RE: [AMRadio] Re: 500 Transformer
I think most of mine just floated away. They may some day, wash to shore in Southern California or Florida and become useful there. HIHI -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donald Chester Sent: Thursday, February 13, 2003 8:11 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] Re: 500 Transformer Never throw away a tube that has not been tested, no matter how rough a shape it appears to be in. Some of my best 211's (my HF-300 rig uses a 211 rf driver) came out of that pile of mined tubes. Don K4KYV _ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Re: 500 Transformer
From: Geoff Edmonson <[EMAIL PROTECTED]> ...This doesn't mention that the whole rig was under water, and that the 250TH's survived (if I recall correctly [IIRC]) without damage. Reminds me of the time W9WT Bob Parmentier's XYL called Roger N4IBF (SK) and me to come get all his radio stuff after he had moved into a nursing home, or she was going to get someone to haul it to the dump. After we had crammed a medium size U-haul truck full, I found some tubes in an old house on the property. The floor had rotted through years earlier, and termites had finished off the wood. There was a large collection of unused transmitting tubes (mostly 211/VT-4C's) that had literally buried themselves in the ground, as the cardboard cartons rotted away. We literally mined tubes out of the ground, using an old concrete trowel we happened to find at the site. Some of them were buried as much as 6-inches below the surface. I brought the tubes home. First, I washed them to remove the mud residue. Then used steel wool to remove the oxide from the tube pins and metal base. There was some pitting of the base, but the pins were intact once cleaned. I tried those tubes in my transmitter and out of a dozen or so only one or two tubes were bad. Those tubes had to have been buried for a couple of decades for the remains of the floor and termite residue to have completely converted to dirt and caused the tubes to be buried. Never throw away a tube that has not been tested, no matter how rough a shape it appears to be in. Some of my best 211's (my HF-300 rig uses a 211 rf driver) came out of that pile of mined tubes. Don K4KYV _ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus
Re: [AMRadio] Re: 500 Transformer
I have an old stove in the basement- used to be used for canning etc. the oven is never used for cooking food here, so- perfect for baking transformers and paint hi. Russ. I have never had any problem using an oven for baking stuff like that. Just try to avoid spilling tar or oil directly into the oven. Use a drip pan under the device being baked to catch any possible spills. When you are finished, there may be some odour, but it almost always goes away when the oven cools. If there are any lingering traces, run the oven at maximum heat for about 20 minutes and that will take care of anything left. I have never had the XYL complain after I finished cooking a transformer, as long as I don't do it while she is in te middle of preparing a meal. She griped the first couple of times, but now that she has seen for herself that it doesn't leave any permanent residue in the oven, she doesn't care anymore. Don _ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail
Re: [AMRadio] Re: 500 Transformer
Hi Russ, You're a lucky guy! But you've STILL gotta watch it when baking paint---the odours are something else... ~73~ Eddy VE3CUI - VE3XZ > I have an old stove in the basement- used to be used for canning > etc. the oven is never used for cooking food here, so- perfect for > baking transformers and paint hi. Russ. > > > > > > >>From: "Eddy Swynar" <[EMAIL PROTECTED]> >>Reply-To: amradio@mailman.qth.net >>To: >>Subject: Re: [AMRadio] Re: 500 Transformer >>Date: Wed, 12 Feb 2003 21:31:23 -0500 >> >>Jeff, >> >>Baking transformers behind the XYL's back is a CINCH---the REAL >>challenge comes when you're trying to bake on an enamel finish paint >>job on some enclosure that you sprayed earlier...! >> >>Even I must admit to doing such things REALLY early in the morning >>(when she's asleep), or when she's out on some errand! >> >>~73~ Eddy VE3CUI - VE3XZ >> >> >> >> >> >> >>- Original Message - >>From: "Jeffrey J. May" <[EMAIL PROTECTED]> >>To: >>Sent: Wednesday, February 