> >>> 73, phil, K7PEH >>> >>> >>> On Jan 13, 2012, at 8:12 AM, Ron D'Eau Claire wrote: >>> >>>> Since it goes away when changing mics, it sounds a lot like a broken >>>> connection in the microphone connector. I used to fix those by the dozens >>> on >>>> shipboard VHF radios, equipped with hand-held mics. The complaint would be >>>> transmitting hum, no audio, or no PTT action, depending upon which wire >>>> broke. >>>> >>>> Usually the break was at the connector, but sometimes it's in the mic, >>>> depending upon which end had the best strain relief. Even found a broken >>>> wire inside the cable on rare occasions. >>>> >>>> 73, >>>> >>>> Ron AC7AC >>>> >>>> -----Original Message----- >>>> Subject: [Elecraft] K3 Hum on Audio... >>>> >>>> When the sun rose today and it seems that my K3 decided to put some hum on >>>> my audio. During a quick SSB contact tonight on 80 meters I was told >>> there >>>> was hum on my audio. This surprised me because yesterday I was involved >>> in >>>> two different SSB QSOs where I was particularly interested in audio >>> reports >>>> because I had just put the KPA500 on the air and wanted to know how it >>>> sounds. The audio reports yesterday, two different QSOs, were excellent. >>>> In fact one person wanted to know the rig because he said it sounded >>>> exceptional. >>>> >>>> Well, tonight, I get a report of what sounds like (the other guy reported) >>>> 60 cycle hum on my audio. Now, absolutely NOTHING is different from >>>> yesterday, same configuration and all. So, I am thinking maybe it has >>>> something to do with the KPA500. So, I put that in Standby and the hum is >>>> still there on the audio. The mic is the MH2 hand mic plugged into the >>>> front of the K3. >>>> >>>> So, I switch to my Yamaha CM500 headset and mic plugged into the rear of >>> the >>>> K3. No hum on that. So, the hum seems to do with the MH2 or maybe the >>>> front panel connection or something else. >>>> >>>> Does anyone know of what would cause this sudden thing and where I might >>> go >>>> to scope out the problem? I would be more suspicious if it were some rig >>>> that was new to me, or some mic that was new or something. But, it is not >>>> new and until now I have always had excellent reports. Like I said, >>>> yesterday the KPA500 was put on the air for the first time but the reports >>>> were excellent reports on audio, this problem appeared today in fact, >>> about >>>> 30 minutes ago. I turned the rig on at 6:15 PM and had the first QSO >>> where >>>> the hum was reported at 6:25 PM. >>>> >>>> 73, phil, K7PEH >>>> >>>> ______________________________________________________________ >>>> 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 > ______________________________________________________________ > 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 Phil Hystad-3
so you unplug the mike input to K3 the hum goes away
when you plug into the K3 mike input the hum is there ? I would think you have a bad mike/cord/connecter Bob K3DJC On Fri, 13 Jan 2012 11:31:38 -0800 Phil Hystad <[hidden email]> writes: > Ron, > > Well, I just had a quick SSB chat with Clyde (AA7WC) (pre Noon Time > net on 40 meters) and asked specifically for audio report with > possible hum. His report was no hum, clear good sounding audio, > with S7 signal. > > So I am suspicious of my florescent lights in the garage although > they are on right now with no hum. I am thinking though that maybe > there is something intermittent with those lights. But, then again, > the "something loose in the mic cord" maybe be the cause too. But, > I jiggled that cord and connection and so on quite vigorously before > when I had the hum and it did not change the hum status. Then, when > the hum disappeared, I did those jiggle the cord and connector on > the mic tests again and the hum DID NOT come back. > > Wow, I can't believe I have spent the entire morning fooling around > with this. I even called into work and said that I was not coming > in today just to work on this problem. I don't really want to go > outside anyway despite that the temperature has now risen to a > toasty 36 degrees. > > 73, phil, K7PEH > > > On Jan 13, 2012, at 11:23 AM, Ron D'Eau Claire wrote: > > > Good luck Phil. That last part really suggests something loose in > the mike > > cord as I suggested at first. > > > > Ron AC7AC > > > > -----Original Message----- > > Ron, > > > > OK, now it appears I was mistaken when I said that that the hum > was in both > > mics. I think I flubbed something up in my previous test due to > the way > > that the macros are assigned to keys which led me to thinking that > the hum > > occurred in both mics. But, I learned something in this... > > > > One, don't try to use one of your macro assigned keys (in my case > M2 and M1) > > while in the menu because that merely reassigns the key to the new > menu > > entry. I made this mistake several times this morning. But, when > I > > discovered it and then reset my macro definitions, I rediscovered > that the > > HUM occurs in the front panel MH2 hand held mic only. I did this > test > > several times to make sure I was not confusing things. > > > > I discovered something else that I did not know before. PTT is > actuated by > > any of the methods of PTT. So, when I thought I had the > headphones CM500 > > mic enabled I used my foot switch for push to talk and since that > worked for > > some dumb reason I was thinking I had successfully switched from > front panel > > to rear panel. But, I had not. I also discovered that I could > use the hand > > mic (front panel) PTT switch even though my rear panel mic was > being used. > > Now, after I discovered this, I realize that it is obvious but > something > > that lead to my confusion. > > > > So, the problem occurs on the FRONT PANEL mic only and not the > rear panel. > > And, the problem occurs when the K3 is in TOTAL isolation from all > AC > > sources except for possibly me. I mean, I am holding the mic but > then I > > don't think that is a cause of the hum because I tried it with a > insulated > > hand and it still caused the hum on the front panel mic. > > > > I doubt that this is caused by wall-outlet type AC because I have > erased all > > AC for some of my tests. And, besides, this problem seemed to > occur .... > > > > OK, while writing that last sentence something occurred to me. > Another > > change I had made on Wednesday after I had my good audio reports > on the MH2 > > front panel mic was that I set the configuration for the band > specific power > > levels to work with the KPA500. So, I just now went to test the > mic and > > change that setting around but the hum is gone. > > > > I repeat, the hum is gone from the front panel mic. I now can't > test the > > band specific power menu setting because I have no problem. > > > > But, I have a suspicion as to the cause now and I am going to do > some other > > experiments. > > > > 73, phil > > > > ______________________________________________________________ > 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 > > ____________________________________________________________ Get Free Email with Video Mail & Video Chat! http://www.juno.com/freeemail?refcd=JUTAGOUT1FREM0210 ______________________________________________________________ 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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bob,
