Thanks for address this thread Howard! 73
On Mon, Nov 20, 2017 at 1:35 AM, Howard Hoyt <hh...@mebtel.net> wrote: > Hi Stan, > > One thing we have learned in supplying thousands of Kx33s to hams is the > importance of minimizing or eliminating common-mode currents in the antenna > system. The transverse mode RFI output of the Kx33 is extremely low and has > never been the cause of noise to our customers, but if the antenna system > has significant common-mode potential, it will always seek a current path > through whatever is attached to the rig...through the power supply, your > body, as well as grounds. The outside of the coax shield, the rig, the > power supply and AC mains are all in a series path for common-mode currents. > > The most direct cure is to place a high common-mode impedance in the antenna > feedline. The DC power lead on the Kx33 is smaller in diameter than most RF > coax lines, so it may be easier to form a choke on that cable. You > mentioned "YES, I HAD CHOKES ON ALL SUPPLIES, CABLES, WIRE." The exact core > material used and number of turns is important in constructing common-mode > chokes. Jim Brown, K9YC has excellent tutorials on this subject: > http://audiosystemsgroup.com/RFI-Ham.pdf > > Another measure which will shunt common mode currents away from other paths > is a low impedance ground on the rig. > > Something else I want to mention, as it is an issue which has cropped up > recently: There are several sellers on both eBay and Amazon stating "Pro > Audio Engineering Kx33 power supply" in their ads, but no supplies other > than those sold directly from us are the actual Kx33. We know this because > we worked with one such customer to resolve noise issues and it turned out > the unit he had was not a Kx33. eBay and Amazon both state they can not do > anything, since the other vendors are claiming they use our part number and > name only to state an equivalency, which they most assuredly are not. Our > Kx33 has less than 70 pF of input to output coupling vs. 1000 pF or more for > most other supplies, making it far easier to choke common-mode currents. > This was the most difficult spec of the supply to arrive at, but considering > we knew it could be used with temporary antenna systems with common-mode > potential it was important to achieve. > > As we unconditionally guarantee everything we sell, please contact us at > i...@proaudioeng.com and I am sure we can help you eliminate this noise or > refund your purchase price. > > Cheers & 73, > > Howard Hoyt - WA4PSC > www.proaudioeng.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 jt.to...@gmail.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