12, 2003 7:17 PM >>Subject: Re: [AMRadio] Re: 500 Transformer >> >> >> > Hi John! >> > You mean that your wonderful xyl lets you use her oven! 68F here >> > today!..73..Jeff..W0XV >> > - Original Message - >> > From: "John Leer" <[EMAIL PROTECTED]> >> > To: >> > Sent: Wednesday, February 12, 2003 6:24 PM >> > Subject: Re: [AMRadio] Re: 500 Transformer >> > >> > >> > > 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 >> > > > AMRadio@mailman.qth.net >> > > > http://mailman.qth.net/mailman/listinfo/amradio >> > > >> > > ___ >> > > AMRadio mailing list >> > > AMRadio@mailman.qth.net >> > > http://mailman.qth.net/mailman/listinfo/amradio >> > > >> > >> > >> > ___ >> > AMRadio mailing list >> > AMRadio@mailman.qth.net >> > http://mailman.qth.net/mailman/listinfo/amradio >> >>___ >>AMRadio mailing list >>AMRadio@mailman.qth.net >>http://mailman.qth.net/mailman/listinfo/amradio > > > _ > Help STOP SPAM with the new MSN 8 and get 2 months FREE* > http://join.msn.com/?page=features/junkmail > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Re: 500 Transformer
I have an old stove in the basement- used to be used for canning etc. the oven is never used for cooking food here, so- perfect for baking transformers and paint hi. Russ. From: "Eddy Swynar" <[EMAIL PROTECTED]> Reply-To: amradio@mailman.qth.net To: Subject: Re: [AMRadio] Re: 500 Transformer Date: Wed, 12 Feb 2003 21:31:23 -0500 Jeff, Baking transformers behind the XYL's back is a CINCH---the REAL challenge comes when you're trying to bake on an enamel finish paint job on some enclosure that you sprayed earlier...! Even I must admit to doing such things REALLY early in the morning (when she's asleep), or when she's out on some errand! ~73~ Eddy VE3CUI - VE3XZ - Original Message - From: "Jeffrey J. May" <[EMAIL PROTECTED]> To: Sent: Wednesday, February 12, 2003 7:17 PM Subject: Re: [AMRadio] Re: 500 Transformer > Hi John! > You mean that your wonderful xyl lets you use her oven! 68F here > today!..73..Jeff..W0XV > - Original Message - > From: "John Leer" <[EMAIL PROTECTED]> > To: > Sent: Wednesday, February 12, 2003 6:24 PM > Subject: Re: [AMRadio] Re: 500 Transformer > > > > 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 > > > AMRadio@mailman.qth.net > > > http://mailman.qth.net/mailman/listinfo/amradio > > > > ___ > > AMRadio mailing list > > AMRadio@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/amradio > > > > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio _ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail
Re: [AMRadio] Re: 500 Transformer
John E. Coleman wrote: Here is a story that I'm sure some of you have heard but others may enjoy. In 1994 a flood came to the Spring, Texas area, just north of Houston, and water was over the top of the building that our business was in. In addition, the ham shack was a trailer that was near the business building and it washed away and busted up under the bridge of IH45 at Spring Creek. The water didn't go down for several days. Then there was the clean up and go hunting time. I'll try to keep this short. [...] After a couple of hours with the rope and truck we had the thing out of the hole. Sure enough it looked pretty wrecked and worthless. But I dragged it up and threw it aside for a while. Packed full of mud, the ants made a home in it. About another 6-8 months I decided to wash it out. I had now decided that I would rebuild. Two 813 sockets had to be replaced the modulation XFMR measured 2 k ohms from anywhere to anywhere. So I said to my self that I would just rewind it. I took it all apart and started cleaning in preparation for making measurements and turn counts. After knocking it all down to the core and iron I put it up on a shelf for a while. The storage place would reach 150 deg during the summer. When I got back to the job at hand (about another 6 - 8 months), I found that all the shorts had disappeared. I reassembled the MOD - XFMR and gently started putting audio to it. Well it is in use today with 4 - 813s running 2500 volts as modulators and pouring audio to a pair of 250ths @ 1600 - 2000 volts (depending on the draw bridge position). I would have never believed it if it weren't my own. BTW all the other XFMRS on the chassis are still doing there thing. This doesn't mention that the whole rig was under water, and that the 250TH's survived (if I recall correctly [IIRC]) without damage. -- Regards, -Geoff
