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Vectronics VEC-121K Manual

Crystal radio set kit

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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 installing and soldering parts, you essentially take over the role of the device's
manufacturer. From this point on, neither Vectronics nor its dealers can reasonably be held
accountable for the quality 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 builder, we urge you to read the manual
carefully and determine whether or not you're ready to take on the job. If you wish to change
your mind and return your kit, you may--but you must do it before you begin construction, and
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 Vectronics, please look carefully to confirm you haven't misread
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 are rare. However, if you discover an item during your pre-construction
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 defective and appears unused, we'll ship you a new one right away at no charge.
Missing or Defective Parts After You Begin Assembly:
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 track.
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, technicians are available to evaluate and repair malfunctioning 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 fix (or $36.00, subject to change), our technicians will contact you in
advance by telephone before performing the work. Defective units should be shipped prepaid
to:
Vectronics
1007 HWY 25 South
Starkville, MS 39759
Parts and materials lost or

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Summary of Contents for Vectronics VEC-121K

  • Page 1 From this point on, neither Vectronics nor its dealers can reasonably be held accountable for the quality 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.
  • Page 2 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 and a day time phone number where you may be reached.
  • Page 3: Tools And Supplies

    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.
  • Page 4 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,...
  • Page 5 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.
  • Page 6 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.
  • Page 7 VEC-121K Owner's Manual Crystal Radio Set Kit End Connections: End connections are made when the end of a wire is 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.
  • Page 8 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 drawing shows a through connection being made to a Fahnstock clip. The dotted line shows where the wire runs under the clip body.
  • Page 9: Parts List

