Exactly why I sold mine. It is noisey and basically worthless to me. Perhaps the newer ones work better. I am using other more recent switching supplies that don't give me any issues and they are a whole lot less expensive.
73, Bill K9YEQ -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob Sent: Monday, January 11, 2010 6:30 PM To: elecraft@mailman.qth.net Subject: [Elecraft] How to Eliminate Power Supply Birdies? I have an Alinco DM-330MVT power supply that has significant birdies on 160M. The power supply has a nice feature that allows you to move the birdies, which makes it obvious that the birdies are originating from the power supply. The birdies are at least 1 S-unit above the background noise. Here's what I've done to try to eliminate them: - added a filter connected to the DC output consisting of 4 toroid beads (type 77) in series on each side and 0.1 caps across the leads and from each lead to ground. I also have both leads going about 10 turns through a type 77 toroid to filter common mode birdies. - I've put 2 snap on type toroids on the AC line as well as wound the ac cord through a T200-1 toroid (which I had lying around) . - I shielded all of the power leads from the power supply to all of the equipment that it powers (mostly my K2, KAT100 and external speaker/amp), with the shields connected to both the power supply and the K2 chassis grounds. - I've moved the power supply away from my K2 (about 5' away). All of this seems to have absolutely no affect on the birdies. To add to the mystery, the birdies are there only when I have an antenna connected to the K2, so it would appear that the Power supply is radiating, but with all of the wires to it filtered and the DC lines shielded, where can it be radiating from - (as a test I put the whole power supply inside a metal file box and grounded that to no effect. So, can anyone explain this? Other than buying a new power supply, what do I do now? Except for the birdies on 160M, this is a nice power supply that's small enough to fit into an attaché case with my K2, KAT100, mic and key. Thanks. Bob W1SRB ______________________________________________________________ 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 ______________________________________________________________ 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
