I never assumed that Astron assumed their linear supplies were in metal enclosures for the purpose of shielding. They are, after all, linear supplies that would not normally require shielding.
I'm not familiar with their switchers. Does bonding he case together reduce the RFI they create? It was my impression that they designed them to be clean as supplied. 73, Ron AC7AC -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob McGraw - K4TAX Sent: Thursday, October 29, 2015 4:50 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Which of these would make the best power supply for the K3(S)? It is amazing how many times I've found this to exist and how many times that I've written about this on various reflectors. The power coat paint on the chassis makes for an excellent insulator. If you have an Astron power supply and you have not checked to see that third pin ground is electrically connected to the chassis, or you have not checked to see that he outer shell is connected to the bottom shell, both being insulated by paint..........shame on you. This applies to all Aston supplies, both linear and switching. Remove the cover, remove the ground terminal where the green wire is attached, scrape away the paint, place an internal tooth lock washer between the terminal and chassis and reinstall the screw and nut. As to the shell, using 100# sandpaper, sand away the paint on the inside for an area about the size of a dime on both pieces, being the shell and pan, where the screws attach same. 73 Bob, K4TAX On 10/29/2015 4:25 PM, Jim Brown wrote: > On Thu,10/29/2015 2:13 PM, Fred Jensen wrote: >> The intermittent problem turned out to be paint under a lug with a >> loose screw. > > That seems to be a very common problem with Astrons -- the power > system "green wire" (safety ground) is soldered to the mounting lug of > a terminal strip, which is insulated from the chassis by paint. This > is a MAJOR violation of NEC. To make matters worse, the V- terminal is > soldered to the same lug. The combination makes the unit susceptible > to RFI. > > In one of my Astrons, the two sections of the chassis are insulated > from each other by paint, so the unit is essentially unshielded as well. > > I do NOT recommend bonding V- to the chassis, so when you're fixing > the paint problems, cut that jumper. There's no good reason for it. > > 73, Jim K9YC ______________________________________________________________ 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 r...@elecraft.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
