K3 Buffer Mod
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I am about to attempt the N8LP K3 Buffer Mod for improved RX performance. It involves exchanging two, extremely small, surface-mount resistors.
I have never attempted as delicate a procedure as this. I am soliciting suggestions on how to do this without damaging the rf board. Jim K7EG _______________________________________________ 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 have never attempted as delicate a procedure as this. I am soliciting suggestions on how to do this without damaging the rf board.
I always use two (2) small temp-controlled soldering irons (Hakko 936). The idea is to heat both ends simultaneously to melt the solder without dwelling too long on the board. The parts likely have a small amount of adhesive under them so once the solder is melted, I push one end with a soldering iron while holding the other end still. This breaks the part free from the adhesive. Be certain the soldering irons aren't set too hot. 650 F is about right, 700F is probably OK, higher is a Bad Idea. There is little thermal mass here. The worst problem will be heat flow from the grounded end of one of the two resistors. Or, you may have an iron with a wide enough tip to heat both ends of the part - that will work too, just keep the temperature under control :-) I haven't had breakfast yet so I'm not thinking clearly; the RF board you damage maybe your own; YMMV, ... 73, Lyle KK7P _______________________________________________ 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 James Denneny
Jim
A Hakko tweezer handpiece makes removing surface mount parts easy, but it's a pricey solution for just a couple parts. Depending on the tools you have and the size of the part, you might consider using a pair of small cutters to snip the resistors in half before removing it. Then you can use a standard soldering iron and solder wick to clean the pads up. You're not trying to salvage the part, of course. Surface mount resistors are made with a ceramic substrate so they shatter easily. That's what you want to do--shatter the ceramic so that you can work on each end individually. The practicality of this approach depends on the part size, how much free room you have to access it and the size of your cutters. It works well for 1206 parts and OK for 805 size resistors, but I have not tried it with smaller devices. If there's a risk of damaging other components or a PCB trace, of course, don't use this approach. Jack Jim Denneny wrote: > I am about to attempt the N8LP K3 Buffer Mod for improved RX performance. It involves exchanging two, extremely small, surface-mount resistors. > > I have never attempted as delicate a procedure as this. I am soliciting suggestions on how to do this without damaging the rf board. > > Jim > K7EG > _______________________________________________ > 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 > > 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 James Denneny
At 09:48 AM 8/21/2008, Jim Denneny wrote...
>I am about to attempt the N8LP K3 Buffer Mod for improved RX >performance. It involves exchanging two, extremely small, >surface-mount resistors. Chip-quick ( http://www.chipquikinc.com/newsletters/cq_new_june_2004.htm ) is great for doing SMT rework. It's a low melting temperature alloy, which you use like solder. It mixes with the existing solder to make device removal easy. It doesn't take much. Without a rework station, it's about the only thing you can use for larger devices. If you were experienced in working with SMT, then it might be overkill for replacing just a resistor. But even if you've done SMT before, there's still the danger of lifting a pad when using just a soldering iron. Good stuff if you want to do it yourself with minimal risk to an expensive board. For soldering the new component, I just make sure the pads are lightly tinned, hold the component in place with a toothpick, and lightly touch each joint with the iron. _______________________________________________ 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 James Denneny
This is about the simplest SMD work one can do, but I would *strongly* recommend you find a scrap SMD board and practice removing and soldering a few resistors first. Almost any scrap board (like an old modem) should have some resistors. I've not had any problems removing components like Rs and Cs using a single Circuit Specialists clone of the Hakko 936 with a 1.6mm chisel tip at 700 degrees. I found the resistors easily slide off after alternately heating each side, but you definitely should practice first. |
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G'day,
