Date: Fri, 5 Nov 93 04:30:37 PST From: Ham-Homebrew Mailing List and Newsgroup Errors-To: Ham-Homebrew-Errors@UCSD.Edu Reply-To: Ham-Homebrew@UCSD.Edu Precedence: Bulk Subject: Ham-Homebrew Digest V93 #94 To: Ham-Homebrew Ham-Homebrew Digest Fri, 5 Nov 93 Volume 93 : Issue 94 Today's Topics: Homebrew kit source Rewinding Transformers (2 msgs) Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Homebrew Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: 3 Nov 1993 08:02:03 -0700 From: orca.es.com!cnn.sim.es.com!moons.sim.es.com!not-for-mail@uunet.uu.net Subject: Homebrew kit source To: ham-homebrew@ucsd.edu Of note about this kit source (JDR). The kits appear to be Ramsey kits. I know relatively little about the Ramsey kits. I f you do, please pass along your impressions. TNX -- Douglas L. Datwyler, WR7O Evans & Sutherland Computer Corp. preferred e-mail: datwyler@moons.sim.es.com ------------------------------ Date: 4 Nov 93 13:59:07 GMT From: ogicse!emory!europa.eng.gtefsd.com!howland.reston.ans.net!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!wvanhorn@network.ucsd.edu Subject: Rewinding Transformers To: ham-homebrew@ucsd.edu VK1RKF wrote: >process continues for about 50 layers. There are bolts in each of the >four corners, they are gone, but there is some really nasty glue substance >holding the layers together. Is there some easy way pulling out the >laminated sheets? Or should I just toss the old thing in the trash and >go buy a new one already wired for 12v? I rewound an old high-voltage transformer years ago. I don't think methods of construction have changed much since then, so for what it's worth, here is my suggestion. Laminations are stacked together with nothing but a little oxide between them, then the coils are assembled on and the whole thing is coated with varnish. So, I think you will find that the only thing holding the laminations together is the skin on the edge, rather like the latex on the top edge of a pad of paper. Once you get through that, the laminations will pull out easily. You might be able to get enough of it off with sandpaper to get it started, but probably varnish-remover would be better. Or, just sacrifice the top lamination on both sides and pry them off with a knife blade. Good luck, Van - W8UOF wvanhorn@magnus.acs.ohio-state.edu ------------------------------ Date: 4 Nov 93 20:50:25 GMT From: sdd.hp.com!col.hp.com!srgenprp!alanb@hplabs.hp.com Subject: Rewinding transformers To: ham-homebrew@ucsd.edu Michael Cowart (cowart@convex.com) wrote: : robert@garfield.csd.unbsj.ca (Robert Ford) writes: : >Hi, : >I am curious to know if anybody has successfully managed to rewind an old : >TV transformer for a different voltage. ... : I have found that the best way to separate the laminations is to "chisel" them : apart with a small screwdriver and small hammer. ... : When they transfomer is back together, soak the whole unit in varnish for : several hours. I always let it soak overnight, but at least allow all the air : bubbles to stop. Then, you bake it until the varnish is hard, hard, hard. Don't forget the re-varnishing step. If you don't do it, the transformer will still work but it will HHHHHHHHHUUUUUUUUUUUUUUUUMMMMMMMMMMMMMMMM! (The voice of experience!) I also recommend making sure the laminations are smooth and nick-free before reassembling. (Use a fine file or sandpaper.) AL N1AL ------------------------------ End of Ham-Homebrew Digest V93 #94 ****************************** ******************************