I'm sure this has been beaten to death already, but I missed it. Is there a
very small SMT QRP kit or design somewhere, maybe on equal to the NorCal 40
or better? I'm aware of the SMK-1. Am looking for the smallest possible rig
with 5W and good RX. Would it be reasonable to repackage, say, the NorCal 40
with all surface mount parts? Certainly someone must have already tried
this. What results did you find?

By way of introduction, I am N9XI. My main rig is a K2, an early first run
kit from '99. I think I understand the apparent trepidation surrounding SMT,
although I believe it's unfounded and not entirely rational. After all this
time, the dearth of very small rigs based on the smaller parts is
surprising. (Yell if a quick primer on SMT construction will be useful. I
reflow boards in a skillet on the kitchen range.)

Mike:

There have been a few very interesting SMT transceiver kits with
limited production runs, including KD1JV's ATS series. Nothing much
about them on his website now.

http://kd1jv.qrpradio.com/

There's quite a bit of info on the ATS-3 at
http://www.ae5x.com/ats3.html .

Another recent one is the NorCal 2030 (supposed to have a pretty good
RX), see

http://www.norcalqrp.org/nc2030.htm

These limited edition kits area usually announced on the QRP-L email
reflector.

The MFJ "QRP-Cub" transceivers are partially SMT and have 2 W output.
But the kit version has all the SMT parts already mounted so you miss
out on the kitchen fun !

73,
Steve VE3SMA

wrote in message
oups.com...
Mike:

There have been a few very interesting SMT transceiver kits with
limited production runs, including KD1JV's ATS series. Nothing much
about them on his website now.

http://kd1jv.qrpradio.com/

There's quite a bit of info on the ATS-3 at
http://www.ae5x.com/ats3.html .

Another recent one is the NorCal 2030 (supposed to have a pretty good
RX), see

http://www.norcalqrp.org/nc2030.htm

Thanks for the links. The ATS3 looks promising, as do the DDS and SDR
directions. I'm pleased to find the fresh ideas making their way along.
Seeing the gulf between the old and the new, though, it makes you wonder
(yet again) where HF operating will be in another ten or twenty years. I
have half a mind to hibernate another year or so, and see where the "kids"
take us.

Mike Young wrote:

I'm sure this has been beaten to death already, but I missed it. Is
there a very small SMT QRP kit or design somewhere, maybe on equal to
the NorCal 40 or better? I'm aware of the SMK-1. Am looking for the
smallest possible rig with 5W and good RX. Would it be reasonable to
repackage, say, the NorCal 40 with all surface mount parts? Certainly
someone must have already tried this. What results did you find?

By way of introduction, I am N9XI. My main rig is a K2, an early first
run kit from '99. I think I understand the apparent trepidation
surrounding SMT, although I believe it's unfounded and not entirely
rational. After all this time, the dearth of very small rigs based on
the smaller parts is surprising. (Yell if a quick primer on SMT
construction will be useful. I reflow boards in a skillet on the kitchen
range.)

I am aware of toaster oven reflow, but I haven't seen skillet reflow.
If you have the time and inclination to prepare a little web site --
particularly if you could do pictures -- that would be cool.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim Wescott wrote:
Mike Young wrote:
(Yell if a quick primer on SMT
construction will be useful. I reflow boards in a skillet on the kitchen
range.)

I am aware of toaster oven reflow, but I haven't seen skillet reflow.
If you have the time and inclination to prepare a little web site --
particularly if you could do pictures -- that would be cool.

What's to figure out? A little olive oil, fresh-ground pepper...

Tune in Thursday when Emeril demonstrates reflow in a boil-in bag, with pesto.

--
If John McCain gets the 2008 Republican Presidential nomination,
my vote for President will be a write-in for Jiang Zemin.

"clifto" wrote in message
...
Tim Wescott wrote:
Mike Young wrote:
(Yell if a quick primer on SMT
construction will be useful. I reflow boards in a skillet on the kitchen
range.)

I am aware of toaster oven reflow, but I haven't seen skillet reflow.
If you have the time and inclination to prepare a little web site --
particularly if you could do pictures -- that would be cool.

What's to figure out? A little olive oil, fresh-ground pepper...

Tune in Thursday when Emeril demonstrates reflow in a boil-in bag, with
pesto.

That's not too far off. We're all somewhat mislead by the assumed
complexity. After all that we've read and thought, it's not easy to accept
on faith that reflowing doesn't have to require carefully controlled
equipment and expensive stencils. For now, consider only that hand soldering
is much more stressful to the parts than almost any other (mis)treatment.
Uneven heating; uncertain temperature rise; solder bridging and subsequent
rework and more heat stress; ... on and on. On that basis alone, stir-frying
is already a huge improvement. At its best, it isn't very far from a more
stringently controlled process.

A few pictures of it working will help make the point. I had every intention
at the onset of taking a few, and plotting temperatures taken with an IR
thermometer. After doing the first board, though, the whole process seemed
as obvious as noting that a rock will indeed drive nails. Or something like
that. Bear with me.

The temperature profile is likely the major concern in your mind. Here's an
example of a profile: http://www.stencilsunlimited.com/solder_products.php.
Click on the link for "SynTECH Technical Data Sheet". The profile is on page
2. (Incidentally, their prices are among the lowest I found for small
quantities. Less than $25 for a 35g syringe shipped. I use their 63/37
paste.)

