Hello, inmates! not all mics on the Yamaha CM-500 headsets are electret, I tested mine before making the connectors; I am not using it w/my KX3, using w/Kenwood TS-480 and Yaesu FT-897. Cheers, Jose Douglas KB1TCD
Stay Free everyone! Sent from my iPad > On May 10, 2020, at 5:24 PM, Jim Brown <[email protected]> wrote: > >> On 5/10/2020 12:05 PM, Frank O'Donnell wrote: >> For my CM500 headset with the KX3, I referred to Walter Underwood K6WRU's >> blog posts to order the adapter allowing the CM500 mic plug and a PTT switch >> to share the radio's mic jack. I also followed his checklist from a second >> blog post to set TX EQ and mic bias. >> While adjusting the mic gain with the TX power set to 0.0, I noticed hum on >> my audio from the CM500 mic. This was audible regardless of whether I had >> the PTT cable attached, or if I left it detached and tapped the XMIT button. >> The hum also appeared regardless of whether I used the CM500 phones vs other >> headphones. If I unplug the adapter and use the handheld mic that came with >> the KX3, the hum does *not* appear. >> Any suggestions on what I should look at to run this down? > > 1) Is what you hear HUM (pure 60 Hz) or BUZZ (harmonics of 60 Hz)? In > general, most hum is magnetically coupled, while buzz is power line leakage > currents, aggravated by by Pin One Problems and failure to do proper bonding. > > 2) Make sure that the adapters you got are actually doing what you think they > are doing (or that you want them to do), checkin them out with an Ohmmeter. > > 3) Make sure that bias is turned on -- the mic in CM500s is an electret, > which requires bias. > > 4) Make sure that Mic Gain and Comp are not turned up too high. To set them, > turn Comp all the way down, set TXEQ (see next step), then set Mic Gain to > get indicated 100% modulation on the meter. > > 5) For TXEQ, set three lowest bands (50, 100, 200 Hz) for max cut, set next > band (400 Hz) for 6dB cut), set the top two bands for about 6dB boost. > > 6) Make sure that everything in your station that connects to AC power, > including any computer CONNECTED to your radio and anything connected to the > computer, has their chassis bonded together AND powered from the same outlet, > or from outlets whose green wires are bonded together, and one of those > chassis connections bonded to your station ground , AND all grounds in your > home all bonded together. These slides have drawings that illustrate > conceptually how to do it right. > > http://k9yc.com/GroundingAndAudio.pdf > > 73, Jim K9YC > ______________________________________________________________ > 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 > Message delivered to [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 Message delivered to [email protected]