Re: [AMRadio] Re: 500 Transformer
Jeff, Baking transformers behind the XYL's back is a CINCH---the REAL challenge comes when you're trying to bake on an enamel finish paint job on some enclosure that you sprayed earlier...! Even I must admit to doing such things REALLY early in the morning (when she's asleep), or when she's out on some errand! ~73~ Eddy VE3CUI - VE3XZ - Original Message - From: "Jeffrey J. May" <[EMAIL PROTECTED]> To: Sent: Wednesday, February 12, 2003 7:17 PM Subject: Re: [AMRadio] Re: 500 Transformer > Hi John! > You mean that your wonderful xyl lets you use her oven! 68F here > today!..73..Jeff..W0XV > - Original Message - > From: "John Leer" <[EMAIL PROTECTED]> > To: > Sent: Wednesday, February 12, 2003 6:24 PM > Subject: Re: [AMRadio] Re: 500 Transformer > > > > 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 > > > AMRadio@mailman.qth.net > > > http://mailman.qth.net/mailman/listinfo/amradio > > > > ___ > > AMRadio mailing list > > AMRadio@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/amradio > > > > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Re: 500 Transformer
Hi John! You mean that your wonderful xyl lets you use her oven! 68F here today!..73..Jeff..W0XV - Original Message - From: "John Leer" <[EMAIL PROTECTED]> To: Sent: Wednesday, February 12, 2003 6:24 PM Subject: Re: [AMRadio] Re: 500 Transformer > 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 > > AMRadio@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/amradio > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio >
Re: [AMRadio] Re: 500 Transformer
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 > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
RE: [AMRadio] Re: 500 Transformer
Here is a story that I'm sure some of you have heard but others may enjoy. In 1994 a flood came to the Spring, Texas area, just north of Houston, and water was over the top of the building that our business was in. In addition, the ham shack was a trailer that was near the business building and it washed away and busted up under the bridge of IH45 at Spring Creek. The water didn't go down for several days. Then there was the clean up and go hunting time. I'll try to keep this short. Most of the pieces were found but the modulation deck which had 4 813s, the filament-XFRM, Screen supply XFMR, Modulation XFRM, and Driver XFMR was missing. There was a tremendous hole that had formed around one of the bridge support pillars under the bridge. I assumed it was in that hole. About 6-8 months later as I was driving under the bridge I noticed that there was a corner of something sticking out of the mud. I took a closer look and it was the corner of a metal military desk. As I pondered it I saw something else, it was a corner of the modulator chassis. After a couple of hours with the rope and truck we had the thing out of the hole. Sure enough it looked pretty wrecked and worthless. But I dragged it up and threw it aside for a while. Packed full of mud, the ants made a home in it. About another 6-8 months I decided to wash it out. I had now decided that I would rebuild. Two 813 sockets had to be replaced the modulation XFMR measured 2 k ohms from anywhere to anywhere. So I said to my self that I would just rewind it. I took it all apart and started cleaning in preparation for making measurements and turn counts. After knocking it all down to the core and iron I put it up on a shelf for a while. The storage place would reach 150 deg during the summer. When I got back to the job at hand (about another 6 - 8 months), I found that all the shorts had disappeared. I reassembled the MOD - XFMR and gently started putting audio to it. Well it is in use today with 4 - 813s running 2500 volts as modulators and pouring audio to a pair of 250ths @ 1600 - 2000 volts (depending on the draw bridge position). I would have never believed it if it weren't my own. BTW all the other XFMRS on the chassis are still doing there thing. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, February 11, 2003 7:52 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] Re: 500 Transformer I'll second the slow-dry method. The dessicant capsule in my Collins PTO turned from pink to blue in just a few days just from sitting in my heated basement room, 29% relative humidity! -Tony, K1KP ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Re: 500 Transformer
