K3 12VDC OUT current modification

[Dennis L. Haarsager]

I just received the P3SVGA option for my P3 and see that it either needs a
separate 12VDC source with >= 700 mA current or installation of an included
current modification that raises the K3's 12VDC OUT capacity to 1 A.
Frankly, component level work on the K3 scares me, since neither my eyes
nor hands are as good as they once were and the last kit I built was an
HW-100 44 years ago.  I do have an ESD-safe soldering station and can
easily acquire some de-soldering tools, but can anyone who's done this can
give me some level of comfort that it's possible?  If it's risky, I'll dust
off an old 12V supply.

By the way, the $400 I spent on the HW-100 Heathkit by the CPI is the
equivalent of $2,590 in 2011 <http://www.measuringworth.com/uscompare/>, a
bit more than the cost of an assembled K3/100 today!

Dennis, N7DH
Hillsboro, VA
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[Fred Townsend]

Dennis I just finished doing that mod this morning getting ready for field
day. I'd like to tell you was easy but it's not. I'm a professional so I
have all the tools. It took me about three hours. I could have done it a lot
faster but I was extra careful not to drop hardware or leave soldering
debris. The problem is the board is designed for machine assembly and
soldering using a paste. The holes are small and almost padless. It took
several squirts of flux and two soldering irons to get the holes clean and
then the choke barely fit. It's a long way from your hot water 100. You have
cause for concern.
73
Fred, AE6QL

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Dennis L. Haarsager
Sent: Thursday, June 21, 2012 11:19 AM
To: [hidden email]
Subject: [Elecraft] K3 12VDC OUT current modification

I just received the P3SVGA option for my P3 and see that it either needs a
separate 12VDC source with >= 700 mA current or installation of an included
current modification that raises the K3's 12VDC OUT capacity to 1 A.
Frankly, component level work on the K3 scares me, since neither my eyes nor
hands are as good as they once were and the last kit I built was an
HW-100 44 years ago.  I do have an ESD-safe soldering station and can easily
acquire some de-soldering tools, but can anyone who's done this can give me
some level of comfort that it's possible?  If it's risky, I'll dust off an
old 12V supply.

By the way, the $400 I spent on the HW-100 Heathkit by the CPI is the
equivalent of $2,590 in 2011 <http://www.measuringworth.com/uscompare/>, a
bit more than the cost of an assembled K3/100 today!

Dennis, N7DH
Hillsboro, VA
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[ke9uw]

I use a Rigrunner 4010S power strip with Anderson Powerpole sockets. With the K3 plugged into the master slot, when the K3 is turned on the rest of the strip turns on. That way any accessories including the P3 come on with it. Good for any future accessories without issue as to supply current from that K3 source.

Chuck, KE9UW
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: [hidden email] [[hidden email]] on behalf of Dennis L. Haarsager [[hidden email]]
Sent: Thursday, June 21, 2012 1:19 PM
To: [hidden email]
Subject: [Elecraft] K3 12VDC OUT current modification

I just received the P3SVGA option for my P3 and see that it either needs a
separate 12VDC source with >= 700 mA current or installation of an included
current modification that raises the K3's 12VDC OUT capacity to 1 A.
Frankly, component level work on the K3 scares me, since neither my eyes
nor hands are as good as they once were and the last kit I built was an
HW-100 44 years ago.  I do have an ESD-safe soldering station and can
easily acquire some de-soldering tools, but can anyone who's done this can
give me some level of comfort that it's possible?  If it's risky, I'll dust
off an old 12V supply.

By the way, the $400 I spent on the HW-100 Heathkit by the CPI is the
equivalent of $2,590 in 2011 <http://www.measuringworth.com/uscompare/>, a
bit more than the cost of an assembled K3/100 today!

Dennis, N7DH
Hillsboro, VA
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[Bill Steffey NY9H]

>  I'd like to tell you was easy but it's not. I'm a professional so I
>have all the tools. It took me about three hours.
............
Hi Fred & all....
you must have been missing the one tool which made it easy ,,,,
my good ole Hakko solder sucker, which i bought before swapping all
the crystals in the K2 crystal filter.

