Jim, Excellent and comprehensive info on your website! Everyone should take a look at it.
In my setup, the power supplies for the KX3, Raspberry Pi and powered speakers are the typical 2-wire, no ground, switching supply in a plastic case, so ground potential is established through the audio interconnect. The rig and computer connect only through the USB ports for the USB serial adapter and the USB audio interface. After a little experimentation, I realized The “hum” I was hearing was RF getting into the powered speakers on transmit with the antenna I close proximity to the KX3. Moving the antenna away from the rig resolved the issue. This is a little off-topic, but may be of interest to the audio geeks on the list... I worked in TV engineering here in Nashville for many years, and we dealt with a lot of music recorded in big studios, and thus long cable runs and a lot of channels of audio. It was all analog in the early days and several audio engineering luminaries helped me immensely. One was Allen Burdick of Benchmark Media Systems. His “Clean Audio Installation Guide” is still indispensable: https://cdn.shopify.com/s/files/1/0321/7609/files/caig.pdf Deane Jensen of Jensen Transformers fame and his protégé, Bill Whitlock, were two others: https://www.jhbrandt.net/wp-content/uploads/2014/11/Design_of_High-Performance_Balanced_Audio_Interfaces.pdf And a local genius, Dave Harrison, who designed an built the legendary Harrison Consoles that we used extensively: https://harrisonconsoles.com/site/history.html 73, Mike, W8NWA ________________________________ From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> on behalf of Jim Brown <j...@audiosystemsgroup.com> Sent: Thursday, August 8, 2019 2:35 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KX3 and JS8CALL On 8/7/2019 11:02 AM, Michael Arnold wrote: > This method may result in some low-level 60 and 120 Hz audible ground loop > hum when AC powered, particularly with the powered speaker connected, Power line hum and buzz can be prevented by 1) getting power for all interconnected equipment from the same AC outlet, or from outlets whose Green Wires are bonded together, AND 2) bonding from chassis to chassis of all interconnected equipment, AND 3) proper bonding of all grounds in the home, including ground from that interconnected equipment in the shack. All three are necessary. There's a tutorial on this at k9yc.com/publish.htm 73, Jim K9YC ______________________________________________________________ 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
