RE: [AMRadio] Drying out HV transformers / Chokes
My BC-610 plate transformer (open frame) is available free to pick up from Roundrock, Texas... I once rebuilt a Globe King 500 RF plate transformer, and made the secondary winding w/o a ct, to save wire, and use a bridge rectifier. I did a really good job with it, and vacuum impregnated it, baked it, and all that. Problem was however that when I went to reinstall the E I laminations, I only got about 95% of them dudes back on before I ran out of room. The core had shrunk on the mandrel when I rewound it. The consequence? The primary when excited with 120 vac was saturating (pulled 10 amps unloaded), and was only OK at 105 vac and below. Turned into a door stop, and then landfill. sigh. So Gary, if you rewind your 610 plate transformer, I have a suggestion. Whatever the turns ratio is, maintain that, BUT increase the number of primary turns at least 5% to avoid the problem that I had with core saturation at normal 2005 line voltage. Jim -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of GBrown Sent: Monday, September 19, 2005 5:07 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Drying out HV transformers / Chokes Read it closely, MY PLANS ARE TO REWIND IT. Thats about as plane as it gets. Regards, Gary...WZ1M - Original Message - From: Geoff [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Monday, September 19, 2005 5:50 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes GBrown wrote: Speaking of HV trannys for the BC-610. I have one with a shorted secondary. My plans are to rewind this hunk of iron and turn the primary into a dual voltage, 115/230. This tranny is from the E model. Would I have anyone out there that mite be interested? Also, the transformer has those big beautiful cast endbells. interested... in? rewinding it? Buying it? rewinding and retapping it for dual primaries? ya gotta talk a bit clearer than that, to communicate ;-) -- 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005
Re: [AMRadio] Drying out HV transformers / Chokes
I have several 2.5v and 10v rusty,dirty, and rattling UTC small can S series filament transformers that I want rebuild and would like to know a source for transformer varnish and potting material, wax,tar, or whatever. On pulling the cover off the most rattling around one I found only sections of corrugated cardboard to be the packing/potting material !!. Those were the cheapies made by UTC. Their higher quality transformers were potted with tar. Some of the older S series actually had louvres in the case for ventilation. These were essentially open frame transformers with a protective case against physical abuse. Later S series did use potting material. These were the lowest quality transformers UTC made, and their ratings are for intermittent amateur service. Don k4kyv
Re: [AMRadio] Drying out HV transformers / Chokes
I just took the back off of my HT-4B, which is similar to the BC-610, to take a look at the modulation transformer. It looks like a pick up with one hand object to me. The open frame ones with cast iron end-bells are heavier, but I still think it could be carried by one person using one arm. The BC 610E used those. The more modern hermetically sealed ones are pick u with one hand objects. Hopefully, they made them smaller and lighter by using more modern materials. Don K4KYV
Re: [AMRadio] Drying out HV transformers / Chokes
Regular floor varnish works just fine. You have to thin it with Zylene. The motor repair shop is a baking varnish. I use nomex paper when insulating rewinds. Its expensive but very very reliable. The tar is nothing more than the stuff roofers use on flat roofs. Its applied hot and cools down to a durable application. Should be able to chip a pound or two of one of the plugs of tar. I bet they would give it to you. The nomex paper is about $12.00 for a small sheet. There are different thicknesses. Regards, Gary...WZ1M - Original Message - From: Larry Will [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Sunday, September 18, 2005 7:49 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes Don, I found a source for transformer varnish on the internet. That varnish is very volatile and you may have trouble getting it as an individual. (the flash point is around 70 degrees with a spark as I remember and it has a short shelf life according to the mfgr.). I had no trouble but I am a licensed Professional Engineer. An option for the units is to find a motor rebuild shop. They usually have a 55 gallon drum of it that they dip the rewound motors into when they are done. I sure they would do it for you for a modest fee. I have no source on the tar or fish paper etc. Larry At 01:00 PM 9/18/2005, you wrote: Hello Larry and All, I have several 2.5v and 10v rusty,dirty, and rattling UTC small can S series filament transformers that I want rebuild and would like to know a source for transformer varnish and potting material, wax,tar, or whatever. On pulling the cover off the most rattling around one I found only sections of corrugated cardboard to be the packing/potting material !!. I would like to use something better and improve the heat transfer as these seem to be really small construction for the rated current. I intend to use the 10v units for 813/814/805 family. Any suggestions would be appreciated. Bill KB3DKS/1 -Original Message- From: Larry Will [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Discussion of AM