Vectronics VEC-121K User Manual

IMPORTANT WARRANTY INFORMATION! PLEASE READ

Return Policy on Kits When Not Purchased Directly From Vectronics: Before continuing
any further with your VEC kit check with your Dealer about their return policy. If your Dealer
allows returns, your kit must be returned before you begin construction.

Return Policy on Kits When Purchased Directly From Vectronics: Your VEC kit may be
returned to the factory in its pre-assembled condition only. The reason for this stipulation is,
once you begin i nsta lli ng a nd sol deri ng pa rt s, you essenti al ly tak e over the rol e of the devic e's
manufacturer . From this point on, neither Vect ronics nor its dea lers can reas onably be held
accountab le for the qua lity or the outcome of your work. Because of this, Vectronics cannot
accept return of any kit-in-progress or completed work as a warranty item for any reason
whatsoever. If you are a new or inexperienced kit b uilder, we urge you to read the manual
carefully a nd determine whether or not you're r eady to tak e on the job. If you wish to c hange
your mind and return your ki t, you may--b ut you must do i t before you begin c ons tr uc ti on, a nd
within ten (10) working days of the time it arrives.

Vectronics Warrants: Your kit contains each item specified in the parts list.
Missing Parts: If you determine, during your pre-construction inventory, that any part is

missing, please contact Vectronics and we'll send the missing item to you free of charge.
However, before you contact Vect ronic s, please look carefully to c onf ir m you haven't misr ea d
the marking on one of the other items provided with the kit. Also, make certain an alternative
part hasn't been substituted for the item you're missing. If a specific part is no longer
available, or if Engineering has determined that an alternative component is more suitable,
Vectronics reserves the right to make substitutions at any time. In most cases, these changes
will be clearly noted in an addendum to the manual.

Defective Parts: Today's electronic parts are physically and electrically resilient, and
defective components a re r a re. However, if you disc over a n it em duri ng your pr e- c onst r uct i on
inventory that's obviously broken or unserviceable, we'll replace it. Just return the part to
Vectronics at the address below accompanied with an explanation. Upon receipt, we'll test it.
If it's defec tive and appear s unused, we'll ship you a new one right away at no charge.

Missing or Defective Parts After You Begin Assembly: Parts and materials lost or
damaged after construction begins are not covered under the terms of this warranty. However,
most parts supplied with VEC kits are relatively inexpensive and Vectronics can replace them
for a reasonable charge. Simply contact the factory with a complete description. We'll
process your order quickly and get you back on trac k.

Factory Repair After You Begin Assembly: Kits-in progress and completed kits are
specifically excluded from coverage by the Vectronics warranty. However, as a service to

customers, tec hnicia ns ar e availa ble t o evaluate a nd repai r malf unctioni ng kits for a minimum
service fee of $18.00 (½ hour rate) plus $7.00 shipping and handling (prices subject to
change). To qualify for repair service, your kit must be fully completed, unmodified, and the
printed circuit board assembled using rosin-core solder. In the event your repair will require
more than an hour to fi x (or $36.00, subject to change), our technicians will contact you in
advance by telephone b efore p erforming t he work. Def ective unit s should b e shipp ed prep aid
to:

Vectronics
1007 HWY 25 South
Starkville, MS 39759

When shipping, pack your kit well and include the minimum payment plus shipping and
handling charges ($25.00 total). No work can be performed without pre-payment. Also,
provide a valid UPS return address a nd a day time phone number where you may be reac hed.

VEC-121K Owner's Manual Crystal Radio Set Kit

INTRODUCTION

Relive those bygone days of radio--a time almost 90 years ago, when early radio
pioneers experimented with crystal radio receivers! Wind your own “inductor”
coil, wire up the earliest radio circuit; and, there’s no soldering needed!
Everything is assembled on a pine “breadboard”, just like great, great granddad
did when he was a youngster. Lear n ab o ut b a sic r a di o theo r y. Put up an antenna
(wire included), connect a ground, and experience the magic of a radio that
needs no power. A special high-sensitivity earphone allows you to hear AM
Broadcast signals from many miles away; this little baby really performs. The
VEC-121K is a fascinating project for youngsters of all ages!

The VEC-121K features a modern “fixed detector”, eliminating the need for
frequent and frustrating catwhisker adjustments. A large, Hi-Q antenna coil, and
a modern miniature Hi-Q tuning capacitor, are used for best sensitivity and
selectivity. The high-impedance parallel-resonant tuning circuit allows a short
receiving antenna to deliver maximum signal to the set.

TOOLS AND SUPPLIES

Having the right too l to do a job always makes things go be tter. There is no
soldering required, and only a few basic hand tools are needed to assemble your
VEC-121K crystal radio set.