I opened up the bottom , top & back Fan assembly.
 From the bottom, with the set upside down, let the Hakko do it magic
on the four pads, which dropped
the two parts on the table....  then inserted the two new
parts,,,resoldered,, lids closed.

bill  ny9h/3

   

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[Paul Saffren N6HZ]

I did the first one at my bench, and while I had a solder sucker available to me, I didn't use it.  I simply used some de-soldering braid.  First I removed the old F2 part, then completely filled the holes with new solder and finally used the solder-wick to remove all the solder.  Works like a champ.  Did this for the inductor as well.  The SMD part is a little trickier, and  I'm no spring chicken either.  The first thing you need is a really good magnifier, I prefer the goofy looking visor style.  To remove the old diode, I simply heat up one side with the iron and flick it up so it is only held by the other pad, then remove it completely.
I next use the solder-wick to completely clean the pads and then apply a very, very small amount of solder to one of the pads. Holding the new part with tweezers I place it on the pads and tap the soldering iron to the pad that has a little solder, then solder the other side and come back and clean up the first side.  The trick is to use a very small amount of solder.  If there is a blob on either end, you've used too much and can use some solder-wick to clean it up.

Ron did a great job on the instructions.  As he suggests, just take your time.  If a software engineer can do one, anyone can.

-Paul

[Fred Townsend]

Please see comments below.

 

-----Original Message-----
From: bill ny9h [mailto:[hidden email]]
Sent: Friday, June 22, 2012 8:33 AM
To: Fred Townsend; [hidden email]
Subject: Re: [Elecraft] K3 12VDC OUT current modification...tools

 

 

>  I'd like to tell you was easy but it's not. I'm a professional so I

>have all the tools. It took me about three hours.

............

Hi Fred & all....

you must have been missing the one tool which made it easy ,,,, my good ole
Hakko solder sucker, which i bought before swapping all the crystals in the
K2 crystal filter.

 

Bill I have numerous suckers including a thousand dollar desoldering
machine. The problem is suckers tend to generate solder balls. Like the
other gentleman that replied I used solder wick. I also took considerable
time to clean flux residues, ohmmeter the circuit, and inspect.  Yes the
documentation is excellent and no it's still not a simple task, particularly
if you have poor eyes, arthritis, or drink a lot of coffee which are the
questions I heard Dennis asking.

FT

 

 

 

I opened up the bottom , top & back Fan assembly.

>From the bottom, with the set upside down, let the Hakko do it magic on the
four pads, which dropped the two parts on the table....  then inserted the
two new parts,,,resoldered,, lids closed.

 

bill  ny9h/3

 

   

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[Don Wilhelm-4]

Fred,

I put one in a friend's K3, and it only took about an hour.  Most of
that time was in removing the PA assembly and putting it back.

The components were removed by alternately heating the ends (one at a
time) until they cold be flicked off the solder pads.

I have decent mobility and good solder/de-solder skills.  So if you have
problems with arthritis and poor eyes and drink a lot of coffee, it may
be wise to let someone else do it for you.  Do you have any capable hams
nearby that might give you a hand.

73,
Don W3FPR

On 6/22/2012 2:47 PM, Fred Townsend wrote:

> Please see comments below.
>
>  
>
> -----Original Message-----
> From: bill ny9h [mailto:[hidden email]]
> Sent: Friday, June 22, 2012 8:33 AM
> To: Fred Townsend; [hidden email]
> Subject: Re: [Elecraft] K3 12VDC OUT current modification...tools
>
>  
>
>  
>
>>   I'd like to tell you was easy but it's not. I'm a professional so I
>> have all the tools. It took me about three hours.
> ............
>
> Hi Fred & all....
>
> you must have been missing the one tool which made it easy ,,,, my good ole
> Hakko solder sucker, which i bought before swapping all the crystals in the
> K2 crystal filter.
>
>  
>
> Bill I have numerous suckers including a thousand dollar desoldering
> machine. The problem is suckers tend to generate solder balls. Like the
> other gentleman that replied I used solder wick. I also took considerable
> time to clean flux residues, ohmmeter the circuit, and inspect.  Yes the
> documentation is excellent and no it's still not a simple task, particularly
> if you have poor eyes, arthritis, or drink a lot of coffee which are the
> questions I heard Dennis asking.
>
> FT
>
>  
>
>  
>
>  
>
> I opened up the bottom , top & back Fan assembly.
>
> >From the bottom, with the set upside down, let the Hakko do it magic on the
> four pads, which dropped the two parts on the table....  then inserted the
> two new parts,,,resoldered,, lids closed.
>
>  
>
> bill  ny9h/3
>
>  
>
>    
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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