Radio amradio@mailman.qth.net Sent: Sun, 18 Sep 2005 10:41:41 -0400 Subject: Re: [AMRadio] Drying out HV transformers / Chokes Don, Here is the section in my article from ER Magazine on rebuilding an RCA BTA-1R1 on the homemade over I used with great sucess. all you need is a thermostatically controlled hotplate a thermometer and a hood. .from my RCA BTA-1R! article in ER. A check of all the iron with a 1000V 1000 megohm ohmmeter showed excessive leakage (less than 1000 megs) in the modulation reactor, the driver plate transformer, and the control transformer. The control transformer makes 110VAC for relays and lamps from the 240V input. The smaller transformers were baked in the kitchen oven at 140 degrees F for 5 hours. For the very heavy 50 henry modulation reactor, I fashioned a homemade oven using a thermostatically controlled single burner hotplate and a hood made from an old water heater jacket (Figure 1). This allowed me to cook the transformer out in the garage near the rig. An oven thermometer allowed me to set the oven temperature to 140 degrees F and after 25 hours of baking, the leakage was cured. All of these transformers and chokes were then dipped in transformer varnish to re-seal the winding from new moisture incursion. Regards, Larry W3LW __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] Drying out HV transformers / Chokes
Speaking of HV trannys for the BC-610. I have one with a shorted secondary. My plans are to rewind this hunk of iron and turn the primary into a dual voltage, 115/230. This tranny is from the E model. Would I have anyone out there that mite be interested? Also, the transformer has those big beautiful cast endbells. Regards, Gary...WZ1M - Original Message - From: Geoff [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Sunday, September 18, 2005 11:12 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes Barrie Smith wrote: Are you sure you're talking about a BC-610 modulation transformer? I just took the back off of my HT-4B, which is similar to the BC-610, to take a look at the modulation transformer. It looks like a pick up with one hand object to me. BC-610 Plate Transformer, is what they were talking about, and it's -not- a ['pick up with one hand'] critter. Neither, for that matter, is the '610 Mod xfrmr, but it -is- smaller than the plate xfrmr. -- 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] Drying out HV transformers / Chokes
GBrown wrote: Speaking of HV trannys for the BC-610. I have one with a shorted secondary. My plans are to rewind this hunk of iron and turn the primary into a dual voltage, 115/230. This tranny is from the E model. Would I have anyone out there that mite be interested? Also, the transformer has those big beautiful cast endbells. interested... in? rewinding it? Buying it? rewinding and retapping it for dual primaries? ya gotta talk a bit clearer than that, to communicate ;-) -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Drying out HV transformers / Chokes
Read it closely, MY PLANS ARE TO REWIND IT. Thats about as plane as it gets. Regards, Gary...WZ1M - Original Message - From: Geoff [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Monday, September 19, 2005 5:50 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes GBrown wrote: Speaking of HV trannys for the BC-610. I have one with a shorted secondary. My plans are to rewind this hunk of iron and turn the primary into a dual voltage, 115/230. This tranny is from the E model. Would I have anyone out there that mite be interested? Also, the transformer has those big beautiful cast endbells. interested... in? rewinding it? Buying it? rewinding and retapping it for dual primaries? ya gotta talk a bit clearer than that, to communicate ;-) -- 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] Drying out HV transformers / Chokes
So, you want someone to rewind it for you? You want someone to buy it, after you've rewound it? You said My plans are to rewind this hunk of iron and turn the primary into a dual voltage, 115/230. ... Would I have anyone out there that mite be interested? IN WHAT? I'm sorry, you are -NOT- being clear about it. There's more than two ways that your statement could be interpreted. That's not 'plain'[sic]. -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Drying out HV transformers / Chokes
Low-voltage DC on the windings would do it. It would be tricky to figure a current that would produce enough heat without toasting anything, though. Probably something around the maximum operating current would do it, over time. I would put the primary and secondary windings in series, and heat the whole core. You might try to arrange the connections to approximately cancel the DC flux in the core. Put the core in a blanket so the heat builds up, and monitor its temperature. My guess is it will take days to build up the heat. You want to heat it up so it is warm to hot to the touch, (maybe 140F / 60C), but you don't want to scorch it. Another thought is to get a few electric space heaters and point them at the unit, and let them heat it up. Again, monitor its temperature. With this kind of heating power, you really need to watch it closely. Bacon, WA3WDR - Original Message - From: Don Lemley [EMAIL PROTECTED] To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; AMRadio@mailman.qth.net Sent: Sunday, September 18, 2005 12:51 AM Subject: [AMRadio] Drying out HV transformers / Chokes Hi all, Ok, I know this has been covered here before, but is there a consensus on how to get the moisture out of HV plate transformers and chokes, so they won't arc on me. And before everyone jumps in with the quick just put it in an oven on xxx degrees for yy hours, I am working with the iron from a Broadcast transmitter, specifically, the Gates BC-1G so these things are 100, 150 lbs each, and my XYL would REALLY not like it if I tried to put them in her fancy oven. They have been sitting in an un-conditioned but dry hanger/garage for several years, so I am certain they have soaked up a good deal of moisture over that time. Thanks for any suggestions, Don - W8HRQ _ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] Drying out HV transformers / Chokes