This is a list of the tools you will need:

SAFETY EYEGLASSES or GOGGLES!

parts is a lot of fun, but please, safety first! Your local hardware store carries
inexpensive safe ty goggles. Befo re you are go ing to be cutting or wor king with
wires, hammering, handling any chemicals, or using any tools, put on your
safety eye wear first!

1.

Phillips screwdriver.

kit, and we will use this tool when it is time to mount parts on the wood
board. Try to find a screwdriver with a shaft (the distance between the tip
and start of the handle) that is at least 3” long.

2.

Long-nose pliers.

by electricians. The long slender nose makes it easy to hold or bend a wire
that is being worked on.

3.

Wire cutters.

long-nose pliers styles feature built-in wire cutters. Wire cutters are
sometimes called “nippy cutters” or “diagonal wire cutters”—depending on
how they’re made.

These special pliers have sharp cutters to cut wires. Some

There are eight Phillips head screws included in the

These pliers have a long and tapered nose and are used

Working with wires, tools and radio

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VEC-121K Owner's Manual Crystal Radio Set Kit

4.

Ruler or tape measure.

5.

Small penknife.

A penknife, or small E xacto

A small 12” ruler or flexible tape measure will do.

TM

knife, is needed to scrape
off wire insulati o n. If you a r en’t o l d e no ugh to use a knife , a small se ct io n o f
sandpaper will do.

6.

Small Hammer.

It will be used with a finishing nail to mark where the

screw holes are placed on the pine board.

7.

Small-Screwdriver or Hex-Tool

. Size to fit the set screw in the tuning

knob--depending on which type of knob is supplied with your kit.

Radio Shack carries many inexpensive small hand tools for electronics work.
Here are some items that will come handy:

1.

Masking tape.

2.

Cyanoacrylate adhesive.

is sold as “Super Glue

This is the fancy name for contact cement, which

TM

” or “Crazy GlueTM ”. You’ll use the contact cement
to hold the coil windings in place. These adhesives are very strong, and can
instantly glue your fingers t ogether i f you are not c areful! If you ar e not old
enough to work with co ntact cements, have someone who is o lder help you
when gluing is directed in the instructions. The glues used to assemble
plastic model airplanes are safer to work with and may also be used instead
of super glue. However, they will require a longer time to dry. Always have
an adult advise and supervise your use of any chemicals!

WOODWORKING AND FINISHING (OPTIONAL)

Perhaps this is your first kit building experience, or your first homemade
receiver project. If so, your VEC-121K crystal receiver will be a source of pride
for many years to come. Before assembling this kit, you might wish to consider
sanding and staining the pine board—this will bring out the beauty of the wood,
and make your project look as if it was done by an “old pro”. Many early radios
were built in what was called “breadboard” fashion. The radio parts were laid
out on a small section of wood board.

Early radio parts were very expensive, even a simple crystal radio set could cost
a week’s pay! Most experimenters had to improvise. Often an old breadboard
(used to roll out bread dough) was used as a base to mount radio parts. If you
were well-to-do, your “breadboard” was probably a fine piece of mahogany or
walnut board!

Sanding:

Before applying a stain finish, carefully sand the pine board using 200
grit sandpaper. When sanding the surfaces, always sand in the direction of the
grain to avoid scratching the wood. The two board edges that expose the end

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VEC-121K Owner's Manual Crystal Radio Set Kit

grains of the wood will be rather rough to the touch, and will require some extra
sanding to produce a smooth even surface. You may have to use a 150 grit in
the beginning on the end grains. Sanding is best done outdoors. Wear a
disposable paper dust mask while sanding.

Finishing:

Your local hardware store stocks small cans of woodworker stains.
Either a walnut or mahogany wood stain finish is a good choice. Both oil-based
and water-based stains are availab le. We suggest using a water-ba sed stain for
this project—it is easier to work with and easier to clean up afterwards. You
will need a clean cloth, or staining cloth, to apply the stain. Follow the
manufacturer’s directions very carefully, and read the safety information on the
label. Use dispo sable la tex gloves when hand ling stain. If you’re too young to
safely work with wood stains, ask an adult for assistance with this portion of the
project. Always handle any chemicals with great care!

Important Note:

begin. Before attaching the tuning capacitor with the double-sided adhesive
tape, the board should be allowed to dry for a few days. This will allow the stain
to fully cure, or dry, so it does not interfere with the tape adhesive.

Once the stain is dry to the touch, the assembly work may

BEFORE YOU START BUILDING

Your work area:

what you are doing. At times we will need to set items aside to allow glue to
dry; or you will need to stop working on your project for other activities. Your
work area should be in a place where your project does not interfere with others.

Keep your work area clean and free of clutter. Kit parts should be kept in the
box until you need to use them. When you are finished for the day, return the
tools to their proper place. Put unused kit parts back in the box so you will not
lose them. I f you are old eno ugh to use glues and wood stains, you may have
younger brothers and sisters who aren’t! Keep chemicals out of the reach of
younger children.