    If any parts are missing or damaged, you’ll need to refer to the directions given in the Vectronics kit warranty section of the manual. " Part Description Phillips head screws 5 inch length of white 2-1/2”...
  • Page 10 VEC-121K Owner's Manual Crystal Radio Set Kit Resistor: Germanium diode: 1N34A STEP-BY-STEP CONSTRUCTION...
  • Page 11 VEC-121K Owner's Manual Crystal Radio Set Kit Before starting any construction, please read the Vectronics warranty. Kits that have been started cannot be returned for credit. Make sure this kit is within your skill level before starting assembly! Phase 1: Breadboard preparation ! Find the pine board.
  • Page 12 VEC-121K Owner's Manual Crystal Radio Set Kit Mounting hole Mounting hole ! Now, make sure that the two screw pilot holes on the pine board for mounting the coil form are correct. Refer to the drawings in the manual that show the placement for the Fahnstock clips and coil form.
  • Page 13 VEC-121K Owner's Manual Crystal Radio Set Kit Phase 2: Winding the tuning coil This portion of the assembly involves winding about 66 turns of 18 AWG enamel coated copper wire over a 2½” area of the PVC plastic coil form. This will take time, patience, planning and practice! Here are a few suggestions to help you along.
  • Page 14 VEC-121K Owner's Manual Crystal Radio Set Kit 16” wire tail ! Tuck the 16” wire tail back inside of the coil form, so it will be out of the way during winding. ! Hold the coil form in your left hand. The wire coming from the 100-foot coil should be between you and the form.
  • Page 15 VEC-121K Owner's Manual Crystal Radio Set Kit windings using the dispenser tip. Draw a very light bead of adhesive across the full width of the winding. Very little adhesive is needed for these tasks! Let the coil sit until the contact cement has fully cured! (You may use the glue sold for assembling plastic models for these tasks.
  • Page 16 VEC-121K Owner's Manual Crystal Radio Set Kit 16” wire tails ! Rewind any excess wire back onto the supply spool. Congratulations! You have just wound an inductor that has about 217-uH of inductance! Put the coil aside for now, you’ll be mounting it on the breadboard soon.
  • Page 17 VEC-121K Owner's Manual Crystal Radio Set Kit For the remaining steps, align the Fashnstock clips as shown in the drawing. ! Mount a second clip at the ANT position on the breadboard using a Phillips screw. ! Mount a clip using a Phillips screw at the DET1 position on the breadboard.
  • Page 18 VEC-121K Owner's Manual Crystal Radio Set Kit You need to know where the wire leads need to be sanded to make connections. Route the coil wire, as shown in the following diagram, by loosening the Phillips screws mounting the two Fahnstock clips labeled ANT and DET1 (as shown): 3.5”...
  • Page 19 VEC-121K Owner's Manual Crystal Radio Set Kit 5” 5.5” EAR2 Important Note: The “dotted” lines show wiring done in previous steps. ! Mark the left-hand coil wire at 5” from where it exits the coil. ! At the 5” point, remove 1” of insulation from the wire.
  • Page 20 VEC-121K Owner's Manual Crystal Radio Set Kit Only a few more steps remain, and the set will be finished. Refer to the drawing below for the last wiring steps. EAR1 DET2 ! Cut a 4½” length of 18 AWG enamel wire from the wire spool in the kit.
  • Page 21 VEC-121K Owner's Manual Crystal Radio Set Kit ! The wire should be routed so it crosses over the wire from the right end of the coil without the wires touching each other. ! Find the 27K ohm resistor (it has the Red-Violet-Orange-Gold colored...
  • Page 22 VEC-121K Owner's Manual Crystal Radio Set Kit ! A 3/8” length of each of the diode’s lead ends is sharply folded back on itself. This is done because the diode will be mounted in the DET1 and DET2 Fahnstock clips. The diode lead wires are a very small diameter, and may not be held tightly enough by the clip unless the leads are made a bit thicker.
  • Page 23 VEC-121K Owner's Manual Crystal Radio Set Kit Stator stud Rotor lug (narrow) This is the correct orientation for installing the capacitor. Note that the narrower rotor lug must be at the left hand side! Variable capacitors have two sets of plates. One set of plates remain stationary, and are called the “stator”...
  • Page 24 VEC-121K Owner's Manual Crystal Radio Set Kit ! Temporarily place the tuning capacitor as shown in the drawing. Be sure the narrowest stator lug is at the left hand side! ! Cut the free enamel wire lead from the GND clip to a length of five inches.
  • Page 25 VEC-121K Owner's Manual Crystal Radio Set Kit ! Temporarily place the capacitor at its mounting location. ! Route the free enamel wire coming from the DET1 Fahnstock clip so it follows the breadboard, and comes up and over the top of the capacitor until it reaches the stator stud.
  • Page 26 VEC-121K Owner's Manual Crystal Radio Set Kit ! Using the long nose pliers, gently twist the half loop to take up wire slack and tighten the wire wraps made over the stud. Important Note: If the stator stud is damaged beyond use, the stud located directly beneath it may be used as a backup.
  • Page 27: Testing And Alignment

    ! Using a small screwdriver or hex tool, install the tuning knob on the shaft extension. This completes the construction of the VEC-121K crystal set receiver. TESTING AND ALIGNMENT 1. Turn the capacitor shaft in a counter clockwise direction until the stop is reached.
  • Page 28 VEC-121K Owner's Manual Crystal Radio Set Kit 3. Connect a good ground connection to the crystal receiver. Use the 7 foot length of stranded hookup wire supplied with the kit to make the ground connection between a good earth ground and the Fahnstock clip on the receiver.
  • Page 29 VEC-121K Owner's Manual Crystal Radio Set Kit This diagram shows an aerial going between a pole (or tall tree trunk) and location where the receiver is located. A small length of lead-wire connects the antenna to the crystal set inside of the house. (Make sure the lead-in wire makes good electrical connection to the antenna wire!) Note the insulators between the antenna wire and the supporting structures.
  • Page 30: In Case Of Difficulty

    There is a local station at the high or low end of the dial that I can’t hear. The VEC-121K is designed to tune the entire broadcast band. However, there will be certain antenna lengths that will behave in unexpected manners at certain frequencies.