NORCAL QRP Club SMK-1 Instructions for use

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The NorCal QRP Club
SMK-1 Construction Manual
A Learning Tool For
Surface Mount Construction
Kit Building
By Dave Fifield, AD6A
Revision 0.1
April 2000
WARNING – DO NOT OPEN ANY OF THE PARTS BAGS YET!

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The SMK-1 Construction Manual
Introduction
Thank you for buying a NorCal QRP Club SMK-1 kit.
We’re sure you will enjoy learning/practicing surface
mount construction techniques by building the SMK-1.
As a bonus, when built, the SMK-1 is a fully working 40m
CW transceiver that you will be able to use on the air to
make contacts!
The idea to produce the SMK-1 kit came from Doug
Hendricks, KI6DS, who thought it would be a good idea
to have a cheap learning tool to get hams used to doing
surface mount construction, since that’s the way virtually
the whole electronic industry has gone and will inevitably
become the technique of necessity for ham kits in the
future.
All you will need to turn the SMK-1 into a fully working rig
is a case, some knobs, an antenna jack, a power jack, a
key jack and an earphone jack. Fortunately, the New
Jersey QRP Club has come to your rescue here! They
are supplying a custom designed PCB construction
case, knobs and connectors kit for the SMK-1 for only
$10 including shipping to anywhere. You can order one
from them by sending a check or money order for $10
made payable to George Heron to:
George Heron, N2APB
2419 Feather Mae Court
Forest Hill
MD 21050
USA
The SMK-1 contains over 80 components. Most of them
are surface mount parts. Some parts, like crystals,
trimcaps and pots, are either too expensive or not easily
obtained in surface mount packages so through hole
parts are used.
The surface mount parts used in the SMK-1 were
chosen to be large enough for most hams to be able to
handle them with a small pair of tweezers and solder
them in place using a fine-tip soldering iron. They are not
the smallest surface mount parts by a long way, but they
are small. I have personally built several kits now without
using a magnifier, but I do recommend you use one if
you have one! It will make life a lot easier for you,
especially if your eyesight isn’t quite what it used to be!
I recommend that you use a 1/16th inch or smaller
soldering iron tip, preferably temperature controlled, and
use 0.020” silver solder (although just about any solder
will do!). You will need a small pair of angled tweezers to
be able to handle the components with dexterity and
without damage.
Have fun building your SMK-1 kit – please let us all know
your progress and give us your comments/feedback on
the QRP-L email reflector.
General Description
The SMK-1 circuit is basically a modified Tuna Tin 2
transmitter integrated with a modified MRX-40 receiver. It
is a further modification of the modified TT2/MRX-40 that
I built for the indoor foxhunt at Pacificon 1999. All this is
fitted onto a small 2.475” x 2.25” PCB.
The transmitter consists basically of the two 2N2222A
transistor lineup of the original TT2 but with electronic
keying. A key-switched crystal oscillator that has some
degree of VXO feeds a medium power packaged version
of the 2N2222A as a final in class A mode. After
harmonic filtering, the result is about 350mW of fairly
clean transmit power on 7.040MHz (+/- a bit).
The RX front end uses the ubiquitous NE602
mixer/oscillator with a crystal VXO. The RX is a direct
conversion receiver, so you will hear both sidebands as
you tune through a station. The input stage of the NE602
has been biased a bit harder than normal by R1, a 22K
resistor (this resistor may need tweaking, if your receiver
is overdriven, increase the value of this resistor. Try 27K
or 39K). This gives the device more conversion gain.
The audio output of the NE602 direct conversion front
end goes through a FET switch that serves to mute the
audio to an acceptable sidetone level during TX and then
on to a standard LM386 audio power amplifier running
as much gain as it can.
The three controls on the front panel of the SMK-1 are
(left to right as you look at it) RF attenuation, RX tuning,
TX tuning. Operating the SMK-1 requires a little
knowledge of where you are receiving and transmitting –
there will be more on this in a later section of this
manual.

