I took the easy way out. A used notepad provided the cardboard which was folded and wedged under the top cover. Problem solved.
Rick WA6NHC Smell Czech correction happens > On Jun 9, 2019, at 3:24 PM, inventor61 . <invento...@gmail.com> wrote: > > Hank > > I am only fabricating new top covers for the 35A size Astron units. > > For the majority of acoustic noise situations in the 35 amp size units (the > variable and the fixed voltage models) the height of the steel cabinet is > insufficient to keep the sheet metal of the lid away from the flux lines of > the transformer. > > The resulting eddy currents decay and 'fight' against the transformer field > itself. > This results in the buzzing type hum people experience. > > Over time this vibration can loosen the transformer windings so it can buzz > by itself. > But generally, the bulk of the objectionable acoustic noise is from the top > cover.. > > You can confirm the cause by simply removing the cover and operating the > supply. > There are only seven screws, as you probably already know. > > Suitable electrical safety precautions are to be taken, of course. > > If you have a 35A Astron unit and by the above method you can show yourself > that the buzzing/hum noise is a result of the magnetic coupling / > circulating current scenario I have described, this new composite cover > will solve the problem - as well as reducing the obvious waste heat from > the supply. > > Steve KZ1X > >> On Sun, Jun 9, 2019 at 6:17 PM HB <h...@optilink.us> wrote: >> >> Some more of the factory cork pieces between the transformer and case >> fixed mine up – the 50 also. >> >> >> >> Hank >> >> K4HYJ >> >> >> >> *From: *inventor61 . <invento...@gmail.com> >> *Sent: *Sunday, June 9, 2019 1:48 PM >> *To: *li...@w2irt.net; elecraft@mailman.qth.net >> *Subject: *[Elecraft] [OT] RS-35M noise >> >> >> >> Peter >> >> >> >> I now have the prototypes completed of a composite material cover to >> >> replace Astron 35A size power supply covers. >> >> >> >> This solves the acoustic noise problem. >> >> >> >> The new cover looks terrific and is a 1:1 swap with the old one. >> >> >> >> I went through *exactly* the same problem you describe, and then buying the >> >> same replacement supply, then modifying it, ad nauseum, before fixing the >> >> original issue. >> >> >> >> I expect to be able to produce these (it's done on a CNC machine) in the >> >> coming weeks. >> >> I have several requests already. >> >> >> >> I do not yet know the cost but it won't be outrageous. >> >> Would this interest you? It has certainly interested others! >> >> >> >> 73 Steve KZ1X >> >> ______________________________________________________________ >> >> 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 h...@optilink.us >> >> >> > ______________________________________________________________ > 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 wa6...@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
