[Elecraft] k2 control board r18, r19

[Ron D'Eau Claire]

Jon, VE8JJ, wrote:

I just want to confirm the assembly instructions:
R18 and R19 are basically resistors with value of 0 (zero) ohms. So you
solder in a piece of wire for each of them. Then if and when you are ready
to install KAF2, you desolder and remove the two wires at R18 and R19.

With my trusty Hakko 936 at the ready, soldering is a joy. Desoldering, on
the other hand, is something I can't seem to do even if my life depended on
it.

I know what conventional wisdom has to say about silver solder, but that's
what I am using because it just seems so much easier to solder with. Plus,
like writing a math test with a pen, it's a terrific incentive to get things
right the first time.

The downside is, with my skills, or lack of, if any desoldering has to be
done, the patient will surely die.
Any thoughts on a "solderless" solution to R18 and R19?

------------------------------------------------------------

Hello Jon:

Because R18 and R19 are jumpers, they are easy to remove: just cut them. If
you want to clear those pads, you can simply heat the pads while holding the
cut jumper and pull *gently*. When the solder melts, it'll slip right out. 

There's nothing inherently "better" about using silver solder in the K2. It
is needed in certain very critical RF applications where very high RF
currents are flowing at very high frequencies. For example, in some 900 MHz
repeater equipment that I've serviced the manufacturer required that silver
solder be used in its power amplifier circuits. 

Elecraft backed off of suggesting silver solder because it offers no
technical or performance advantage and is slightly harder to remove. Still,
you shouldn't have any trouble if you use a good quality solder-sucker like
Elecraft recommends. Solder wick will work FB too, when done properly. What
most ops miss is that you *must* raise the temperature of your iron when
using wick. That wick soaks up a lot of heat. I crank up my soldering iron
temperature to 800 to 850 degrees F and then use narrow wick and work at the
*end* of the wick (keep cutting away the used segments) to minimize the
amount copper there to absorb heat from the iron. Done that way, sometimes
the wick is faster and easier for me than pulling out the solder-sucker. 

Board traces get lifted when too much total heat energy is put onto them,
not by temperature alone. An iron or wick that is just barely hot enough to
work so it must be left in place a l-o-n-g time will do far, far more damage
than a hotter iron or wick left on there a short time.

By the way, I *never* took a math test using a fountain pen! I was the guy
sitting there in a cloud of eraser dust with a pocket full of pencils. 

You have courage Jon, and I'm sure that your pride in the work and the
performance of your K2 will reward you in the end! 

Ron AC7AC