Rex, W1REX puts out a great Kit of the Month over at http://www.qrpme.com/. The first was the Pocket Electronics Lab which I built in an easy evening.

So on Saturday, December 1st, 2007, I began assembling my ATS-3B QRP Transceiver. I had decided to start with the six filter boards since they each had three toroids and only one SMT component. I figured I’d save the fun part for last (I have come to really enjoy/prefer SMT) 🙂

This write-up is to record my initial thoughts and show the process for those considering construction of an ATS-3B.

	I use my multimeter to check the surface temperature of my electric skillet. I have found that bringing this warming surface (with the pc board already on the surface) close to 200 degrees Fahrenheit makes the amount of time I need to wave the hot air tool over the components quite short; on the order of maybe ten or twenty seconds.
	I found these Craft Mates bead storage containers at Michael’s Crafts. They keep the contents inside each of the compartments. You needn’t worry about your SMT components getting mixed in these. You can see what’s inside without opening. There’s a spring-loaded latch lock which keep the compartments closed.
	Five of the six band filter boards have an SMT resistor on the side opposite the toroids. I did all five at once time using Cash Olsen’s Hot Air Method. I use the Rival 12″X12″ electric skillet for the warm-up surface. I also use the skillet as my assembly tray because it has nice raised sides.
	This whole process took less than ten minutes. Of course after the solder paste is melted, you should turn off the heat on the warming surface and let it cool down slowly.
	Initially the paste will appear a dull grey but will turn very silver and sometimes give up a tiny puff of smoke.
	After the process is complete and the board is cooled-down, you can pick up the pc board and inspect each connection. I use a combination of my lighted magnifier plus a jeweler’s visor to get a real good look at my work.
	This is how I wind my toroids. There’s a zen to it actually. Using a chopstick in a nice, place the toroid over the tip of the chopstick and the wire, pull the wire taut, and repeat. My hands stay free and without cramps. I can take a break and go grab another beer. 🙂
	Here’s a finished toroid. Can you guess which one?
	When winding toroids, I usually have some music on or something to keep me slightly distracted. This is not a conducive environment for keeping track of windings on a toroid. So I get it really close, and then I scan the toroid my computer and zoom in using any decent graphics program (I use the free Fast Stone image viewer) and count the windings without any pain. I’m usually within one or two windings anyway. Even if you use the pencil+hashmark, it still pays to check your work this way.
	The toroids mounted on a band filter board

The through-hole components were quite easy. I’ve done one board per night in less than an hour each. Two more to go (one tonight and one tomorrow night) and then I begin on the main ATS-3B circuit board.

And as I mentioned last time, our dogs, Honey and Shaggy, had decided to show their superdog wrestling skills right at my feet:

Stay Tuned and 72/73!
Jack, K6JEB

(click on images for full size)

OK, tonight I used the Cash Olsen’s SMT Hot Air Method (SMarT HAMethod) to assemble a NorCal Tuner Upper SMT kit for 30 meters. This was my first foray into using solder paste and a hot air tool (instead of the normal soldering iron and spool of solder) to quickly mount the many tiny parts. Using this method, even the first time, I believe I had quite a success and did it in a fraction of the time. Each solder joint is clean and even. The components really do center (mostly) on their pads.

As a pre-warming surface, I picked-up a 12″X12″ Rival electric skillet from Target for $24.99. I could have spent less but I wanted a surface that was large enough for most any circuit boards and have raised walls to safeguard against parts getting lost. The skillet has a WARM setting which sits at a nice and even 200 degrees Fahrenheit at the surface. My Multimeter has a temperature probe that is accurate enough for this application. I actually put the SMT parts on the board right in the skillet (before I turn on the heat silly!). This skillet also has a cover which I can put on when I need to take a break (you know, like going to get another cold beer hi hi).

It was a simple matter of dropping a small dollop of solder paste, which I ordered from Electronic Research Group. The Kester paste comes in larger quantities but it is WAY more than most of us need in the shack and it does have a shelf life. The paste needs to be stored in the fridge. I hardly noticed any difference between the amount I had when I started and how much was left in the syringe afterward. So there should be enough for plenty projects in each of these syringes.

Having never done this before, I wasn’t sure how long to hold the heat tool on any one spot. So I just ran quick small circles across the surface of the board. About three minutes after I began, I noticed the paste turn from its dull grey to a nice shiny silvery sheen. You’ll see the components pull toward the center of the pads as the paste melts. The following images show, from left to right: 1) SMT components mounted on the circuit board mushed onto a dollop of solder paste 2) first round on the board 3) second round to get the two less-than perfect points 4) final results:

The images above show the circuit board in the tin.

Earlier this year, I built this same kit for 20 meters. It took me the better part of a morning to solder each of those parts to their pads. There are just a couple through-hole parts in this kit. The main time sink is winding the toroids. I suggest using a chopstick in a vice to hold your toroid between each winding. The results were nowhere as neat and clean as what I get using the SMT Hot Air Method. Never mind the fact that this took less than half an hour to mount the SMT parts, I’m going to start calling this the “SMarT HAMethod”. 🙂

SMarT HAM above, Done By Hand below.

Here’s a video I found on YouTube that shows how the pros do it: