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Vectronics VEC-104K Instruction Manual

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VERY IMPORTANT! PLEASE READ:
Your Receiver Kit carries Vectronics' respected No Matter What guarantee specifically to the extent that
you may return the entire kit UNASSEMBLED for credit or refund. If you have never built an
electronics kit before, PLEASE study the book carefully before unpacking the small parts. Once you
begin soldering parts, neither Vectronics or any dealer can accept the return of this kit for any reason
whatsoever.
NOTE: We have designed this book and the receiver itself to assure that you can build it successfully
and enjoy using it as soon as construction is completed. If, after building your receiver, double-checking
all assembly steps and going over the preceding trouble-shooting suggestions, you are still having a
problem, please contact Vectronics at 1-601-323-5800. Before calling, please be prepared to explain
your exact difficulty as clearly as possible, and please be sure you have installed the right parts in the
right places! If needed, your receiver can be repaired by Vectronics provided that it has been completely
assembled, using rosin-core solder only. Call for quote.
Vectronics, INC.
1007 Hwy 25 South
Starkville, MS 39759 USA
Vectronics will verify repairs on any unit requiring more than the minimum service fee covers with the
owner of the unit by phone.
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Summary of Contents for Vectronics VEC-104K

  • Page 1 UNASSEMBLED for credit or refund. If you have never built an electronics kit before, PLEASE study the book carefully before unpacking the small parts. Once you begin soldering parts, neither Vectronics or any dealer can accept the return of this kit for any reason whatsoever.
  • Page 2 Once you begin soldering parts, you assume responsibility as the radio's manufacturer. Neither Vectronics nor its dealers can be held accountable for the quality or outcome of your work. Because of this, Vectronics and its dealers cannot accept the return of any kit-in-progress or completed kit for any reason whatsoever.
  • Page 3 IC to drive the radio's speaker. The Motorola FM-receiver IC will do the rest! The fun isn't over when your kit is done. You'll quickly discover the VEC-104K is a "serious" receiver with superb SENSITIVITY (ability to pull in weak stations.) Tuning in stations is easy. This is because we use an expensive ball-bearing reduction-drive tuning capacitor rather than a cheap potentiometer for channel selection.
  • Page 4 A. Your radio's antenna picks up all kinds of VHF stations -- including fire, police, FM broadcast, and aircraft. The VEC-104K uses a BANDPASS FILTER to get rid of unwanted signals. B. Desired two-meter signals pass through the filter without being affected. They are boosted by a LOW-NOISE AMPLIFIER (LNA).

  • Page 5: Receiver Controls

    The receiver may be powered by an internal 9-volt battery or an external power source. Vcc to U1 is regulated at 5.0 volts by U3, while Q1 and U2 operate at the input source voltage. The VEC-104K operates on any well-filtered DC source between 6.5 to 15 volts.
  • Page 6 MODEM device). Signal level at this jack is not affected by the volume control setting. ANTENNAS FOR YOUR VEC-104K: The VEC-104K is especially designed to work with the 19" rod antenna provided. However, to explore for distant signals, you may wish to try an outdoor antenna such as the one shown below:...
  • Page 7 When it comes to selecting the right antenna, you can overdo a good thing. A high-gain 2-meter array or "powered" antenna could easily overload the VEC-104K's sensitive LNA and degrade rather than improve performance -- especially if you live in a high-signal urban area.
  • Page 8 CW/SSB SEGMENT: This portion of the band is reserved for modes other than FM. Most signals won't be readable on your VEC-104K. TIPS FOR TUNING IN FM SIGNALS: When scanning for signals, try tuning with the Squelch control open so you can hear the receiver's background noise (turn the volume down to a comfortable level).

  • Page 9: Signal Strength

    SIGNAL STRENGTH: You can estimate the relative strength of an incoming signal by the way it tunes. The diagram below illustrates how this works: SIGNAL CLASSIFICATION WEAK SIGNAL: Little noise reduction either side of center, audible background noise under the voice. MODERATE AND STRONG SIGNALS: Deep noise reduction either side of center, audible background noise under the voice (such signals are often called "full quieting ").
  • Page 10 GLOSSARY OF 2-METER FM TERMS: AUTOPATCH: Connects a repeater to the phone system so users can place phone calls over the radio. BAND PLAN: Rules and agreements that determine how an amateur band is shared among useres. BASE STATION: Two-way radio permanently installled in a building. CONTROLLER: Automated switching unit that controls repeater operation.
  • Page 11 ELECTRONIC TERMINOLOGY: AF (AUDIO FREQUENCY): Occuring in the audio spectrum. ALIGNMENT: One-time adjustment -- usually during initital testing. AMPLIFIER: Device increasing the strength of electronic signals. BANDPASS FILTER: Circuit passing signals in a specified frrequency range,but rejecting signals above and below that range. COLD SOLDER JOINT: A defective solder connection caused by incomplete heating or metal corrosion.

  • Page 12: Before You Start Building

    BEFORE YOU START BUILDING: Experience shows there are FOUR COMMON MISTAKES builders make. Avoid these, and your kit will probably work on the first try! 1. INSTALLING THE WRONG PART: It pays to double check. A 1K and 10K resistor look almost the same, but will act very diferently in an electronic circuit! 2.
  • Page 13 STEP-BY-STEP CONSTRUCTION: You'll assemble the VEC-104K in stages -- starting with the A.F. Amplifier. Please follow the published order for installing parts. Each instruction has two check boxes. Check the first box as you assemble the unit. You'll use the second box later on -- when you check your work.
  • Page 14 [] [] Install each of the four 1/4" PC-board mounting spacers (one at each corner) using #4-40 nuts. [] [] Locate parts and install the mounting stud for the radio's collapsible antenna as shown below: This completes PC-board assembly of the VEC-104K. INSPECTION:...
  • Page 15 INITIAL TESTING OF THE VEC-104K: [] Thoroughly clean your work area of all wire-clippings, solder scraps, and debris before testing. Place PC board on a clean non-conductive non-skid surface (poster board, etc.). [] Press the POWER SWITCH to its OFF position (shaft out). Turn VOLUME and SQUELCH controls (R12, R13) counter clockwise (CCW).
  • Page 16 [] Slowly adjust L4 until the generator signal fully quiets the VEC-104K METHOD #2 -- SCANNER OR EXTENDED-COVERAGE 2-METER HT: The VEC-104K's VFO should oscillate at 135.3 MHz when tuned to 146.0 MHz. Use a scanner to tell when VFO is properly tuned.

  • Page 17: Final Steps

    [] Stretch or compress the turns of each coil (L1, L2) for maximum quieting (repeat a couple of times until the best adjustment for both coils is found). This concludes final tune up of your VEC-104K 2-meter receiver. FINAL STEPS: [] Install the lid and secure in place with the two screws provided.

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