K3 Audio Upgrade Mod
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Today I got around to installing in
my K3 the audio upgrade kit that arrived a couple of weeks ago. The first part
of the kit involves swapping an RFC on the main PCB with one that has a lower
resistance. (FYI, I measured the resistance of the original choke as 0.4 ohms,
and of the new choke as 0.1 ohms – hard to imagine the new choke would
make that much difference!). The instructions give a “short”
and a “long” method of installing the choke. The “short”
method involves cutting a circuit board trace. I elected to do the “long”
mod and timed myself. Start to finish it took 15 minutes! I highly recommend
folks do the long method, and also that Elecraft delete the short method as an
option. It just isn’t necessary and, besides, who wants to mess up that
beautiful circuit board? The second part of the kit involves
shunting two resistors with 51 ohm resistors, and here also Elecraft
gives two options: one is to solder 1/8w through-hole resistors onto the IO
board, and the other is to solder two tiny SMT (surface mount ) resistors
piggy-back onto existing SMT resistors. The kit comes with both kinds of resistors.
I elected to do the SMT version of the mod, and here I’d recommend
that owners opt for the other method. I don’t see any advantage to doing
the SMT version. It takes a very steady hand, a very small-tipped
soldering iron, and very good eyesight to piggy-back the two SMT resistors into
the circuit, and I just don’t see the reason for the hassle. It would
take five minutes to install the through-hole resistors, and the result looks
quite clean and neat. I’d recommend also that Elecraft delete the
SMT option from the instructions. Took me about 30 mins to install the SMT
resistors, probably about half that time to install the through-hole ones. 73, Jim W8ZR _______________________________________________ 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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Re: K3 Audio Upgrade Mod
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Ron AC7AC wrote:
> > For those used to working with SMDs, piggy-backing the new SMDs on the > existing ones is actually easier than using the leaded parts, and some > don’t mind cutting a circuit trace to save some disassembly and time. > We wanted to give you and everyone else the option to chose. > Though they're not as much fun for me as through-hole parts, I had no particular trouble with the SMT resistors. I did wonder why they're piggybacked instead of replaced. One floated off and I had to put it back in. If they're just parallelled with the original 600 ohms, why not replace them? Leigh/WA5ZNU _______________________________________________ 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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Hi Ron and the group,
I use a homemade (by my friend K8DR) hold-down tool for soldering SMT parts, and I agree with Ron that they get easier to install with a little practice. However, I still believe that most hams would find easier the through-hole version of the audio upgrade mod, and since there's no electrical or mechanical disadvantage to that version, nor any likelihood of damaging the board, then I don't see any real benefit to offering the other version. True, a few experienced builders may be comfortable with SMT installation techniques: the problem, however, is the inexperienced builders who try it, get in over their head, and end up damaging their K3's circuit board. With respect to the RF choke part of the mod, it occurred to me that the problem with the "long" method is not that is too long (15 mins in my case), but that some builders might have trouble clearing the holes in the solder pads vacated by the original choke. I used a desoldering station to clear the holes, but many owners wouldn't have that or a "solder sucker." A way around the problem would be for Elecraft to provide two or three inches of solder wick with the kit, and then delete the option that requires cutting a trace on the circuit board. Once the pads are cleared, installing the new RF choke is very fast and easy, and one retains the pristine circuit board. Just a suggestion. 73, Jim W8ZR > -----Original Message----- > From: [hidden email] [mailto:elecraft- > [hidden email]] On Behalf Of Ron D'Eau Claire > Sent: Thursday, December 04, 2008 11:30 AM > To: 'Leigh L. Klotz, Jr WA5ZNU' > Cc: [hidden email] > Subject: RE: [Elecraft] K3 Audio Upgrade Mod > > Floated off? Did you heat both ends at the same time? > > I haven't checked the parts on that particular board, but many such parts > are attached to the board with a drop of adhesive before they're soldered. > > When mounting SMDs - piggyback or on a bare board, I tack one lead with a > slightly wet soldering iron tip while holding the part in place, just as > shown in the procedure. When I'm satisfied with the placement, I solder > the > other terminal(s). Then, if needed, I go back and touch up the first one. > > That way, at least one terminal is secure at all times to hold the part. > > Ron AC7AC > _______________________________________________ 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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Jim,
