Date: Sat, 6 Nov 93 04:30:38 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 #95 To: Ham-Homebrew Ham-Homebrew Digest Sat, 6 Nov 93 Volume 93 : Issue 95 Today's Topics: Rewinding transformers 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: Fri, 5 Nov 93 22:11:54 GMT From: news.cerf.net!pagesat!ukma!gatech!news-feed-1.peachnet.edu!emory!europa.eng.gtefsd.com!howland.reston.ans.net!newsserver.jvnc.net!a3bee2.radnet.com!cyphyn!randy@network.ucsd.edu Subject: Rewinding transformers To: ham-homebrew@ucsd.edu I don't have the original post..so ... I've used a hammer and a wood-block to rap the laminations ( hard) and so loosen them enough to get one or two out using the chisel method. Then, using needle nose pliars, I got the rest out. However...BEFORE you take it apart, measure the volts and when you unwind the secondary (outside coil--with the low voltage), count the turns! Now..turns/volts= TPV New coil turns will be volts x TPV --- Another insulation one can use is paperbag paper..the brown stuff. Cut it into long enough strips, whose width is same as original coil form. Make more than you figure you might need! Varnish them 1st and when dry, lay one on/wrap around and tape it to hold it. Use tape to anchor your 1st turn and wind nice , neat layer of wire. Add more varnish as you wind new coil....one layer at a time...and as you start next layer, put on another paper..as above, on the coil you just did. Last turn should get some form of anchoring...I used string, sece wet-varnished paper won't allow tape. Put one more paper on over whole mess and let dry.` Assemble the lamination the same way you took em apart, examine them for gouges or kinks...repair and dab on varnish to any bare metal. Completed transformer should get soaked in varnish as a last step. Test your creation like this to avoid blowing fuses: o-------(uu)-------------o 117vac 100w your xformer input bulb primary o------------------------o If Xformer has a short, the bulb will light up full brite...rather than blow a house fuse. A good xformer will only cause bulb to glow dim or not at all. (try a smaller bulb if no light at all) -- Randy KA1UNW If you get a shock while servicing your equipment, "Works for me!" randy@192.153.4.200 DON'T JUMP! -Peter Keyes You might break an expensive tube! ------------------------------ Date: 6 Nov 93 07:19:32 GMT From: world!moroney@uunet.uu.net To: ham-homebrew@ucsd.edu References <2bb029INN93f@news.uwsuper.edu>, <1993Nov5.192134.17150@jupiter.sun.csd.unb.ca>, Subject : Re: Rewinding transformers The Radio Amateur's Handbook (at least older versions) give tips on rewinding power transformers. One thing they suggest is _not_ unwinding the primary winding when disassembling the transformer, and count the turns of the secondary to know the proper turns/volt. The primary is almost always on the inside (closest to the core). -Mike ------------------------------ End of Ham-Homebrew Digest V93 #95 ****************************** ******************************