Took the mic connector apart, even the Heil mic (gasp!). Could find no short on the connecting wires, although I did clip out the unused posts in the 8-pin connector. Put it back together, connected it to the K3 and, miraculously, like Phil, the hum/buzz is gone. Have no idea what I did, just glad it's gone after only 30" of effort! Tnx for the help! 73, Cary, K4TM
Sent from my iPhone in Lynchburg VA - named a Runner Friendly City by Road Runner's Club of America in 2011. On Jan 23, 2012, at 11:28 AM, Phil Hystad <[email protected]> wrote: > Cary, > > I battled a hum/buzz problem just two weeks ago. After almost a full day > spent hunting, experimenting, searching, and doing everything under the sun > plus some very helpful dialog from others here on Elecraft forum, the > hum/buzz was finally fixed. > > I did not fix it, it just disappeared. So, here are some things I did... > > (1) I did all my tests with the monitor on and TX in TEST mode since that in > itself showed the hum/buzz. > > (2) With the help of Jim Brown (K9YC) I used the TX EQualization feature of > the K3 to crimp down to minimum > the low frequencies of the hum/buzz. Doing this, it appeared that this > was indeed a buzz and not a 60-cycle > hum because the buzz did not start to be attenuated until after the 400 > Hz TXEQ was set to zero and I started > working on the next higher frequency band. > > (3) I was confused as to whether this was front mic and back end mic inputs > or just front. I finally determined that > this was on the front mic only with 98 percent confidence. It is not > 100 percent confidence because all of my > experiments to prove one way or the other were a bit scrambled but I > think this was front panel mic only. > > (4) I then focused on the mic itself, an Elecraft MH2 hand mic. > Unfortunately it was the only mic I had for the front > panel but if you have more then one then I definitely suggest you test > them all to see if the hum/buzz is > independent of mic. > > (5) I jiggled and bumped this front panel mic and connector to see if there > was some loose connection. Someone > suggested florescent lighting as a noise generated and I tested with all > lights turned off (see next point). > > (6) I also had a nice 13.8 Li-nanoPhosphate battery so I disconnected > EVERYTHING from the K3. The only two > things connected were the 13.8 volt battery on the power and the mic on > the front panel. No Antenna, no > ground, no other connector to the K3. Hum/Buzz was still there and in > that test I also turned off the circuit > breaker for all AC in my shack. Did not help. > > (7) After some tests, and other things, the hum just seemed to disappear and > never came back since. My best > guess is that it was one of the following: (1) either an external noise > source that eventually turned off and > my front panel mic was just more susceptible to picking it up; or, (2) > the front panel mic itself had some kind > of loose connection that just seemed to finally correct itself. I favor > cause (1) though. I am kind of hoping it > comes back so I can test some more. > > 73, phil, K7PEH > > > On Jan 23, 2012, at 7:37 AM, Hunsdon Cary III wrote: > >> Don: >> You know it's hard to tell the difference between a buzz and a 60 hertz >> hum, at least to my 66 year old ears. HOWEVER, when I disconnected the mic >> front the front panel connector and used the XMIT button on the front panel, >> there is no buzz or hum! I'll start troubleshooting the mic cable now! >> Tnx for your help. >> 73, >> Cary, K4TM >> >> On Jan 23, 2012, at 10:23 AM, Don Wilhelm wrote: >> >>> Cary, >>> >>> Is it hum or is it actually "buzz"? Hum is 60 Hz AC, but buzz will be of >>> various frequencies, and it is difficult to tell them apart with just your >>> ears as detectors. >>> >>> Does it disappear if the microphone is not connected? Use XMIT to put the >>> K3 in transmit while you are listening. If it is only when the microphone >>> is connected, you may have a broken wire in the mic cable. >>> >>> 73, >>> Don W3FPR >>> >>> On 1/23/2012 10:10 AM, Hunsdon Cary III wrote: >>>> K3 Experts: My K3-100 has been flawless in its performance until >>>> yesterday. I had a schedule with W5ZNN who told me I had a hum on my >>>> signal; I put my headphones on and sure enough there it was on transmit. >>>> I tried plugging the Astron 35M directly into the AC outlet instead of the >>>> outlet strip - no luck, hum was still there. I connected the K3 to my SEC >>>> 1223 switching power supply and, you guessed it, the hum is still there. >>>> I hate to think there's something amiss with the K3 but it looks that way. >>>> Any ideas? >>>> 73, >>>> Cary, K4TM >>>> Lynchburg VAh >>>> [email protected] >>>> >>>> >>>> >>>> ______________________________________________________________ >>>> 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 >>>> >> >> H. Cary III >> [email protected] >> >> >> >> ______________________________________________________________ >> 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
