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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
Return Policy on kits VVhen Purchased Directly From Vectronics: Your VEC kit may be
in its pre-assembled condition only.
returned to the factory
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
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.
before you
However,
contact Vectronics,
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: 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 track.
Factory Repair After You Begin Assembly:
excluded from coverage by the Vectronics warranty.
technicians are available to evaluate and repair malfunctioning kits for a minimum service fee
of $18.00 (1/2 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:
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.
before you
begin construction.
The reason for this stipulation is,
before you
begin construction, and
please look carefully
to confirm you haven't misread
Kits-in progress and completed kits are specifically
However, as a service to customers,

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Summary of Contents for MFJ VEC-820K

  • Page 1 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 before you allows returns, your kit must be returned begin construction.
  • Page 3: Tools And Supplies

    CW Filter INTRODUCTION Thank you for purchasing the VEC-820K CW Filter kit. The VEC-820K consists of a four stage, switch selectable band pass CW filter, using selected components that will make "cleaning up" CW signals effortless and easy. With the VEC- 820K you bring up any hard to hear signal out of a "band pile up,"...
  • Page 4 V EC-820K Instruction Manual CW Filter BEFORE YOU START BUILDING Experience shows there are jour common mistakes builders make. Avoid these. and your kit will probably work on the first try! Here's what they are: 1. Installing the Wrong Part: It always pays to double-check each step. A 1K and a 10K resistor may look almost the same, but they may act very differently in an electronic circuit! Same for capacitors--a device marked 102 (or.001 uF) may have very different operating characteristics from one marked 103 (or...
  • Page 6 V E C - 2 0 K In s tr u c ti o n M a n u a l C W F il te r K i t orientation. Many specialized diodes and low-current voltage regulators also use this type packaging.
  • Page 7 VEC-820K Instruction I Manual ilter Kit PARTS Your kit should contain all of the parts listed below. Please go through the parts bag to identif and inventory each item on the checklist before you start building, If any parts are missing or damaged, refer to the warranty section of this manual for replacement instructions.
  • Page 9 ['EC-820K Instruction .manual Clf' Filter STEP-BY-STEP ASSEMBLY Before assembling your kit, please take time to read and understand the VEC kit warranty printed on the inside cover of this manual. Also, read through the assembly instructions to make sure the kit does not exceed your skill level. Once Finally, if you haven't you begin construction, your kit will be non-returnable.
  • Page 10 1'EC-820K Instruction afanual CIf Filter 7. Locate capacitor C6 (1000pF). This is yet another polystyrene capacitor and will be marked "1000J" (actual value in pF). Carefully install C6 in the same manner as C5, and solder in place. 8. Locate capacitor C7 (1000pF). This is yet another polystyrene capacitor and will be marked "1000J"...
  • Page 11 17 ('-820K Instruclion .Manual Cff' Filter 17. Loca,td r"c'sistor R4. This is a 1.82M resistor (brown-gray-red-Nellmc brotk W). "~'arefiilly bend the leads close the resistor body as in Step #11. 20. Insert R> into its mounting holes so the resistor body rests against the board.
  • Page 12 F EC-820K Instruction Afanua/ CII'Fi/ter 30. Insert RIO into its mounting holes so the resistor body rests against the board. Solder in place and trim the leads. 31. Locate resistor R11. This is 24.3K resistor (red-yellow-orange-red- brown). Carefully bend the leads close to the resistor body as in Step #I1. 32.
  • Page 13 ITC-820k Instrrtction.Manual CII' Filter 45. Locate capacitor CIO (IOuF). This is an electrolytic type capacitor and will be marked "lOuF" (actual value in uF). Carefully install C9: be sure to orient the negative end of the capacitor properly. Please refer to the section titled, "Parts Placement", Figure I for correct orientation of CIO.
  • Page 14 F EC-820K Instruction .t fanual Cff Filter Kit 57. Connect the other end of the insulated wire located at the INPUT location on the circuit board to Point A on SW 1. Solder in place and trim the excess lead from the switch contact. 58.
  • Page 15 sockets for U 1 and U2. Please refer to the "Parts Placement" section. Figure 1 for proper orientation. Be sure not to bend any of the pins underneath the IC body, and that all pins are inserted into the socket. At this point, your kit is finished and it's time to take a well-earned break! When you come back.
  • Page 16 Now that assembly and inspection is completed, you're ready to begin the testing and alignment phase of construction. The best way to test the VEC-820K is with a calibrated audio signal generator and oscilloscope. However. VEC-820K does not require any alignment. If all components are installed correctly and in the proper places, the center frequency of the filter will be between 750-800 hertz.
  • Page 17 You may use the VEC-820K with any communications receiver or scanner with a BFO (Beat Frequency Oscillator). You can also use the VEC-820K with a ham-radio transceiver in either LSB or CW mode. The VEC-820K requires a 9- volt battery power source.
  • Page 18: In Case Of Difficulty

    I E('-830/: Instruction _Manual Cll' Filter communications receiver or scanner with a BFO control. use this control to fine tune the received CW signal. If the receiver or scanner you are using does not have a BFO control, it will be very difficult trying to tune the signal in properly.
  • Page 19 THEORY OF OPERATION AND SPECIFICATIONS Circuit Description: The VEC-820K uses two UA747 operational amplifier integrated circuits to form four low Q cascaded stages NNith no insertion loss. This results in a ven narrow band« idth and extremely high skirt rejection with minimum audible ringing.