I have a modulation XFMR that was under muddy water for 6 months. I thought it had some how floated away in the Spring, Tx flood of 94, But I just didn't understand how it would be possible. That's another story, where was I, Oh yeh, the XFMR was found and the mud was off of it. It was let to stand in the sun for about 3 months under shed. I then measured 1000 ohms from any winding to another and to ground. I took the end caps off exposing the coil, rust and mud. Washed it out some more and decided to put it on the shelf in a un-air conditioned office that no one used, where the temp would reach 120-140 every day in the summer. I was thinking I would rewind it some day. But alas, 6 months later all the readings were infinite. To be safe it was mounted on a wooden shelf in the XMTR and has been working for the last 7-8 years. Modulator is four 813s with 2500 volts on the plates, 800 on the screens and about -100 on the grids. This modulator will pump out some PTP voltage. I was really surprised at the come back of this XFMR. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Don Lemley Sent: Saturday, September 17, 2005 11:51 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; AMRadio@mailman.qth.net Subject: [AMRadio] Drying out HV transformers / Chokes Hi all, Ok, I know this has been covered here before, but is there a consensus on how to get the moisture out of HV plate transformers and chokes, so they won't arc on me. And before everyone jumps in with the quick just put it in an oven on xxx degrees for yy hours, I am working with the iron from a Broadcast transmitter, specifically, the Gates BC-1G so these things are 100, 150 lbs each, and my XYL would REALLY not like it if I tried to put them in her fancy oven. They have been sitting in an un-conditioned but dry hanger/garage for several years, so I am certain they have soaked up a good deal of moisture over that time. Thanks for any suggestions, Don - W8HRQ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] Drying out HV transformers / Chokes
Hello Larry and All, I have several 2.5v and 10v rusty,dirty, and rattling UTC small can S series filament transformers that I want rebuild and would like to know a source for transformer varnish and potting material, wax,tar, or whatever. On pulling the cover off the most rattling around one I found only sections of corrugated cardboard to be the packing/potting material !!. I would like to use something better and improve the heat transfer as these seem to be really small construction for the rated current. I intend to use the 10v units for 813/814/805 family. Any suggestions would be appreciated. Bill KB3DKS/1 -Original Message- From: Larry Will [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Discussion of AM Radio amradio@mailman.qth.net Sent: Sun, 18 Sep 2005 10:41:41 -0400 Subject: Re: [AMRadio] Drying out HV transformers / Chokes Don, Here is the section in my article from ER Magazine on rebuilding an RCA BTA-1R1 on the homemade over I used with great sucess. all you need is a thermostatically controlled hotplate a thermometer and a hood. .from my RCA BTA-1R! article in ER. A check of all the iron with a 1000V 1000 megohm ohmmeter showed excessive leakage (less than 1000 megs) in the modulation reactor, the driver plate transformer, and the control transformer. The control transformer makes 110VAC for relays and lamps from the 240V input. The smaller transformers were baked in the kitchen oven at 140 degrees F for 5 hours. For the very heavy 50 henry modulation reactor, I fashioned a homemade oven using a thermostatically controlled single burner hotplate and a hood made from an old water heater jacket (Figure 1). This allowed me to cook the transformer out in the garage near the rig. An oven thermometer allowed me to set the oven temperature to 140 degrees F and after 25 hours of baking, the leakage was cured. All of these transformers and chokes were then dipped in transformer varnish to re-seal the winding from new moisture incursion. Regards, Larry W3LW
Re: [AMRadio] Drying out HV transformers / Chokes