I'm with you in that most folks find it easier to work with leaded components on a SMT PC board -- until things start going bad. So, I'll take the counterpoint on this one... I learned the hard way that using leaded components on a surface mount pad/trace can lead to permanent PCB damage. For example, if making the K3 AF mod with the leaded resistors, one needs to avoid the temptation of moving the part after heat is applied and removed. Some folks (like your's truly), will be tempted to press the resistor against the PCB after soldering to ensure adaquate clearance from surrounding hardware. The surface area and bonding strength of the copper cladding relative to the glass board is extremely small. A small leaded component can take on the characteristics of a lever. A small amount of pressure on the parts yields pressures too great for the PCB pad. At some point, the breaking strength of the bonding is exceeded and the solder pad and/or trace lifts from the glass. When I first started working with SMT parts and began testing various leaded resistors of differing value, I did what I always do: I began to straighten the leaded component for visual aesthetics. Generally, this isn't a problem with through-hole boards. Why? The lead passing through the hole exhibits little, if any pressure on the surrounding pad or trace when the component is flexed. The pressure is built-up against the hole sides and not the surface of the PCB. By contrast, flexing of the leaded part on the surface of the PCB will almost always result in permanent PCB damage. Probably the moral of my story is that if leaded components are used on a SMT surface, do not flex the part thereafter! Paul, W9AC _______________________________________________ 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 |
Re: K3 Audio Upgrade Mod
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In reply to this post by Jim Garland
GA,
today I has same time for install K3-AF-mod (second part with R19 and R20). It was easy job. Yes, it's really worked! Now line-out are worked better! Here is plots "before" and "after" mod. Line-OUT before replaced R19&R20: http://forum.cqham.ru/download.php?id=33360 And AFTER: http://forum.cqham.ru/download.php?id=33361 And new R19&R20 on board :) : http://forum.cqham.ru/download.php?id=33362 Guys from Clifton-labs are clever! 73! Alex UR5LAM Dr. James C. Garland wrote: > The second part of the kit involves shunting two resistors with 51 ohm > resistors, and here also Elecraft gives two options: one is to solder > 1/8w through-hole resistors onto the IO board, and the other is to > solder two tiny SMT (surface mount ) resistors piggy-back onto existing > SMT resistors. The kit comes with both kinds of resistors. I elected to > do the SMT version of the mod, and here I’d recommend that owners opt > for the other method. I don’t see any advantage to doing the SMT > version. It takes a very steady hand, a very small-tipped soldering > iron, and very good eyesight to piggy-back the two SMT resistors into > the circuit, and I just don’t see the reason for the hassle. It would > take five minutes to install the through-hole resistors, and the result > looks quite clean and neat. I’d recommend also that Elecraft delete the > SMT option from the instructions. Took me about 30 mins to install the > SMT resistors, probably about half that time to install the through-hole > ones. > > > > 73, > > > > Jim W8ZR 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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ri
Priwet Alex! I believe you have made a mistake. The 51 ohm resistor should be placed ***ON TOP*** of the existing SMD resistors (i.e. in parallel with the existing resistors and NOT replacing them). Please read the instructions more carefully. 73, Bill W4ZV |
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In reply to this post by Alexander Ponomarenko-5
Please excuse my ignorance, but I have seen various references to the AF mod and I am not sure what it is supposed to do. Also, where is it located? I have the second receiver installed and I have a bad feeling that in order to get to it I'll have to tear things apart if I decide to do it. Any info would be appreciated.