I'll second the slow-dry method. The dessicant capsule in my Collins PTO turned from pink to blue in just a few days just from sitting in my heated basement room, 29% relative humidity! -Tony, K1KP
Re: [AMRadio] Re: 500 Transformer
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
Re: [AMRadio] Re: 500 Transformer
Hi Russ, You speak the truth... I still have an old Speedy Memo somewhere in my shack library from one of the Hammond Transformer engineers in Guelph, Ontario, Canada, advising me to literally BAKE any long-unused, vintage, unpotted transformers in the oven, to remove residual accumulated moisture BEFORE using them! (or pay the consequences, Hi Hi). If memory serves me well, I believe they should be "cooked" upside down, at about 200 F, for a couple of hours... It certainly makes sense to me. What I do here to the "end bell" types with "open" bottoms is pump the insides up clear level with the bottom of the bells with clear silicone sealant after they've dried. I smooth the sealant flat at the bottom, so the thing will rest properly on the chassis. I figure this extra bit of work "seals" the windings, and discorages any undo tendency to vibrate, as well... I've done this to about 4 transformers, or so, & have yet to experience any failure (TOUCH WOOD, Hi Hi). ~73~ Eddy VE3CUI - VE3XZ> It is not really unusual for these transformers to go bad. You > must consider the age and how they were manufactured. You can > blame Johnson for using cheaper transformers, they could have > used potted designs. But who would have thought that you would > be using this old stuff? Old transformers do bad things- they > suck up moisture in the air and the windings viberate and break > down the > insulation. I don't think you will find anything seriously wrong > with your amp.Heres an experiment: got an old unsealed > transformer in the basement that has not been run in a few years? > Put it in the oven@ 200 degrees. Just leave it in for a few > minutes.Open the oven door and you are likely to see it > steaming! > Thats water.Russ. > > > > > > >>From: Dave Aabye <[EMAIL PROTECTED]> >>Reply-To: amradio@mailman.qth.net >>To: amradio@mailman.qth.net >>Subject: [AMRadio] Re: 500 Transformer >>Date: Mon, 10 Feb 2003 14:20:22 -0500 >> >>Hi Gary, >> >>Yep, it's a bummer! >> >>WZ1M wants $260 to rewind the existing transformer. Peter Dahl sells a >> replacement >>for $285. I think that Dahl offers a better deal because it is a >>hypersil unit >>with a 500 ma CCS rating. I believe the original is rated 400 ma ICAS. >> Only >>drawback is the need for 4 new mounting holes. >> >>I replaced the tube recitifiers with solid state units shortly after >>purchasing the >>500 (about two years ago). I also inserted thyristers in the primary >>leads to cut >>down on inrush current. I wonder if you have any further protective >>measures to >>suggest. >> >>73 de Dave, W4QCU >>Oak Ridge, TN >> >>Gary Blau wrote: >> >> > Dave: >> > >> > Ouch. Sorry to hear that. >> > Sounds like WZ1M's offer to rewind might be attractive, unless you >> > can find another 500 xfmr somewhere (good luck!). That's a great >> > rig so it's worth the investment. >> > >> > Now, to find out why it went bad in the first place... >> > Best of luck. >> > >> > Gary >> > W3AM >> > >> > Dave Aabye wrote: >> > > >> > > Hello Gary, >> > > >> > > Thanks for the suggestion, which I believe has proven to be >>conclusive. >> > > >> > > I hooked my Variac to the primary and slowly increased the >> > > secondary >>voltage. >> > > The caps were disconnect from the rectifiers, so the transformer >> > > was >>"all by >> > > itself". At about 700 volts, the voltage started to jump just a >> > > bit. >>At >> > > maybe 750 v, the secondary emitted a puff of smoke with an >>accompanying hiss. >> > > >> > > I think it is clear that the transformer is shot. Time to call >> > > Peter >>Dahl! >> > > >> > > Again, thanks for your input. >> > > >> > > 73 de Dave >> > >> > ___ >> > AMRadio mailing list >> > AMRadio@mailman.qth.net >> > http://mailman.qth.net/mailman/listinfo/amradio >> >>___ >>AMRadio mailing list >>AMRadio@mailman.qth.net >>http://mailman.qth.net/mailman/listinfo/amradio > > > _ > STOP MORE SPAM with the new MSN 8 and get 2 months FREE* > http://join.msn.com/?page=features/junkmail > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
