Noise can absolutely change with load. At light load the SMPS may enter a pulse skipping mode. Some keep pulse width constant and vary switching frequency with load to effectively change duty cycle. Most (all?) will continuously modulate the switching frequency over a small range to spread out the pulse energy. This makes it much easier to come in under required limits, but also by the time you're looking at harmonics up in our bands it's a big smudge of noise.
73, Josh W6XU Sent from my mobile device > On Nov 20, 2017, at 12:58 PM, Doug Smith <d...@w7kf.com> wrote: > > I have often wondered if the noise from a switching power supply would vary > in intensity or other characteristics as the load changes. For example, > during transmitting. In a single transmitter environment the user would > probably not notice but in a multi-transmitter or SO2R station one just > might. > > Changes in noise floor might not always be “phase noise” from the other > transmitter — could it be different emissions from a switching power supply > under full load? > > 73, > Doug, W7KF > http://www.w7kf.com <http://www.w7kf.com/> > > >> On Nov 19, 2017, at 6:42 PM, stan levandowski <sjl...@optonline.net> wrote: >> >> Yeah, me too. I bought it because I thought it would be "super clean" and >> really small. But its contribution to my problem was pretty much >> unarguable: Plug it in and I hear noise. Unplug it and I don't hear noise. >> The instructions that came with it specifically stated that the Kx33 should >> be placed the full length of the DC plug/cord away from the transceiver. I >> did that but it didn't work for me. I tried different outlets around the >> house too. I put chokes on it. No joy. >> ______________________________________________________________ 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