I'm sure may be too simplistic to work but. why not put the xformer in the trunk of a car and leave it there, outside in the sun, for a week or month. Here in KY that works for most everything. I've dried apples this way ;-) Joe N4NAS Joe[EMAIL PROTECTED] From: G. TAYLOR [EMAIL PROTECTED] Reply-To: Discussion of AM Radio amradio@mailman.qth.net To: [EMAIL PROTECTED],Discussion of AM Radio amradio@mailman.qth.net Subject: Re: [AMRadio] Drying out HV transformers / Chokes Date: Sun, 18 Sep 2005 07:22:03 -0700 (PDT) Don, I suspect they may not be very wet if they haven't been in contact with water or condensation. I bought a CVM-5 that had been in an outside shed that was hit by a tornado. It was rusted, there was a roof over it but hardly any walls left. Any driven rain would have gotten on it, and it was in high humidity.(Alabama) But since they are so rare, I bought it anyway. Upon checking, it had about 1-2 megs to ground. If I'd needed in then, I'd probably tried it at that level. One meg. per 1,000 volts used to be the rule. But I put it in my basement Ham Shack in Alabama and it set there in the dry for about a year. I kept checking it and it steadly was going up. When I was ready to use it, for my HB 810's x 810's it read infinity! No heat, not anything but a dry heated and cooled basement! They should be checked with a megger though, It applies a DC voltage usually 500, or 1,000 volts. Most electricians, or any motor shop has these. GL Gary WB8BEM/8 Ok, I know this has been covered here before, but is there a consensus on how to get the moisture out of HV plate transformers and chokes, so they won't arc on me. And before everyone jumps in with the quick just put it in an oven on xxx degrees for yy hours, I am working with the iron from a Broadcast transmitter, specifically, the Gates BC-1G so these things are 100, 150 lbs each, and my XYL would REALLY not like it if I tried to put them in her fancy oven. They have been sitting in an un-conditioned but dry hanger/garage for several years, so I am certain they have soaked up a good deal of moisture over that time. Thanks for any suggestions, Don - W8HRQ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] Drying out HV transformers / Chokes
Hey Joe, that's 140 degrees F without the thermostat being necessary!. Great Idea! - Original Message - From: Joe A. Taylor [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Sunday, September 18, 2005 2:09 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes I'm sure may be too simplistic to work but. why not put the xformer in the trunk of a car and leave it there, outside in the sun, for a week or month. Here in KY that works for most everything. I've dried apples this way ;-) Joe N4NAS Joe[EMAIL PROTECTED]
RE: [AMRadio] Drying out HV transformers / Chokes
Hmmm, been most interesting. If I tried this with my 1999 Dodge Stratus, and my open frame BC-610 transformer, two things would occur: 1.) rust since my trunk seal leaks 2.) my gas mileage will suffer noticeably as well as car handling and maybe, 3.) If I get into an accident, the dang thing might smash me where I sit in the drivers seat. A BC-610 transformer flying through the air is not easily stopped! Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Mike Dorworth,K4XM Sent: Sunday, September 18, 2005 1:24 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Drying out HV transformers / Chokes Hey Joe, that's 140 degrees F without the thermostat being necessary!. Great Idea! - Original Message - From: Joe A. Taylor [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Sunday, September 18, 2005 2:09 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes I'm sure may be too simplistic to work but. why not put the xformer in the trunk of a car and leave it there, outside in the sun, for a week or month. Here in KY that works for most everything. I've dried apples this way ;-) Joe N4NAS Joe[EMAIL PROTECTED] __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005
RE: [AMRadio] Drying out HV transformers / Chokes
The Idea is for us rednecks, that have a car sitting around that we don't drive, is not drivable, or we can't afford to buy gas for it. Truth be known, that a totally sealed up small space such as a trunk of a car, may not work to well because the air saturation with water would probably occur before the XRMR was depleted of water. Perhaps you could open the trunk once in while on a day of low humidity and then close it back up for a while longer. Of course if you did drive it around and can afford the gas then perhaps a positive crank case ventilated vehicle could be modified so that the air intake for the crank case came from the trunk. HIHI I can see the next Jeeves cartoon now! John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Sunday, September 18, 2005 4:50 PM To: Mike Dorworth, K4XM; Discussion of AM Radio Subject: RE: [AMRadio] Drying out HV transformers / Chokes Hmmm, been most interesting. If I tried this with my 1999 Dodge Stratus, and my open frame BC-610 transformer, two things would occur: 1.) rust since my trunk seal leaks 2.) my gas mileage will suffer noticeably as well as car handling and maybe, 3.) If I get into an accident, the dang thing might smash me where I sit in the drivers seat. A BC-610 transformer flying through the air is not easily stopped! Regards, Jim WD5JKO
Re: [AMRadio] Drying out HV transformers / Chokes
the drivers seat. A BC-610 transformer flying through the air is not easily stopped! It is equally difficult to start. I purchased one at a flea market and it took three people to get it into my motor home. When I got home I had to do it alone and it is still sitting just inside...about 2 to spare...the garage door. I have designed a carrier for it that I am making out of a file cabinet set of casters. BUT the shack is up stairs. So I am thinking it will be easier to move the shack down to the garage and build the linear around the transformer than to try to get it upstairs!! Jim Isbell If you are not living on the edge, well then, you are just taking up too much space.
