> Wonder what supplies are being used with the K3? Merv,
For the shack, I gave up on switch-mode power supplies since I could not find one that produced a low noise floor on all bands. For years, I was unknowingly putting up with a high-level noise floor until I purchased the SDR-IQ and began seeing broad "bumps" in the viewed spectra response. The bumps were attributed to switch mode power supplies, switch-mode wall supplies, and some USB adapters. By changing switch-mode back to old linear technology and a combination of changing the USB adapters as well as using multi-wound #31 ferrite cores (wound K9YC style) on both ends of the USB cables, I finally have a flat noise floor on all bands. I am sure there are quiet switch-mode supplies out there. But with all the other noise sources I have to contend with, I don't want to be asking myself if some new grunge I'm hearing in the future is attributed to my power supply. My guess is that many of us are living with high noise floors from switch-mode products and do not realize it -- until a PAN adapter is added and the noise floor can be seen. Spotting sharp switch-mode and LAN-type grunge is easy without a PAN adapter, but it's the very broad noise (e.g., gentle rise and fall over 100 kHz) that's deceptive when one tunes the band. The shack supply here is now a surplus linear Agilent 6652A. These sell new in the $4K range but are only a few hundred $$ if you catch the right on-line sales for surplus product. Paul, W9AC ______________________________________________________________ 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
