John - I have known some supplies to do this with the initial current inrush. A problem reported by some is "singing" of the transformer, usually due to loose laminations or transformer not tightened to case.
I have never been fond of the Pyramid power supplies. My experience is that Pyramid achieved lower retail costs than Astron and other suppliers by "cutting corners" with the heat sink size (thermal mass) and filter capacitor ratings. The eHam.net product reviews appear to support my observations and experience http://www.eham.net/reviews/detail/974 http://www.eham.net/reviews/detail/960 As Dave Metz points out (and the reviews) some these short comings can be addressed by replacing key components with better values and ratings. http://www.seits.org/features/pwrsup.htm w9gb > Message: 3 > Date: Thu, 16 Dec 2004 17:31:49 GMT > From: WT5Y > Subject: [Elecraft] OT power supply question > To: Elecraft mailing list > > I use a Pyramid power supply. PS35G to be exact. Sometimes when I turn it > on it makes a > thudding sound. But it works fine and it doesn't do it all the time. I am > not the original owner > and I've had it for a couple years so I know its getting pretty old by now. > Wondering what would > make that noise. Kinda sounds like someone hit a metal box with a mallet > best I can describe > it. > > WT5Y > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
