Regarding drying transformers etc. I have been drying transformers and chokes for quite a few years. I have used both electric and gas ovens with no apparent difference in results. I store my spare transformers in an unheated outbuilding and temperatures here in Wisconsin run from -20F to +100 so condensation can be a problem in many different devices. I first check the resistance from winding to core with a small hand held megger which applies about 1000 volts. I find many transformers and chokes will have an indication of leakage to ground after a year or so in storage. After baking for 4 hours or so at 200+ degrees and allowing to cool, the megger will indicate infinite resistance winding to core. I have found a something strange, to wit, if the measurement is taken soon after removal from the oven , the megger will still indicate a leakage resistance. Upon cooling the resistance will usually be infinite. The transformers with tar type potting seem to be the worst offenders at absorbing moisture. I assume this is due to cracking of the tar. John K9XH
Donald Chester wrote: > > Be careful about using a gas-fired oven to dry out the transformers. Water > is a by-product of gas combustion, and the air will carry plenty of water > vapour. Better to use an electric stove oven. > > If you are in no hurry, bring the transformer into a dry, heated room and > store it there over the winter season. By the time you start cutting off > the heat in the spring, the transformer should be well dried out. It is > more effective to let the moisture gradually evaporate from the guts of the > transformer, just as it gradually condensed there when the transformer was > in a moist environment, and there will be less likelihood of abnormally hot > temperature causing deterioration of the insulation. > > Don K4KYV > > _________________________________________________________________ > Add photos to your messages with MSN 8. Get 2 months FREE*. > http://join.msn.com/?page=features/featuredemail > > _______________________________________________ > AMRadio mailing list > [email protected] > http://mailman.qth.net/mailman/listinfo/amradio
