K3 - SMT mods
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David
I just used a 12 Watt Antex soldering iron type M, Maplin part number YU90X. They come with a pointed bit as standard. You also need solder wick (or Soldamop) Maplin part number N58AL and stainless steel tweezers. Working on the K3 might sound a little daunting, but one of my technicians used to work on SMD parts in his previous job and told me the easy way to work on them for changing the odd part or two... 1. Using the solder wick, remove the solder from both ends of the resistor/capacitor. 2. The joints should look "dry", holding the component in the tweezers heat one end with the soldering iron and lift that end slightly, then warm the other end. This was the first time I had worked on surface mount, although I have more than 20 years experience of PCB work from a previous job. An amateur grade heat gun on an expensive K3 sounds like a disaster in the making to me! Proper SMD hot air re-work stations cost thousands, they cost that much for a reason. 73 Dave, G4AON K3/100 #80 with AGC and CW waveform modifications =================================================== I need to make the K3 mods and was wondering if an investment in a heat gun would be worthwhile (it's not like SMT is going to go away!). 73 de M0XDF, K3 #174 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I am in no great hurry to do any mods, since the lack of them is not making any noticeable difference to my K3. My concern is that when trying to use the desoldering braid, enough solder will remain to keep the part in place, and one will end up doing it too many times and eventually lifting a trace. One list member already reported doing that. I don't have any scrap boards with SMD components to experiment on, but since all that is needed is to remove a couple of parts, I planned to try this: Using a bit of stiff copper wire, wind a tight coil of 2 or 3 turns so that it is a tight fit on the end of the soldering iron bit, and turn the ends of the coil so that I end up with a bit with two prongs extending forward of it for a few mm, spaced apart by the width of the SMD part. When the iron is heated up, it will heat the copper wire extension as well. I will then apply the bit so that the wire prongs are either side of the part to be removed. The idea is that the solder will be melted on both sides of the SMD part simultaneously and the part can immediately be moved. If necessary, the solder wick can then be used to clean up the area. Does anyone think this would work?
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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In reply to this post by Dave, G4AON
If you have that Circuit Specialists soldering station, they sell a SMD iron
for it (has two probes) for $30. That is what I used to make the HAGC mod to my K3. Works great. Phil - AD5X _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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One thing I haven't heard mention so far: I believe these boards are made
to the latest ROHS, therefore lead-free solder is used, therefore the de-soldering temperature is higher than some irons might be capable of. At my place of work we had to replace all our irons with higher temperature spec versions and we use 385C for manual soldering. Can't remember what the de-solderer uses. For the odd job you have to do, it might not matter very much or might seem slow. That could be a bad thing because you don't want the iron to linger on the joint for longer than is necessary, this can lead to track-lifting. As far as amateurs are concerned, replacing with a new part does not need the same solder as the manufacturer used. You can use your regular solder or paste as before at the temperature you used to use. David G3UNA _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Dave, G4AON
> This was the first time I had worked on surface mount, although I
> have more than 20 years experience of PCB work from a previous job. > > An amateur grade heat gun on an expensive K3 sounds like a disaster > in the making to me! Proper SMD hot air re-work stations cost > thousands, they cost that much for a reason. I picked up a temperature and airflow-controlled hot-air rework tool for about $100. Different tips allow me to control airflow to the precise area of the board to be worked. It makes removing parts a piece of cake. I have even used it on things like chip sockets on through-hole boards. I got it from these guys: http://circuitspecialists.com They have good, inexpensive solder and rework stations too. -- Brian Lloyd Granite Bay Montessori brian AT gbmontessori DOT com 9330 Sierra College Blvd. +1.916.367.2131 (voice) Roseville, CA 95661, USA http://www.gbmontessori.com I fly because it releases my mind from the tyranny of petty things . . . Antoine de Saint-Exupéry PGP key ID: 12095C52A32A1B6C PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C -- 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Julian, G4ILO
> I am in no great hurry to do any mods, since the lack of them is not
> making > any noticeable difference to my K3. My concern is that when trying > to use > the desoldering braid, enough solder will remain to keep the part in > place, > and one will end up doing it too many times and eventually lifting a > trace. > One list member already reported doing that. > > I don't have any scrap boards with SMD components to experiment on, > but > since all that is needed is to remove a couple of parts, I planned > to try > this: Instead of "trying" things, why not use the tools that professionals use? It just isn't that hard nor is it all that expensive. My temperature-controlled hot-air gun just wasn't all that expensive. > Using a bit of stiff copper wire, wind a tight coil of 2 or 3 turns > so that > it is a tight fit on the end of the soldering iron bit, and turn the > ends of > the coil so that I end up with a bit with two prongs extending > forward of it > for a few mm, spaced apart by the width of the SMD part. > > When the iron is heated up, it will heat the copper wire extension > as well. > I will then apply the bit so that the wire prongs are either side of > the > part to be removed. The idea is that the solder will be melted on > both sides > of the SMD part simultaneously and the part can immediately be > moved. If > necessary, the solder wick can then be used to clean up the area. > > Does anyone think this would work? It might, and it might damage the board. I guarantee the hot-air gun will work better and be less prone to damage. And temperature control is important. Using a 500C hot-air gun is going to burn up your board. I can set the air temp on mine to 250C to melt the solder without frying the board. Look at it this way too: if you are building things you are going to start using SMT. So get the right tool before you ruin something. -- 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I'm sorry, Brian, but here in the real world, spending $100 on a tool to do a one-off modification just isn't an option.