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Vectronics VEC-1290K Manual

Am radio transmitter

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I
IMPORTANT WARRANTY INFORMATIONI 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 js
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
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, well 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: Kits-in progress and completed kits are specifically
excluded from coverage by the Vectronics warranty. However, as a service to customers,
technicians are available
evaluate and repair malfunctioning kits for a minimum service fee
to
of $18.00
hour rate) plus $7.00 shipping and handling (prices subject to change). To qualify
('/a
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 536.00, subject to change), our technicians will contact you in advance by telephone
before performing the work. Defective units should be shipped prepaid
Vectronics
300 Industrial Park Road
Starkville, MS 39759
When shipping, pack your kit well and include the minimum payment plus shipping and
handling charges (525.00 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.
to:

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Summary of Contents for Vectronics VEC-1290K

  • 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 3 CD player, tape deck or other audio source. Play vintage radio show cassettes on your favorite antique radios! The VEC-1290K is easily setup to broadcast a High-Fidelity signal in the AM broadcast band between 540 and 1710 kHz-find a clear frequency and broadcast...
  • Page 4 BEFORE YOU START BUILDING Experience shows there are four common mistakes builders commonly make. Avoid these, and your kit will probably work on the first try! 1. Installing the Wrong Part: It always pays to double-check each step. A 1K and a IOK resistor may look almost the same, but may act very differently in an electronic circuit! The same is true for capacitors-a device marked 102 (or .001 uF) may have very different operating characteristics from one marked...
  • Page 5 VEC-1290K Instruction Manual AM Radio Transmitter fill in behind the lead as you extract it-especially if you are working on a double-sided board with plate-through holes. Should this happen, try heating the pad again and inserting a common pin into the hole. Solder won't stick to the pin's chromium plating.
  • Page 6 VEC-1290K Instruction Manual AM Radio Transmitter Kit and fatter at the ends than resistors. When doing your inventory, separate out any chokes and consult the parts list for specific color-code information. Reading Capacitors: Unlike resistors, capacitors no longer use a color code for value identification.
  • Page 7: Parts List

    VEC-1290K Instruction Manual AMRadio Transmitter PARTS LIST Your kit should contain all of the parts listed below. Please identify and inventory each item on the checklist before you start building. If any parts are missing or damaged, refer to the manual's warranty section for replacement instructions.
  • Page 8: Parts Placement Diagram

    VEC-1290K Instruction Manual AM Radio Transmitter Switches/Jacks/Misc.: Designation Qty Part Description DPDT push-action switch RCA phono jack, PC-mounted 2.1 mm DC coaxial power jack 2-pin PC board mount headers JMP1,2,3,4,5 2-pin jumpers, shorting 16-pin IC socket 8-pin IC socket 4" nylon cable tie...
  • Page 9 VEC-1290K Instruction Manual AM Radio Transmitter Kit STEP-BY-STEP ASSEMBLY INSTRUCTIONS Before assembling your kit, please take time to read and understand the VEC kit warranty printed on the inside cover of this manual. Read through the assembly instructions to make sure the kit does not exceed your skill level.
  • Page 10 VEC-1290K Instruction Manual AM Radio Transmitter leads should be formed as shown below. Install and solder resistors at the following locations: Important Note: the fourth resistor color band is for tolerance, and is not called out in the following steps.
  • Page 11 VEC-1290K Instruction Important Note: When installing the two-pin jumper headers, the shorter pins are inserted into the pc board., 10. Locate the two 100-pF ceramic trimmer capacitors. When inserting, ensure that the three component leads are fully seated and that the capacitor body is level.
  • Page 12 VEC-I290K Instruction Manual AM Radio Transmitter Phase 4: Molded choke installation Important Note: only the first three color bands are specified in the following directions. The fourth band is for tolerance and may be disregarded. 1. Locate the 1000-uH molded choke (brown-black-red). Install and solder at location L1.
  • Page 14 VEC-1290K Instruction Manual AM Radio Transmitter 2. Locate the 2N3904 plastic transistor. Form its leads so it sits close to the board at location Q1. Note that the device has a rounded and flat side. Align the package to conform to the silk-screened legend.
  • Page 15: Testing And Alignment

    Initial alignment sets the transmitter to the desired operating segment of the AM broadcast band. The VEC-1290K oscillator stage covers the AM band in three preset ranges. These are determined by the presence or absence of a jumper at locations JMP1 and JMP2.
  • Page 17 1'EC-1290K Instruction Manual AM Radio Transmitter clip on JMP 1. Capacitor C 12 will now tune the transmitter frequency from 870 to 1420 kHz. A frequency counter is the quickest method to set the transmitter precisely on channel. Attach the counter input to either side of resistor R3. The signal is strong enough at this point to drive any 50-ohm or high-impedance counter without problem.
  • Page 18 Audio Gain Setting: The VEC-1290K will accommodate a wide range of audio levels, from "line level" cassette or CD deck feeds, or even the very low output from a local mike. Removing capacitor C2 will reduce the amplifier gain; this is the preferred configuration for usually high line-level audio sources such as when taking an audio feed directly from a speaker output.
  • Page 19 2. Rated for at least 300 mA continuous 3. Be equipped with a 2.1 mm coaxial power jack, center pin The VEC-1290K can be operated at lower supply voltages down to about 9 volts, but the transmitter range will be reduced. The transmitter is powered when the SW1 push shaft is in the depressed position.
  • Page 20 The new expanded AM broadcast band between 1610 and 1710 kHz is still relatively free of new station assignments. Likewise, many VEC-1290K's will make it down to as low as 530 kHz, a relatively quiet frequency in most areas.
  • Page 21 Only high-quality components and proven circuit designs are used i Vectronics kits. In very rare instances is a defective component the source of problem. Replacement of defective parts is covered in the Warranty section Ninety-five percent of the kits returned for factory repair are due to solderin problems or parts in the wrong locations.
  • Page 22 DC coupled, with no interstage coupling capacitors or modulation transformers to limit or tailor the audio response. Antenna and matching: The VEC-1290K is supplied with an attached 6-foot wire radiator. This antenna meets current FCC Part 15 requirements for unlicensed RF transmitters. The antenna is extremely capacitive reactive at broadcast band frequencies, and presents a very high impedance to the transmitter.
  • Page 23 antenna to the low-impedance of the final RF stage transistor. Jumpers are used to select the optimum amount of inductance for segments of the AM band. Trimmer capacitor C11 allows for a precise match at the operating frequency-or, maximum transfer of RF energy to the antenna. The pi- network is in essence is a low-pass filter configuration, and also offers some degree of harmonic energy rejection.
  • Page 25 VEC-1290K Instruction Manual AM Radio Transmitter Vectronics has designed a matching enclosure just for your VEC-1290K AM Radio Transmitter Kit. The matching enclosure is an all metal box which includes knobs, hardware, decals, and rubber feet. Model: VEC-1290KC. To install your receiver in the VEC-1290KC matching enclosure follow these instructions (read all instructions before beginning ...