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:[email protected]] >> 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:[email protected] >>> >>> 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:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