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Don’t Open The Parts Bags Yet – MUST
READ!
The parts bags have been loaded with components in
the exact order that you should solder them onto the
SMK-1 PCB. Since the components are tiny and many of
them have no markings on them at all, you must only
open one component compartment at a time! Solder all
the parts from that compartment onto the PCB before
opening the next compartment. It is imperative that you
do it this way, so you only have one value open at a
time. If you get the parts mixed up, tough bananas! You
have been warned!!
In a few of the kits shipped, one of the small orange
trimmer capacitors was put into the wrong compartment
– it was placed in with the 4.7uH inductor. If your kit is
one of these, when you get to the stage where you fit the
4.7uH inductor, save the orange trimcap on one side
until you get to the one at the bottom of the bag and
solder them in together then.
The through-hole parts and the transmit output
transformer are fitted last. Save the crystals, pots and
trimcaps till the end before you solder them in – it will
make life much easier.
Missing/Defective Parts
Due to the care and methodology put into the kitting
process, it is virtually impossible that any parts will be
missing from your SMK-1 Kit. However, due to the nature
of the small surface mount components in the kit, it is
very easy for you to lose parts and we anticipate that
there will be some loss! NorCal will only be able to
replace parts for $2. Send your lost parts requirements
with a check or money order for $2 made payable to
Doug Hendricks to:
Doug Hendricks, KI6DS
862 Frank Avenue
Dos Palos
CA 93620
USA
Please include an SASE for the parts.
Technical Support
For simple questions please use email to obtain
technical support from your fellow QRP’ers on the QRP-
L email reflector. To subscribe, send an email to
[e-mail] with the words “subscribe qrp-l <your
name> <your callsign>” on the first line of the email
body.
For more complex problems or issues or if you don’t
obtain satisfaction from the QRP-L email list, please
email me at [e-mail]
Surface Mount Soldering Technique
Use a fine soldering iron tip (1/16th inch or less) at about
700°F if possible. Use fine solder (0.020”), silver solder if
you can get it.
First, tin one PCB pad of the component you are going
to solder down. Don’t overdo the amount of solder – just
a slight bump of solder is enough – maybe a ¼” of solder
from your reel.
Next, pick up the component you are going to solder
down using your tweezers – carefully, lengthwise –
make sure you have it firmly, but not so firmly that it
goes “ping” and flies across the room! With your
soldering iron in one hand and the tweezers with the part
in the other, carefully place the part down onto the pads
in position – take care to line it up straight. Quickly dab
the wetted soldering iron onto the lead/pad that you
tinned previously to get it to stick nicely and sit flat.
Re-run the solder on this pad if you need to adjust the
position of the component. You must get it straight
and/or symmetrical across the pads at this time – once
you solder another pin, you will have no chance to re-
position it at all.
Once you are happy with its alignment on the pads (try
to get it right first time to minimize the possible heat
damage to the component), solder the other lead/s down
carefully. Go back and touch up the first lead if
necessary. That’s it – simple!
If you need to remove a part for any reason, the best
method is to use two soldering irons at once, one on
each end. If you only have one iron, add solder to both
sides of the part and heat them alternately until the part
comes away on the tip of the soldering iron. You will
need to use some solder wick to clean the PCB pads
before soldering down a new component. Surface mount
components that have been removed by this method are
usually good candidates for the trash can – try not to
reuse them unless you really have to.

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Getting Started With Bag #1
Turn Bag #1 around so that you are looking at it like this
with the “This Side Up” label in the bottom left hand
corner:
Item 6
13 x 0.1uF Item 1 3 x 82pF Item 2 1 x 100pF
Item 3
2 x 270pF Item 4 1 x 390pF Item 5 3 x 470pF
Item 22
1 x 10 Ohm Item 23 1 x 56 Ohm Item 24 1 x 100 Ohm
Item 25
1 x 220 Ohm Item 26 1 x 560 Ohm Item 27 2 x 1K
Item 28
2 x 2.2K Item 29 1 x 3.3K Item 30 1 x 4.7K
Item 31
1 x 5.6K Item 32 1 x 8.2K Item 33 5 x 10K
Bag #1
This Side Up Item 34 1 x 22K Item 335 1 x 47K
Using a sharp knife, cut open just the top left hand
compartment that contains Item #6, the thirteen 0.1uF
capacitors. Remove the capacitors from their containers
carefully, making sure that they do not fly off and get
lost!
Using the PCB legend on the board together with the
parts list and schematic, locate the 13 circuit references
for this component type and, one at a time, solder them
to the PCB.
When you have all 13 parts soldered down, move onto
the next compartment on the right that contains Item #1,
the three 82pF capacitors. Solder these parts to the
PCB.
Next do Item 2, Item 3, Item 4 …and so on down the bag
until you have fitted all the parts from Bag #1.
Continuing With Bag #2
Likewise, turn Bag #2 around so that you are looking at it
like this with the “This Side Up” label in the bottom left
hand corner:
Item 21
1 x PZT2222A Item 36 1 x 1M Item 37 1 x 2M
Item 18
2 x MMBF2222AL Item 19 1 x MMBF3906LT1 Item 20 1 x MMBFJ309LT1
Item 42
1 x SA602AD Item 43 1 x LM386 Item 12 5 x RLS4148
Item 44
1 x L78L06 Item 10 4 x SS16 Item 11 1 x GF1G
Item 13
1 x 1uH Item 14 1 x 4.7uH Item 15 1 x 12uH
Item 16
1 x 22uH Item 17 1 x 27uH Item 7 1 x 1uF
Bag #2
This Side Up Item 38 2 x 15-50pF Item 39 1 x FT37-43
Using the same technique as for Bag #1, solder the
parts to the PCB one compartment at a time. Some of
the parts in Bag #2 are polarized. Make sure you align
the bar ends of the diodes (items 12, 10 and 11) with the
bar marked on the PCB legend before soldering them
down. Item #7, the 1uF capacitor, has one side painted
black. This is the negative end and should be at the
opposite end from the + symbol that’s marked on the
PCB legend. Pay careful attention to the alignment of all
the polarized components or your kit will not work!
Identification of pin one for the 8 pin SOIC chips. Locate
the LM386 chip. You will note a small indentation or dot
in one corner. That is pin one. Also, note that the edge
of the IC is beveled on that size. That indicates the side
with pin 1. Use this information to find pin 1 on the
SA602 and the L78L06 chips. Be careful to place them
correctly.

