Hi Don, Many thanks for your reply. I have read Jim's and your advice and counsel about RFI many times on this reflector and I am very grateful for your response tonight.
I will give your advice a try. I have some extra shield cable and can make the runs short between the equipment. For some context on why I went to a common point. I read, what I thought was an excellent article, about ground loops from the Flexradio site a couple of years ago. Here is the link: http://kc.flex-radio.com/knowledgebasearticle50426.aspx I thought that daisy chaining would introduce ground loops and hence the reason I went to a common point. However, I don't think you are advising this. Let me say it back to you: Follow the audio path first and then follow the coax path. For me, - Computer to the kx3 (using the computer's sound card for now) - Then bond the kx3 to the px3 - Then bond the kx3 to the KPA500 (I am borrowing this for FD) - then bond the KPA500 to my antenna tuner - Then bond the antenna tuner to the station ground point - Ground the power supply to the station ground. Again, thanks Don for the advice. I will let everyone know how I do after FD if my results change. regards, Brian VE3IBW On Thu, Jun 23, 2016 at 9:02 PM, Don Wilhelm <donw...@embarqmail.com> wrote: > Brian, > > The answer is *bonding* as described by Jim Brown K9YC for minimizing > noise, hum and buzz. > Connecting everything to a common point may actually make the situation > worse (see the K9YC papers). "Grounding" everything will not minimize > noise, hum and buzz. Mother earth ground is not a 'sink' for RF, noise, > hum or buzz - it is only for safety from AC mains faults or suppression of > surges coming in on your antenna feedline. > > Make your bonding follow the path(s) taken by the shields of your audio > cables and coax and you will have better results. > > In other words, bond the computer to the soundcard device (if included), > and bond that to the KX3. > Bond the KX3 to the PX3, and bond the antenna tuner to the KX3 (following > the path of the coax). > > Then you may bond the antenna tuner to your common ground point for AC > mains safety and lightning protection. > > The reasoning behind this bonding is to conduct much of the noise, hum and > buzz to the *outside* of the equipment enclosures rather than having it > conducted onto the ground plane of the PC boards. > > In the long past, we did not have those problems. Connectors were mounted > on the enclosure chassis, and any noise, hum or buzz would be conducted > onto the outside of the enclosure where it was not likely to cause any harm. > > With modern construction techniques, the connectors are mounted to the PC > board inside the enclosure (and not to the outside of the enclosure). That > means that any noise, hum and buzz that is picked up on the shields of AF > cables or coax will be conducted directly onto the ground plane of the > electronics. The bonding between enclosures in parallel to the audio and > RF paths drastically reduces the coupling of that noise, hum and buzz onto > the circuit board and lets it flow harmlessly onto the outside of the > enclosures. This is the "pin 1 problem" that K9YC refers to. > > If you do equipment to equipment bonding and bond the final element > (amplifier or antenna tuner) to your station ground, everything in the > station will also be grounded - assuming you use heavy wire or strap for > the equipment to equipment bonding - the shield stripped from old RG8 coax > will do nicely as will #12 or larger wire. > > Try it, it works. > > For those who ask how to bond to a laptop computer, my answer is "any way > you can" - if you have a jackscrew for a VGA connector, that is an obvious > point - otherwise connecting to the shell of a USB or HDMI connector may be > your only choice - do the best you can. > > 73, > Don W3FPR > > > On 6/23/2016 7:31 PM, Brian Waterworth wrote: > >> I disconnected the USB acc1 cable from the small computer I was planning >> to >> take with me to FD and the noise vanished. Each of the computer, the kx3, >> px3, external power supply, external antenna tuner are all grounded to a >> common point. The exception is the monitor and fan (it's going to be hot >> :-). >> >> >> > ______________________________________________________________ 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
