[Elecraft] K3 VFO Tuning noise reduction

[Ron D'Eau Claire]

I did the latest illustration for Wayne and I found it very easy to solder
to the vias shown. 

I will admit that my actual procedure was slightly different from what Wayne
wrote. Since Wayne had worked out exactly how the parts fit on the board, it
was not necessary to assemble the diode/resistor pairs before mounting them
on the board. 

I mounted the diode in the proper pad first, bending and cutting  the lead
so it just rested in the via in the position shown, then soldering.

Then I mounted the resistor in the same way.

Now both the diode and resistor are held securely since each has a lead
soldered to the proper via.  

Finally, I positioned the parts and formed and trimmed the leads so they
touched where the resistor and diode connect together, then soldered the
junction. 

Repeat for the second component pair. 

Some people complained that the vias were filled with solder. One set of
vias on my board were the same, but they are *very* easy to clear even
without a power solder sucker using a bit of solder braid. 

The "trick" to using solder braid is FLUX and adequate heat. Few braids -
even the expensive variety - have adequate flux to do the job right. It's
almost impossible to introduce more flux by adding solder; the flux burns
away too quickly. 

I keep a bottle of rosin flux on my bench. As it happens I have GC
Electronics 10-4202: a 2 oz bottle with a brush. See www.gcelectronics.com
for their products, but any *rosin* flux is safe and good to use.

Also, remember that the braid is a good "heat sink" requiring you to raise
your iron temperature a bit to put adequate heat on the side against the via
you want to clear.  That's where having narrow braid (I use 2mm) is good
because it minimizes the loss of heat. Even so, I set my iron for 750 to 800
F (400-425C). 

In just a few seconds the vias looked just like what you see on the left
side of the illustration at "pad locations" (you can see that they are
tinned while the other vias are not). If you use a 1/4 watt resistor the
lead will be a snug fit through the via. Once the via is open you can use a
probe to open it up a little farther if needed so the end of the lead will
slip through. 

The rosin flux is completely safe. It only becomes corrosive at temperatures
that will melt solder. If your board ever gets hot enough for all the solder
to melt, the idea of flux becoming active will be the least of your
concerns, Hi! If some archeologist finds my K3 RF board at some distant
future date, those solder joints will be as sound as they are today. 

Ron AC7AC




-----Original Message-----

No, you still have the diode and resistor in series.

However as the each of the vias go to pads 15 & 20 of the 
connectors respectively, soldering to the pads is an alternative 
to soldering to the vias.

You can check the continuity with a VOM just to make sure.

Hope that's OK ?

73
Stewart G3RXQ