What is this mod? regards, Mike VP8NO ----- Original Message ----- From: "Bill W4ZV" <[hidden email]> To: <[hidden email]> Sent: Thursday, August 21, 2008 12:51 PM Subject: Re: [Elecraft] K3 Buffer Mod | | | | James Denneny wrote: | > | > I am about to attempt the N8LP K3 Buffer Mod for improved RX performance. | > It involves exchanging two, extremely small, surface-mount resistors. | > | | This is about the simplest SMD work one can do, but I would *strongly* | recommend you find a scrap SMD board and practice removing and soldering a | few resistors first. Almost any scrap board (like an old modem) should have | some resistors. I've not had any problems removing components like Rs and | Cs using a single Circuit Specialists clone of the Hakko 936 with a 1.6mm | chisel tip at 700 degrees. I found the resistors easily slide off after | alternately heating each side, but you definitely should practice first. | | -- | View this message in context: http://n2.nabble.com/K3-Buffer-Mod-tp738458p740658.html | Sent from the Elecraft mailing list archive at Nabble.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 | | No virus found in this incoming message. | Checked by AVG - http://www.avg.com | Version: 8.0.138 / Virus Database: 270.6.6/1625 - Release Date: 21/08/2008 06:04 | | | _______________________________________________ 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 Mike S-8
<quote author="Mike S-8"> At 09:48 AM 8/21/2008, Jim Denneny wrote... >I am about to attempt the N8LP K3 Buffer Mod for improved RX >performance. It involves exchanging two, extremely small, >surface-mount resistors. Chip-quick ( http://www.chipquikinc.com/newsletters/cq_new_june_2004.htm ) is great for doing SMT rework. It's a low melting temperature alloy, which you use like solder. It mixes with the existing solder to make device removal easy. It doesn't take much. Although I am a big fan of ChipQuik you should try it on an old PC board before you try it on something that might break your heart if you fail. ChipQuik can send a part flying (along with a trail of molten ChipQuik) if the part has been tacked down with an adhesive and requires a little pressure. Once you get the hang of it, on a multipin IC, it can be a life saver. I don't think I would use it on a resistor or cap though. I would go with the single iron back and forth or the two iron method. Tom, AK2B |
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There's one easy trick I learned a while back.
Actually add solder to each end of the R or C to be removed. This creates a larger thermal mass that doesn't cool and harden as quickly, and gives you time to get the other end melted too. Then the part slides right off. As has been recommended before, practice first on some junk pc board with SMD parts on it. Really easy technique. Good luck and 73 Bob N6WG ----- Original Message ----- From: "Tom AK2B" <[hidden email]> To: <[hidden email]> Sent: Thursday, August 21, 2008 10:43 AM Subject: Re: [Elecraft] K3 Buffer Mod > > > > At 09:48 AM 8/21/2008, Jim Denneny wrote... > >I am about to attempt the N8LP K3 Buffer Mod for improved RX > >performance. It involves exchanging two, extremely small, > >surface-mount resistors. > > Chip-quick ( > http://www.chipquikinc.com/newsletters/cq_new_june_2004.htm ) is > for doing SMT rework. It's a low melting temperature alloy, which you > use like solder. It mixes with the existing solder to make device > removal easy. It doesn't take much. > > Although I am a big fan of ChipQuik you should try it on an old PC board > before you try it on something that might break your heart if you fail. > ChipQuik can send a part flying (along with a trail of molten ChipQuik) if > the part has been tacked down with an adhesive and requires a little > pressure. Once you get the hang of it, on a multipin IC, it can be a life > saver. I don't think I would use it on a resistor or cap though. I would go > with the single iron back and forth or the two iron method. > > Tom, AK2B > -- > View this message in context: http://n2.nabble.com/K3-Buffer-Mod-tp738458p740797.html > Sent from the Elecraft mailing list archive at Nabble.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 _______________________________________________ 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 Bill W4ZV
Should I expect any negative impacts if I used regular resistors in place
of SM resistors for this mod? N2TK, Tony -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill W4ZV Sent: Thursday, August 21, 2008 12:52 PM To: [hidden email] Subject: Re: [Elecraft] K3 Buffer Mod James Denneny wrote: > > I am about to attempt the N8LP K3 Buffer Mod for improved RX performance. > It involves exchanging two, extremely small, surface-mount resistors. > This is about the simplest SMD work one can do, but I would *strongly* recommend you find a scrap SMD board and practice removing and soldering a few resistors first. Almost any scrap board (like an old modem) should have some resistors. I've not had any problems removing components like Rs and Cs using a single Circuit Specialists clone of the Hakko 936 with a 1.6mm chisel tip at 700 degrees. I found the resistors easily slide off after alternately heating each side, but you definitely should practice first. -- View this message in context: http://n2.nabble.com/K3-Buffer-Mod-tp738458p740658.html Sent from the Elecraft mailing list archive at Nabble.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 _______________________________________________ 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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