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Author Topic: brazing /silver soldering help Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 04-29-2004 05:12 PM                        We are installing more grounding straps at one of our transmitter sites. the down side is that this 4" copper strapping has to be silver soldered. We have a brazing torch, but neither Mark or I know how to do this. Could someone either explain, or point me to an answer? Thanks Josh  |  IP: Logged Pete Wolla Film Handler Posts: 71 From: Tioga, ND, USA Registered: Jan 2003 posted 04-29-2004 05:55 PM                     Is that 4 inch wide? how thick? with plumbing clean with steel wool.flux and heat one side while feeding the solder on the other. its should flow to the heat. 4" may be a long way to pull it.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-29-2004 06:39 PM                     If I were doing this I'd probably invest in a good solder pot and alot of bars of silver solder. Dipping the fluxed 4" wide braid in a solder pot of silver solder to tin the ends of would be a good place to start. Then clean tinning the part that you want to attach the braid too and then heating them both up at the same time with a wide mouth torch to attach the braid would work well. Don't expect to do this cheaply and still be able to do it correctly. It will cost you quite a bit just in solder to do the job right!! Also keep in mind that the melting point of silver solder is alot higher then normal 60/40 solder. Also don't forget your Braidguard solution to keep the braid pliable over the years . BTW....Silver soldering parts in transmitters is SOP. You guys ever think of starting a new web site... www.transmitter-tech.com ? Mark  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 04-29-2004 06:42 PM                        radio-tech has a nicer ring to it Also, perhaps you guys didnt catch the part about strapping, not braid. this stuff is a long roll of copper sheet, 4" wide. just a clairification....  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 04-29-2004 08:27 PM                     Hi Josh There are different grades and melting temps of silver solder. You will of course need an acid flux..and you will need to clean all the flux off post-soldering to prevent corrosion. A little silver solder goes a long way! It is good practice to use fire-brick, or there are these heat resistant tiles you can by. Nice thing about the tiles is that you can insert pins in them to act as fixturing. Apply the flux, and heat the flux so that it flows. Then you add the silver solder. Cut a pice of solder, hammer it flat, then put into the joint. Remember that a little tiny bit of silver solder goes a long way. Depending on what you are soldering, the metal needs to be heated evenly, thich can be a little tricky if you have a big piece being soldered to a smaller piece. Also, it is good practice to get a clean soldering surface by removing mechanically (sandpaper or file) any oxidation from the metal being soldered...not just relying on the acid flux to do the job. If you can, contact W & R scale models (brass model railroad importers and pattern makers). Bill McKown (spelling) has written some excellent articles in Mainline Modeler Magazine.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 04-29-2004 08:40 PM                        could I use mapp gas and a regular plumbing torch to use this stuff? I just cant get the hang of the oxy-acetelyne setup. Josh  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-29-2004 09:25 PM                     Being flat copper makes it far easier to solder. Just follow Wills instructions to the tee and it'll work fine. A wide mouth torch will help heat the wide area much more quickly. With OXY you may actually end up melting the copper as its way too hot . Mark  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 04-30-2004 12:52 AM                     A Bernz-O-Matic might work well for you. If need be, there are a few ways to prevent heat from spreading to unwanted areas. The "cheap way" is the ole wet t.p. or tissue trick. Another heat-sink trick is using an alligator clip or the like. If you want to keep solder within a limited area, there are some commericial coumpounds available. However, another old trick that works is drawing a fine "barrier line" with a good ole soft lead pencil. For some reason, this trick is also used in ceramic art work to keep a nice crisp line between glaze colors. I would be weary of using a pencil on hi-stress mechanical items, though. I have seen many a custom sheet-metal fabricator use a pencil for marking bend layouts. But we were taught in A & P school that this is a definate no-no 'cause the lead for some reason can create a stress riser which will lead to cracking.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 04-30-2004 01:49 AM                     Use MAPP gas torch. Those have been used for many years. The disposable cylinders run just a tad over 8 bucks, and the entire MAP Gas torch with the cylinder costs about 62 bucks or so at a good hardware store. MAPP Gas torches have been part of the took kit for radio station engineers for many years.They were also the salvation for refrigeration mechanics, too. Use SilFos(sp)for solder. It is very expensive, but well worth it. It runs about 45 bucks a pound. It comes in a tube in a stick form. Last week, I bonded 4-inch width copper bonding strap to station ground. With a MAPP Gas torch, it takes a matter of minutes. No flux needed, and the typical blow torch simply won't get the material hot enough to get the intermetallic bond needed for a good mechanical and electrical connection. 13 years ago, this was the same method I used when I installed the KBRC transmitter in the new building after we lost the orginal building to a flood. Regular 60/40 solder sucks, especially in outdoor applications where the bonding strap is subject to harsh enviroments. I use the MAPP gas torch for repairing busted ground radials as well. It takes about 3 seconds per radial after the bitter ends were rejoined. I believe MAPP Gas stands for Methyl-Acetylene Propadiene Propane.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 05-02-2004 04:43 PM                  quote: Will Kutler But we were taught in A & P school that this is a definate no-no.... Gosh Will, I didn't know you went to the Great Atlantic & Pacific Tea Company, (A&P - A midwest supermarket chain) box-boy school. I'm sure you learned a lot of "no-no" things there... such as not packing that carton of eggs under that 20 pound turkey, huh? Glad, you have had that formal training.... I'm sure Jenna would be proud! >>> Phil  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 05-02-2004 08:25 PM                     Paul, I believe we had a MAPP torch at the TV station. Never heard of that solder though. We had large riolls of silver solder and appropriate flux there...mainly for soldering the water circulation pipes. RCA originally installed the thrnsmitter with all silver soldered pipework so it had to be kept all the same...sort of like an old Tektronix scope which were all soldered with silver solder...ya had to stick to it or face metalurgic problems down the line with the connections. They even included a small roll attached to many of the chassis. Mark  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 05-03-2004 12:32 AM                     LOL Phil! But ya done BOMBED again..... I AM INVINCIBLE!!!!!!!!!!!!!!!!!!!!!!!! Right out of high school, I went on to study avaiation maintenance, where I became FAA licensed. Currently in mid-life carreer change finishing my BS in Engineering......  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 05-03-2004 08:33 PM                     Mark, Us old burned out refrigeration mechanics and un-burned out radio station engineers just love those MAPP Gas setups. We don't use silver solder on water pipes, just the regular plumber's solder because it melts at such a low temperature as compared to Silver-Phos Alloy which melts at about 1190 degrees F. Incidently, I was in error when I cited about 45 bucks a pound. It is more like 26 bucks a pound. The stuff I use comes in a one-pound tube that contains 28 each inch sticks. http://www.brazing.com/techguide/Solders/selection_chart.htm  |  IP: Logged

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