I am not sure if you understand my previous problems I was reporting. The hum has nothing to do with the mic plugged into the K3 or not (obvious if the mic is not plugged in, there is no problems). But, the hum comes with PTT transmit and not merely because the mic is plugged in. But, for some unusual reason, the hum is no longer there. But I fear it is waiting out there, maybe in the greenbelt behind our house, to make a sneak attack when I least expect it. 73, phil On Jan 13, 2012, at 12:09 PM, [hidden email] wrote: > so you unplug the mike input to K3 the hum goes away > when you plug into the K3 mike input the hum is there ? > I would think you have a bad mike/cord/connecter > > Bob K3DJC > > On Fri, 13 Jan 2012 11:31:38 -0800 Phil Hystad <[hidden email]> writes: >> Ron, >> >> Well, I just had a quick SSB chat with Clyde (AA7WC) (pre Noon Time >> net on 40 meters) and asked specifically for audio report with >> possible hum. His report was no hum, clear good sounding audio, >> with S7 signal. >> >> So I am suspicious of my florescent lights in the garage although >> they are on right now with no hum. I am thinking though that maybe >> there is something intermittent with those lights. But, then again, >> the "something loose in the mic cord" maybe be the cause too. But, >> I jiggled that cord and connection and so on quite vigorously before >> when I had the hum and it did not change the hum status. Then, when >> the hum disappeared, I did those jiggle the cord and connector on >> the mic tests again and the hum DID NOT come back. >> >> Wow, I can't believe I have spent the entire morning fooling around >> with this. I even called into work and said that I was not coming >> in today just to work on this problem. I don't really want to go >> outside anyway despite that the temperature has now risen to a >> toasty 36 degrees. >> >> 73, phil, K7PEH >> >> >> On Jan 13, 2012, at 11:23 AM, Ron D'Eau Claire wrote: >> >>> Good luck Phil. That last part really suggests something loose in >> the mike >>> cord as I suggested at first. >>> >>> Ron AC7AC >>> >>> -----Original Message----- >>> Ron, >>> >>> OK, now it appears I was mistaken when I said that that the hum >> was in both >>> mics. I think I flubbed something up in my previous test due to >> the way >>> that the macros are assigned to keys which led me to thinking that >> the hum >>> occurred in both mics. But, I learned something in this... >>> >>> One, don't try to use one of your macro assigned keys (in my case >> M2 and M1) >>> while in the menu because that merely reassigns the key to the new >> menu >>> entry. I made this mistake several times this morning. But, when >> I >>> discovered it and then reset my macro definitions, I rediscovered >> that the >>> HUM occurs in the front panel MH2 hand held mic only. I did this >> test >>> several times to make sure I was not confusing things. >>> >>> I discovered something else that I did not know before. PTT is >> actuated by >>> any of the methods of PTT. So, when I thought I had the >> headphones CM500 >>> mic enabled I used my foot switch for push to talk and since that >> worked for >>> some dumb reason I was thinking I had successfully switched from >> front panel >>> to rear panel. But, I had not. I also discovered that I could >> use the hand >>> mic (front panel) PTT switch even though my rear panel mic was >> being used. >>> Now, after I discovered this, I realize that it is obvious but >> something >>> that lead to my confusion. >>> >>> So, the problem occurs on the FRONT PANEL mic only and not the >> rear panel. >>> And, the problem occurs when the K3 is in TOTAL isolation from all >> AC >>> sources except for possibly me. I mean, I am holding the mic but >> then I >>> don't think that is a cause of the hum because I tried it with a >> insulated >>> hand and it still caused the hum on the front panel mic. >>> >>> I doubt that this is caused by wall-outlet type AC because I have >> erased all >>> AC for some of my tests. And, besides, this problem seemed to >> occur .... >>> >>> OK, while writing that last sentence something occurred to me. >> Another >>> change I had made on Wednesday after I had my good audio reports >> on the MH2 >>> front panel mic was that I set the configuration for the band >> specific power >>> levels to work with the KPA500. So, I just now went to test the >> mic and >>> change that setting around but the hum is gone. >>> >>> I repeat, the hum is gone from the front panel mic. I now can't >> test the >>> band specific power menu setting because I have no problem. >>> >>> But, I have a suspicion as to the cause now and I am going to do >> some other >>> experiments. >>> >>> 73, phil >>> >> >> ______________________________________________________________ >> 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 >> >> > > ____________________________________________________________ > Get Free Email with Video Mail & Video Chat! > http://www.juno.com/freeemail?refcd=JUTAGOUT1FREM0210 > ______________________________________________________________ > 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 Phil Hystad-3
Phil, which firmware version are you using? I was using the beta 4.47 and I developed audio problems the other night, After I deleted 4.47 and went back to the latest production firmware all was fine. Sorry if this has already been discussed - I just read this thread.
73 Bill NZ0T
On Fri, Jan 13, 2012 at 1:32 PM, Phil Hystad-3 [via Elecraft] <[hidden email]> wrote: Ron, |
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