Conrad, Can you turn off the other devices around your rig to see if any of them are creating the problem? I had a small portable electric heater that created hum in my K3S when plugged into the same outlet. Running the heater on an extension cord to an outlet across the room fixed the problem.
Have you measured the AC ripple on the output of your DC power supply when you are key down? ____________ 73, Jim - N4ST -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Conrad PA5Y Sent: Friday, September 27, 2019 17:27 To: elecraft@mailman.qth.net Subject: [Elecraft] Audio Hum in TX Data Mode I put up a new 6m antenna mainly for EME and I was so looking forward to using my K3S. The RX is great, I run it in parallel with 2 other receivers and it works very well on EME. However try as I might I cannot get rid of some quite bad hum on the TX Audio. I am using USB and before you ask yes I have got a low impedance ground from the PC to the K3S although removing it makes absolutely no difference. What did make a difference was moving the radio away from sources of magnetic fields such as monitors. However I cannot get rid of it completely. It also increases or at least changes when I put my hands on the radio. I have a few other radios located nearby and close to a monitor, pc or PSU and they do not suffer from this at all. Is this a common problem, is it a bad ground in the audio path internally or magnetic coupling into an audio transformer? It is completely impractical for me to move my radios 10 feet from any magnetic fields. Short of wrapping the radio in mu metal I really do not seem to be able to fix this. Any ideas? I have read and understood and followed Jim K9YC's advice and this works perfectly for my other 3 radios. I am really at a loss. 73 Conrad PA5Y ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to hamsh...@n4st.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