Bruce-W8FU -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Alexander Ponomarenko Sent: Tuesday, December 09, 2008 4:51 PM To: undisclosed-recipients: Cc: [hidden email] Subject: Re: [Elecraft] K3 Audio Upgrade Mod GA, today I has same time for install K3-AF-mod (second part with R19 and R20). It was easy job. Yes, it's really worked! Now line-out are worked better! Here is plots "before" and "after" mod. Line-OUT before replaced R19&R20: http://forum.cqham.ru/download.php?id=33360 And AFTER: http://forum.cqham.ru/download.php?id=33361 And new R19&R20 on board :) : http://forum.cqham.ru/download.php?id=33362 Guys from Clifton-labs are clever! 73! Alex UR5LAM Dr. James C. Garland wrote: > The second part of the kit involves shunting two resistors with 51 ohm > resistors, and here also Elecraft gives two options: one is to solder > 1/8w through-hole resistors onto the IO board, and the other is to > solder two tiny SMT (surface mount ) resistors piggy-back onto existing > SMT resistors. The kit comes with both kinds of resistors. I elected to > do the SMT version of the mod, and here I’d recommend that owners opt > for the other method. I don’t see any advantage to doing the SMT > version. It takes a very steady hand, a very small-tipped soldering > iron, and very good eyesight to piggy-back the two SMT resistors into > the circuit, and I just don’t see the reason for the hassle. It would > take five minutes to install the through-hole resistors, and the result > looks quite clean and neat. I’d recommend also that Elecraft delete the > SMT option from the instructions. Took me about 30 mins to install the > SMT resistors, probably about half that time to install the through-hole > ones. > > > > 73, > > > > Jim W8ZR 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
Alex I believe I see what caused your misunderstanding. On the Main Mod Kits page, it states: "Line Out Change: KIO3 Main Board: R19/20 (input to line-out transformers) changed from 600 to 51 Ohms to increase line-out low distortion output levels." http://www.elecraft.com/K3/k3_app_notes.htm But on page 8 of the actual mod instructions it says: "Line Audio Output Modification This modification reduces the value of two resistors in the left and right channel line audio outputs on the KIO3 board by adding 51-ohm resistors in parallel with them. The existing resistors are surface mount types. Since the new resistors are wired in parallel with them, it is not necessary to remove the existing SMD units." http://www.elecraft.com/K3/mods/K3%20AF%20Stage%20Upgrade%20Instructions%20Rev%20A.pdf As has been noted by others before, I'm not sure why Elecraft did not suggest replacing the existing 600 ohm resistors with 47 ohms (parallel combination of 600 and 51). Perhaps they were concerned with the problem of potentially lifting the board traces when removing the 600 ohm resistors. The documentation on the main mods page (1st link above) needs to be corrected. 73, Bill W4ZV 73, Bill W4ZV |
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In reply to this post by Bill W4ZV
G'day,
I think placing the 51 ohm resistors on top of the existing SMD's was just for convenience. It makes little difference to the final result - 51 ohm vs. 45 - 49 ohm. Regards, Mike VP8NO ----- Original Message ----- From: "Bill W4ZV" <[hidden email]> To: <[hidden email]> Sent: Tuesday, December 09, 2008 7:37 PM Subject: Re: [Elecraft] K3 Audio Upgrade Mod | | ri | | Alexander Ponomarenko-5 wrote: | > | > GA, | > | > today I has same time for install K3-AF-mod (second part with R19 and | > R20). It was easy job. Yes, it's really worked! Now line-out are worked | > better! Here is plots "before" and "after" mod. | > | > Line-OUT before replaced R19&R20 | > | | Priwet Alex! | | I believe you have made a mistake. The 51 ohm resistor should be placed | ***ON TOP*** of the existing SMD resistors (i.e. in parallel with the | existing resistors and NOT replacing them). Please read the instructions | more carefully. | | 73, Bill W4ZV | | -- | View this message in context: http://n2.nabble.com/K3-Audio-Upgrade-Mod-tp1611843p1636256.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: 8.0.176 / Virus Database: 270.9.15/1839 - Release Date: 09/12/2008 09:59 _______________________________________________ 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 |
Re: K3 Audio Upgrade Mod
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Administrator
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Exactly.
Either way is OK. 73, Eric WA6HHQ Elecraft ---- Mike Harris wrote: > G'day, > > I think placing the 51 ohm resistors on top of the existing SMD's was just > for convenience. It makes little difference to the final result - 51 ohm > vs. 45 - 49 ohm. > > Regards, > > Mike VP8NO > > 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
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Re: K3 Audio Upgrade Mod
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In reply to this post by Mike Harris-9
GM,
yes of course Mike, I think any secondary school student can calculate it little difference. Besides, new resistors on top of old - it's not aesthetically. :) 73! Alex UR5LAM Mike Harris wrote: > G'day, > > I think placing the 51 ohm resistors on top of the existing SMD's was just > for convenience. It makes little difference to the final result - 51 ohm > vs. 45 - 49 ohm. > > Regards, > > Mike VP8NO > > | > | ri > | > | Alexander Ponomarenko-5 wrote: > | > > | > GA, > | > > | > today I has same time for install K3-AF-mod (second part with R19 and > | > R20). It was easy job. Yes, it's really worked! Now line-out are > worked > | > better! Here is plots "before" and "after" mod. > | > > | > Line-OUT before replaced R19&R20 > | > > | > | Priwet Alex! > | > | I believe you have made a mistake. The 51 ohm resistor should be placed > | ***ON TOP*** of the existing SMD resistors (i.e. in parallel with the > | existing resistors and NOT replacing them). Please read the > instructions > | more carefully. > | > | 73, Bill W4ZV > 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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