Re: [AMRadio] Drying out HV transformers / Chokes
Are you sure you're talking about a BC-610 modulation transformer? I just took the back off of my HT-4B, which is similar to the BC-610, to take a look at the modulation transformer. It looks like a pick up with one hand object to me. Barrie, W7ALW - Original Message - From: Jim Isbell, W5JAI [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Sunday, September 18, 2005 5:04 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes the drivers seat. A BC-610 transformer flying through the air is not easily stopped! It is equally difficult to start. I purchased one at a flea market and it took three people to get it into my motor home. When I got home I had to do it alone and it is still sitting just inside...about 2 to spare...the garage door. I have designed a carrier for it that I am making out of a file cabinet set of casters. BUT the shack is up stairs. So I am thinking it will be easier to move the shack down to the garage and build the linear around the transformer than to try to get it upstairs!! Jim Isbell If you are not living on the edge, well then, you are just taking up too much space. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] Drying out HV transformers / Chokes
I was refering to the old style open frame plate transformerhernia maker -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Barrie Smith Sent: Sunday, September 18, 2005 6:15 PM To: [EMAIL PROTECTED]; Discussion of AM Radio Subject: Re: [AMRadio] Drying out HV transformers / Chokes Are you sure you're talking about a BC-610 modulation transformer? I just took the back off of my HT-4B, which is similar to the BC-610, to take a look at the modulation transformer. It looks like a pick up with one hand object to me. Barrie, W7ALW - Original Message - From: Jim Isbell, W5JAI [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Sunday, September 18, 2005 5:04 PM Subject: Re: [AMRadio] Drying out HV transformers / Chokes the drivers seat. A BC-610 transformer flying through the air is not easily stopped! It is equally difficult to start. I purchased one at a flea market and it took three people to get it into my motor home. When I got home I had to do it alone and it is still sitting just inside...about 2 to spare...the garage door. I have designed a carrier for it that I am making out of a file cabinet set of casters. BUT the shack is up stairs. So I am thinking it will be easier to move the shack down to the garage and build the linear around the transformer than to try to get it upstairs!! Jim Isbell If you are not living on the edge, well then, you are just taking up too much space. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.344 / Virus Database: 267.11.1/104 - Release Date: 9/16/2005
Re: [AMRadio] Drying out HV transformers / Chokes
Don, I found a source for transformer varnish on the internet. That varnish is very volatile and you may have trouble getting it as an individual. (the flash point is around 70 degrees with a spark as I remember and it has a short shelf life according to the mfgr.). I had no trouble but I am a licensed Professional Engineer. An option for the units is to find a motor rebuild shop. They usually have a 55 gallon drum of it that they dip the rewound motors into when they are done. I sure they would do it for you for a modest fee. I have no source on the tar or fish paper etc. Larry At 01:00 PM 9/18/2005, you wrote: Hello Larry and All, I have several 2.5v and 10v rusty,dirty, and rattling UTC small can S series filament transformers that I want rebuild and would like to know a source for transformer varnish and potting material, wax,tar, or whatever. On pulling the cover off the most rattling around one I found only sections of corrugated cardboard to be the packing/potting material !!. I would like to use something better and improve the heat transfer as these seem to be really small construction for the rated current. I intend to use the 10v units for 813/814/805 family. Any suggestions would be appreciated. Bill KB3DKS/1 -Original Message- From: Larry Will [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Discussion of AM Radio amradio@mailman.qth.net Sent: Sun, 18 Sep 2005 10:41:41 -0400 Subject: Re: [AMRadio] Drying out HV transformers / Chokes Don, Here is the section in my article from ER Magazine on rebuilding an RCA BTA-1R1 on the homemade over I used with great sucess. all you need is a thermostatically controlled hotplate a thermometer and a hood. .from my RCA BTA-1R! article in ER. A check of all the iron with a 1000V 1000 megohm ohmmeter showed excessive leakage (less than 1000 megs) in the modulation reactor, the driver plate transformer, and the control transformer. The control transformer makes 110VAC for relays and lamps from the 240V input. The smaller transformers were baked in the kitchen oven at 140 degrees F for 5 hours. For the very heavy 50 henry modulation reactor, I fashioned a homemade oven using a thermostatically controlled single burner hotplate and a hood made from an old water heater jacket (Figure 1). This allowed me to cook the transformer out in the garage near the rig. An oven thermometer allowed me to set the oven temperature to 140 degrees F and after 25 hours of baking, the leakage was cured. All of these transformers and chokes were then dipped in transformer varnish to re-seal the winding from new moisture incursion. Regards, Larry W3LW __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