There are two important control points: flux activation at 140^C, and reflow
at 220^C. Flux activation is easily recognizable by the gray crud that forms
on the paste. Reflow is also obvious from visual cues: the paste turns
silvery and looks like molten solder. All that's needed now is to control
the time.

Medium flame on my kitchen range is just about right for my thick bottomed
aluminum skillet. Flux activation "happens" in a little less than 2
minutes. Reflow starts about 2 minutes later. When the last bit of paste
turns silvery, cover the skillet, count to ten slowly, and then turn off the
flame. Let it cool undisturbed.

The rest of it is putting on the paste and populating the board. You don't
need a stencil to do that. Just draw a neat bead along the pads. The parts
center themselves when it reflows. Compare that to the contortions of
holding an SOT23 in place to solder by hand.

There is a difference in how you plan your work. Since you can reflow only
once without special pastes and finer control, everything has to go on in
the 6 hours the paste remains workable. The NorCal 2030 probably shouldn't
be your first project.

Anyway, stir frying works well and easily with very few critical details.
Try it on a scrap board first to "calibrate" the stove. Within reason, a
little too hot is better than not hot enough, and a little too much paste is
better than not enough.

Mike Young wrote:
"clifto" wrote in message
...

Tim Wescott wrote:

Mike Young wrote:

(Yell if a quick primer on SMT
construction will be useful. I reflow boards in a skillet on the
kitchen
range.)


I am aware of toaster oven reflow, but I haven't seen skillet reflow.
If you have the time and inclination to prepare a little web site --
particularly if you could do pictures -- that would be cool.


What's to figure out? A little olive oil, fresh-ground pepper...

Tune in Thursday when Emeril demonstrates reflow in a boil-in bag,
with pesto.


That's not too far off. We're all somewhat mislead by the assumed
complexity. After all that we've read and thought, it's not easy to
accept on faith that reflowing doesn't have to require carefully
controlled equipment and expensive stencils. For now, consider only that
hand soldering is much more stressful to the parts than almost any other
(mis)treatment. Uneven heating; uncertain temperature rise; solder
bridging and subsequent rework and more heat stress; ... on and on. On
that basis alone, stir-frying is already a huge improvement. At its
best, it isn't very far from a more stringently controlled process.

A few pictures of it working will help make the point. I had every
intention at the onset of taking a few, and plotting temperatures taken
with an IR thermometer. After doing the first board, though, the whole
process seemed as obvious as noting that a rock will indeed drive nails.
Or something like that. Bear with me.

The temperature profile is likely the major concern in your mind. Here's
an example of a profile:
http://www.stencilsunlimited.com/solder_products.php. Click on the link
for "SynTECH Technical Data Sheet". The profile is on page 2.
(Incidentally, their prices are among the lowest I found for small
quantities. Less than $25 for a 35g syringe shipped. I use their 63/37
paste.)

There are two important control points: flux activation at 140^C, and
reflow at 220^C. Flux activation is easily recognizable by the gray crud
that forms on the paste. Reflow is also obvious from visual cues: the
paste turns silvery and looks like molten solder. All that's needed now
is to control the time.

Medium flame on my kitchen range is just about right for my thick
bottomed aluminum skillet. Flux activation "happens" in a little less
than 2 minutes. Reflow starts about 2 minutes later. When the last bit
of paste turns silvery, cover the skillet, count to ten slowly, and then
turn off the flame. Let it cool undisturbed.

The rest of it is putting on the paste and populating the board. You
don't need a stencil to do that. Just draw a neat bead along the pads.
The parts center themselves when it reflows. Compare that to the
contortions of holding an SOT23 in place to solder by hand.

There is a difference in how you plan your work. Since you can reflow
only once without special pastes and finer control, everything has to go
on in the 6 hours the paste remains workable. The NorCal 2030 probably
shouldn't be your first project.

Anyway, stir frying works well and easily with very few critical
details. Try it on a scrap board first to "calibrate" the stove. Within
reason, a little too hot is better than not hot enough, and a little too
much paste is better than not enough.

Do you just sit the board on the bottom of the pan, or do you space it
up? Can you do double-sided boards? What else didn't I ask?

I've seen the web sites showing how to do toaster-oven reflow -- have
you tried that?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
Do you just sit the board on the bottom of the pan, or do you space it up?
Can you do double-sided boards?

There's just the slightest curve on the bottom of the skillet so it sits on
its corners. I don't believe this is critical. Direct contact on the face
will probably work just as well.

Components on the top-side only. You'll need to use a different paste if you
need to reflow top and bottom, and definitely need tighter control on the
temperature for the second side. An uncontrolled skillet won't do for that.
Use a tin/silver paste for the first side. Its higher reflow temperature
will allow you to reflow tin/lead on the second side. You'll want to use
stand-offs in a properly controlled oven for that.

What else didn't I ask?

Hot air is an alternative. I use a Weller Portasol with hot air nozzle for
small rework. I hear of others replacing the rubber bulb on a Radio Shack
desoldering iron with an aquarium pump. It takes longer to build a board,
but might suit the pace of a homebrewer better.

I've seen the web sites showing how to do toaster-oven reflow -- have you
tried that?

I haven't tried using a toaster oven. The concepts remain the same, however.
There might be a difference between heating with IR elements and heating the
board more or less directly.