Use a good workbench with good lighting so you can see

Following directions:

Kits are built in “steps”. These steps follow a logical
order, that means following the instructions will make your kit building
experience easier and ensures that your project will work first time when
finished.

You will notice a check box ! as each instruction gives you a simple task, or
direction, to follow. When the task is finished, make a small check mark in the
box to show that part has been completed. This will allow you to keep track of
where you left off when returning from a break.

For example, a direction may read:

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VEC-121K Owner's Manual Crystal Radio Set Kit

!

Tighten the screw until snug, this will make a good electrical connection

between the Fahnstock clip and wire.

When finished following the directions, “check off” that the step has been done.

"

Tighten the screw until snug, this will make a good electrical connection

between the Fahnstock clip and wire.

Don’t rush!

Have you ever notic ed that when you try to rush do ing something, it never turns
out right? Don’t try to build the crystal set receiver in one day! The time spent
building a kit is most of the fun. We will be “breaking down” the kit assembly
into several phases. For example, the first phase is preparing the “breadboard”.
The next kit phase involves winding the c oil.

Working with wire:
Unspooling:

Your kit includes a 100-foot roll of 18 AWG enamel-coated wire.
This wire is used to wind the tuning coil, for your receiver’s antenna, and is also
to be used for making connections between the radio components. Do not
remove the wire tie from the roll of wire until you are ready to use it. There is a
right and wrong way to remove wire from the spool! Never allow the wire to
uncoil, like a Slinky

TM

toy! Doing so will cause the wire to twist and make kinks
when you try to use it. Instead, hold the spool of wire in both hands, and
carefully unroll the wire from the spool. Re-tape the unused portion when
finished.

Removing insulation:

Electrical connections are made by removing the
insulation from the enamel wire. When you need to make an electrical
connection, you will be instructed to remove the wire insulation. We will tell
you where the insulation should be removed, and how much to remove. This can
be done by using a small piece of 150 grit sandpaper. Fold the sandpaper in half
so the “sandy” sides face together. Place the wire into the sandpaper fold, and
slide the sandpaper back-and-forth over the wire while applying a gentle
pressure. Turn the sandpaper every so often to fully remove all of the insulation.
Gently scraping the insulation with a small penknife will also work. Lay the wire
on a piece of scrap board, and draw the knife blade over the insulation to scrape
it away. Always scrape in a direction away from your body!

All of the insulation must be removed to make a good electrical connection. The
bare area of the copper wire should be bright and shiny when you are finished.

Making connections:

The directions will tell you to make one of two types of connections: “End”
connections or “through” connections.

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VEC-121K Owner's Manual Crystal Radio Set Kit

End Connections:

connected. To make an end connection, you will have to remove about 1” of
insulation from the wire and form the end into a “fishhook” shape, as shown
below.

In the following drawing, a wire end connection is used to make an electrical
connection to one of the Fahnstock clips mounted on the pine board. Note we
show the wire as a “dotted line” where it passes under the Fahnstock clip. When
the Phillips screw is tightened, a good electrical connection is made. The
drawing shows how the wire hook is placed between the Fahnstock clip and
board.

End connections are made when the end of a wire is

Through conne ctions are used when the wire goes to a electric al connecti on at a
Fahnstock clip, and then continues on to make one or more connections to other
points. T he directions will tell where to make a through connec tion on a wire,
and how much insulation needs to be removed.

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VEC-121K Owner's Manual Crystal Radio Set Kit

The wire insulation is removed where shown in the directions, and made into a
half loop as shown above.

The above d rawing shows a through c onnectio n being made to a Fahnsto ck clip.
The dotted line shows where the wire runs under the clip body.

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VEC-121K Owner's Manual Crystal Radio Set Kit

PARTS LIST

You are just about ready to begin your kit building adventure! But first, let’s
take a few minutes to make sure everything needed is present and accounted for.
If any parts a re missing or damaged , you’ll need to refer to the directio ns given
in the Vectronics kit warranty section of the manual.

Qty Part Description

"

!

8 Phillips head screws

!

1 5 inch length of white 2-1/2” diameter PVC plastic pipe

!

1 100 foot spool of 18 AWG enamel coated wire.

!

6 Fahnstock clips.

!

1 Tuning capacitor shaft extension

!

1 Tuning capacitor

!

1 Tuning knob

!

1 Double-sided foam tape

!

1 Earphone

!

1 Pine board , 3/4” high by 5-1/4” deep by 6” wide

!

1 Insulated stranded wire, 7 feet long

!

1 27K resistor (red-violet-orange-gold)

!

1 1N34A germanium diode

Fahnstock clips

Tuning capacitor.

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VEC-121K Owner's Manual Crystal Radio Set Kit

Resistor:

Germanium diode:

1N34A

STEP-BY-STEP CONSTRUCTION

8