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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On Jun 22, 2008, at 1:40 PM, Ron D'Eau Claire wrote: > For many Hams today one of the most interesting parts of Amateur > Radio is > figuring out how to get something done without all the resources > we'd expect > to find in a well-financed laboratory. It isn't all about money, > although > most of us live on a strict budget. It's the challenge to find a way > and > develop the skills to do the job with the resources at hand that > gives some > of us as much satisfaction as a DXCC certificate or top score in a > contest > does for others. Certainly. Lots of people "roll their own". I love vacuum tubes like to resurrect boat anchors. But I suspect that most of us own tools that we purchased rather than constructed. I suspect almost everyone here has a set of screwdrivers, a set of sockets, needle-nose pliers and various cutters, a soldering iron, a DMM, etc., that they purchased. I am betting that most people have several hundred dollars invested in tools. Of course, tools last a long time. I am still using hand tools I purchased 40 years ago. I know that I am not about to manufacture my own hot-air rework tool, especially when I can purchase one for $79(us). (http://www.circuitspecialists.com/prod.itml/icOid/9445 ) I also know that I am going to continue to encounter SMT if I continue playing with amateur radio. So far the sub-$100(us) hot-air tool has worked just fine. It has been used to build several softrock boards and even to remove components installed backwards on the K2. (11-year-old kids get in a hurry and aren't good about reading instructions carefully.) BTW, a hot-air rework tool beats the snot out of solder-wick and a solder-sucker for getting parts out of a board. So, I applaud those who manage to "make do" with what is on hand. OTOH, I wanted to point out that there are relatively low-cost tools designed to do the job. Now people get to decide for themselves how they want to spend their time and their money. -- 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Brian,
That one part of your argument I have shown below says it all for me. Good tools *will* last a long time and serve their purpose very well over their lifetime. Some inexpensive tools are just not up to the task, and sometimes fail after a few uses. I consider tool purchases carefully - both from a cost perspective and a durability perspective. I would not want to spend a lot of money for a one off use - better to rent or borrow for that purpose. Substitute tools should be used carefully because they can fail in ways to cause injury - but I am thinking more along the lines of wrenches that can slip, but I give similar consideration to the soldering tools I purchase. Is it up to the job I want to do? Will it last sufficiently long for my purposes? Can I justify the cost based on my use over the tool's lifetime (or mine), etc. Each person has a different criteria for selection, the choice is an individual one. 73, Don W3FPR Brian Lloyd wrote: > Of course, tools last a long time. I am still using hand tools I > purchased 40 years ago. > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Brian Lloyd-6
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In reply to this post by Phil Salas
Unfortunately, they all seam to be 110v input! pity, because there is
some good stuff on there. I guess I could use a 110 to 240v transformer. -- As a well spent day brings happy sleep, so life well used brings happy death. -Leonardo da Vinci, painter, engineer, musician, and scientist (1452-1519) On 22 Jun 2008, at 12:59, Phil & Debbie Salas wrote: > If you have that Circuit Specialists soldering station, they sell a > SMD iron for it (has two probes) for $30. That is what I used to > make the HAGC mod to my K3. Works great. > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Brian Lloyd-6
If I was 40 years younger then buying such a tool might be a good investment, like many of the tools I currently own. But failing eyesight and unsteady hands mean that construction involving SMT parts is now out of the question, and any electronic constructional activity has become more of a chore than a pleasure, so at this point in my life it would be a complete waste of money. Hence my rather abrubt dismissal of your suggestion. Elecraft's decision to make the K3 a no-solder kit was exactly the right one for me. I am going to have to do without this modification unless I can find a way to do it without risk of harming the K3 and without requiring any special equipment. I have had enough feedback to suggest that my idea should work (though still suggesting that I should try it first on something disposable.)
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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> If I was 40 years younger then buying such a tool might be a good
> investment, like many of the tools I currently own. But failing > eyesight and > unsteady hands mean that construction involving SMT parts is now out > of the > question, and any electronic constructional activity has become more > of a > chore than a pleasure, so at this point in my life it would be a > complete > waste of money. Hence my rather abrubt dismissal of your suggestion. No worries. I didn't take it personally. I am finding that I am more shaky than I was years ago. I also discovered that I don't want to drink two cups of coffee before trying to stuff an SMT board. :-) But just as a point, the 4th and 5th year students do not have the best fine-motor coordination either. They really like the SMT work as they can be a bit sloppy and still achieve almost perfect results. When the solder paste melts, surface tension pulls the components into alignment with the pads on the board. It is amazing to watch all the little parts move around and line up where they are supposed to be. It looks like something out of a science-fiction movie. I wish I had gotten a picture of two of my 5th-year students (girls). They were stuffing a SoftRock board with the SMT parts in prep for baking. They had taped paper napkins over their faces like surgical masks and were working over my ring magnifier. One girl was applying solder paste with a syringe and the other was placing the parts with tweezers. When I came over to where they were working they shooed me away explaining that they were involved in a very delicate operation and that I was not invited into the operating room unless I had "scrubbed up". The board came out perfectly after baking. > Elecraft's decision to make the K3 a no-solder kit was exactly the > right one > for me. I am going to have to do without this modification unless I > can find > a way to do it without risk of harming the K3 and without requiring > any > special equipment. I have had enough feedback to suggest that my > idea should > work (though still suggesting that I should try it first on something > disposable.) You might want to get a SoftRock lite board. They are cheap and very cool to play with. You can get your feet wet with both SMT and SDR all at once and all for the cost of about $30(us). -- Brian Lloyd Granite Bay Montessori brian AT gbmontessori DOT com 9330 Sierra College Blvd. +1.916.367.2131 (voice) Roseville, CA 95661, USA http://www.gbmontessori.com I fly because it releases my mind from the tyranny of petty things . . . — Antoine de Saint-Exupéry PGP key ID: 12095C52A32A1B6C PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C -- 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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