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10uF & 100uF Capacitors
Next, locate the 10uF and 100uF capacitors, items 8 &
9. Solder them in place on the PCB paying careful
attention to the polarization. The black end of the
capacitor is negative (-) and should be at the opposite
end from the + symbol on the PCB legend.
TX Output Transformer (T1)
The output transformer is bifilar wound on the toroid. It
is quite easily done. Take the toroid and the two pieces
of red and green wire. Hold the two pieces of wire
parallel and wind 6 turns on the toroid, counting one turn
each time you go through the toroid. When you finish,
prepare the ends of the wire by trimming them about 1
inch long at first. Then burn the insulation off to the
edge of the core, use a piece of sandpaper to get all of
the insulation off and make sure that you have bright
copper wire showing. Tin each of the four leads. Now,
trim each of the leads so that they are ¼” long. Solder
the toroid on the pads, making sure that you solder the
red leads to pads 1 & 2 and the green leads to pads 3 &
4. You must do this correctly.
Crystals
The crystals are through hole parts. Place them in the
position indicated and solder them in. The cases must
be grounded and we have provided a place to do this.
Find a cutoff resistor lead (sorry, but there are no leaded
resistors here, but you should have one around). Solder
it in the hole next to the crystal. Bend the lead over the
crystal and solder it to the case of the crystal. Do this
quickly so as to not kill the crystal!!
Pots
Next, solder in the pots. Make sure that they are fully
seated to the board. This is important when you mount
your SMK-1 in its case (You did order the case and
connectors from the NJ QRP Club didn’t you??).
Finally, solder in the two trim caps. They are the little
square orange devices from Bag #2. When you solder
them in, make sure that you orient them exactly as
shown on the silkscreen of the board.
Wiring Up
Wiring the connectors is simple. Use small gauge
stranded hookup wire and connect the speaker jack, key
jack, power jack and antenna jack of your choice to the
back of the board.
Testing
Now it is time to test your efforts. Attach a dummy load.
Then apply 12 volts. Check for smoke, and hopefully
there won’t be any!! Replace the dummy load with an
antenna. We will start with the receiver section. Plug in
a set of headphones. Peak TC1 first to make sure that
you have 2 peaks. Go for highest noise level or signal.
Next peak TC2 for loudest signal. Next do the
transmitter, and that is the easy part. Plug in a key, and
transmit. Monitor on another receiver to make sure that
you are putting out power.
If you have problems, go to qrp-l, and post your problem.
There are literally thousands of fellow qrpers there who
will be more than happy to help with your problem.
Operation
Test units of the SMK-1 have tuned from about 7.035 to
7.039.7 on the receiver, and 7.0375 to 7.039 on the
transmitter. Thus the transmitter is the limiting factor on
making contacts. Use a transceiver to verify which side
of your signal that you want to tune the receiver to. You
will soon learn that a dc receiver has two sidebands, and
that you want to be on the correct one to make contacts.
Verify the correct sideband on a transceiver, and then
note which way that you tune the receiver in relation to
the tone, (whether it goes up or down in pitch as you
tune). Don’t worry, you will soon get the hang of it. If
you have questions, again, get on qrp-l, someone will be
there to assist you.
Again, the purpose of this kit was to assist you in
learning how to work with surface mount parts. We
believe that it succeeds, and for a very modest cost.
The transceiver does work, and it is capable of making
contacts. It is not an ICOM 706 by any means though.
We will be coming out with a full featured single band
surface mount kit later, this kit is just for training and we
hope that you have enjoyed it.

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Parts Placement