Re: [AMRadio] Re: 500 Transformer
It is not really unusual for these transformers to go bad. You must consider the age and how they were manufactured. You can blame Johnson for using cheaper transformers, they could have used potted designs. But who would have thought that you would be using this old stuff? Old transformers do bad things- they suck up moisture in the air and the windings viberate and break down the insulation. I don't think you will find anything seriously wrong with your amp.Heres an experiment: got an old unsealed transformer in the basement that has not been run in a few years? Put it in the oven@ 200 degrees. Just leave it in for a few minutes. Open the oven door and you are likely to see it steaming! Thats water.Russ. From: Dave Aabye <[EMAIL PROTECTED]> Reply-To: amradio@mailman.qth.net To: amradio@mailman.qth.net Subject: [AMRadio] Re: 500 Transformer Date: Mon, 10 Feb 2003 14:20:22 -0500 Hi Gary, Yep, it's a bummer! WZ1M wants $260 to rewind the existing transformer. Peter Dahl sells a replacement for $285. I think that Dahl offers a better deal because it is a hypersil unit with a 500 ma CCS rating. I believe the original is rated 400 ma ICAS. Only drawback is the need for 4 new mounting holes. I replaced the tube recitifiers with solid state units shortly after purchasing the 500 (about two years ago). I also inserted thyristers in the primary leads to cut down on inrush current. I wonder if you have any further protective measures to suggest. 73 de Dave, W4QCU Oak Ridge, TN Gary Blau wrote: > Dave: > > Ouch. Sorry to hear that. > Sounds like WZ1M's offer to rewind might be attractive, unless you can > find another 500 xfmr somewhere (good luck!). That's a great rig so > it's worth the investment. > > Now, to find out why it went bad in the first place... > Best of luck. > > Gary > W3AM > > Dave Aabye wrote: > > > > Hello Gary, > > > > Thanks for the suggestion, which I believe has proven to be conclusive. > > > > I hooked my Variac to the primary and slowly increased the secondary voltage. > > The caps were disconnect from the rectifiers, so the transformer was "all by > > itself". At about 700 volts, the voltage started to jump just a bit. At > > maybe 750 v, the secondary emitted a puff of smoke with an accompanying hiss. > > > > I think it is clear that the transformer is shot. Time to call Peter Dahl! > > > > Again, thanks for your input. > > > > 73 de Dave > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio _ STOP MORE SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail
[AMRadio] Re: 500 Transformer
Hi Gary, Yep, it's a bummer! WZ1M wants $260 to rewind the existing transformer. Peter Dahl sells a replacement for $285. I think that Dahl offers a better deal because it is a hypersil unit with a 500 ma CCS rating. I believe the original is rated 400 ma ICAS. Only drawback is the need for 4 new mounting holes. I replaced the tube recitifiers with solid state units shortly after purchasing the 500 (about two years ago). I also inserted thyristers in the primary leads to cut down on inrush current. I wonder if you have any further protective measures to suggest. 73 de Dave, W4QCU Oak Ridge, TN Gary Blau wrote: > Dave: > > Ouch. Sorry to hear that. > Sounds like WZ1M's offer to rewind might be attractive, unless you can > find another 500 xfmr somewhere (good luck!). That's a great rig so > it's worth the investment. > > Now, to find out why it went bad in the first place... > Best of luck. > > Gary > W3AM > > Dave Aabye wrote: > > > > Hello Gary, > > > > Thanks for the suggestion, which I believe has proven to be conclusive. > > > > I hooked my Variac to the primary and slowly increased the secondary > > voltage. > > The caps were disconnect from the rectifiers, so the transformer was "all by > > itself". At about 700 volts, the voltage started to jump just a bit. At > > maybe 750 v, the secondary emitted a puff of smoke with an accompanying > > hiss. > > > > I think it is clear that the transformer is shot. Time to call Peter Dahl! > > > > Again, thanks for your input. > > > > 73 de Dave > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
