Vectronics VEC-1290K User Manual

IMPORTANT WARRANTY INFORMATIO NI PLE ASE REA D

p

I

Return Policy on Kits When Not Purchased Directly From V ectronics: 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,

Vectronics Warrants: Your kit contains each item specified in the parts list.

Missing Parts: If you determine, during your pre-construction inventory, th at 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 c onfirm you ha ven't misr ead
the marking on one of the other items provided with t he kit . A lso, make cert ain an altern ative
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 comp onent is more suitable,

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 brok en or unserviceable, we'll replace it. Just ret urn 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 ca n replace them for a
reasonable charge. Simply contact the factory with a com plete 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
of $18.00
for repair service, your kit must be fully completed , u nm odified, 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 u nit s should be shipped prepaid

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,

rovide a valid UPS return address and a day time phone number where you may be reached.

hour rate) plus $7.00 shipping and handling (prices subject to change). To qualify

('/a

Vectronics

300 Industrial Park Road
Starkville, MS 39759

to

evaluate and repair malfunctioning kits for a minimum service fee

to:

VEC-1290K Instruction Manual AM Radio Transmitter

INTRODUCTION

Own and operate your own low-cost AM broadcast station! You're the disc
jockey or talk show host-play music from your 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
interference free to your neighbors! The transmitter is
either 9-kHz European or 10-kHz American channel spacings! Accepts audio
from standard line -leve l or micro p ho ne-le vel sour ce s. True hi gh-le ve l Cla ss C
modulation delivers good modulation depth and linearity. No FCC license is
required, its perfectly legal under Part 15 of the FCC rules. This Vectronics kit
features a professional quality epoxy PC board, with solder mask and silk­screened parts legend to make assembly a breeze!

Construction Area: Kit construction requires a clean, smooth, and welllighted
area where you can easily organize and handle small parts without losing them.
An inexpensive sheet of white poster board makes an excellent construction
surface and provides protection for the underlying table or desk. Well-diffused
overhead lighting is a plus, and a supplemental high-intensity desk lamp is
especially helpful for close-up work. Safety is always important! Be sure to use
a suitable high-temperature stand for your soldering iron, and keep the work
area free of combustible clutter.

compatible with

fully

Universal Kit-buil di ng T o o ls: Altho ugh your pa rt icul ar kit ma y req uir e
additional items for completion, virtually all construction projects require a
work area outfitted with the following tools and supplies:

BEFORE YOU START BUILDING

y

Experience shows there are four common mistakes builders commonl y make.
Avoid these, and

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
103 (or .01 uF).

2. Installing Parts Backwards: Always check the polarity of electrolytic
capacitors to make sure the positive (+) lead goes in the (+) hole on the
circuit board. Transistors have a flat side or emitter tab to help you identify
the correct mounti ng po sition. IC s have a no tch or dot at one end indi cating
the correct direction of insertion. Diodes have a banded end indicating correct
polarity.

3. Faulty Solder Connec tions: Inspect for cold-solder jo ints and solder
bridges. Cold solder joints occur when you don't fully heat the connection
or when metallic corrosion and oxide contaminate a component lead or
pad. Solder bridges form when a trail of excess solder shorts pads or
tracks together (see Solder Tips below).

4. Omitting or Misreading a Part: This is easier to do than you might think!
Always double-check to make sure you completed each step in an assembly
sequence.

our kit will probably work on the first try!

Soldering Tips: Cleanliness and good heat distribution are the two secrets of
professional soldering. Before you install and solder each part, inspect leads
or pins for oxidation. If the metal surface is dull, sand with fine emery paper
until shiny. Also, clean the oxidation and excess solder from the soldering
iron tip to ensure maximum heat transfer. Allow the tip of your iron to
contact both the lead and pad for about one second (count "one-thousand­one") before feeding solder to the connection. Surfaces must become hot
enough for solder to flow smoothly. Feed solder to the opposite side of the
lead from your iron tip. Solder will wick around the lead toward the tip,

Desoldering Tip s: If you make a mistake and need to remove a part, fol low
these instructions carefully! First, grasp the component with hemostats or
needle-nose pliers. Heat the pad beneath the lead you intend to extract, and,
pull gently. The lead should come out. Repeat for the other lead. Solder may

VEC-1290K Instruction Manual AM Radio Transmitter

y

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. When the pad cools, remove the pin and insert the
correct component. For ICs or multiple-pin parts, use desoldering braid to
remove excess solder before attempting to extract the part. Alternatively, a
low-cost vacuum-bulb or spring-loaded solder sucker may be used. Parts
damaged or severely overheated during extraction should be replaced rather
than reinstalled.

Work Habits: Kit construction requires the ability to follow detailed
instructions and, in many cases, to perform new and unfamiliar tasks. To avoid
making needless mistakes, work for short periods when you're fresh and alert.
Recreational construction projects are more informative and more fun when
you take your time. Enj o y!

Sorting and Reading Resistors: The electrical value of resistors is indicated by
a color code (shown below). You do n't ha ve t o me mori ze thi s co d e to work
with resistors, but

ou do need to und er sta nd ho w it works:

When you look at a resistor, check its multiplier code first. Any resistor with a
black multiplier band falls between 10 and 99 ohms in value. Brown designates
a value between 100 and 999 ohms. Red indicates a value from 1000 to 9999
ohms, which is also expressed as 1.0K to 9.9K. An orange multiplier band
designates 10K to 99K, etc. To inventory resistors, first separate them into
groups by multiplier band (make a pile of 10s, 100s, Ks, 10Ks etc.). Next, sort
each group by specific value (1K, 2.2K, 4.7K, etc). This procedure makes the
inventory easier, and also makes locating specific parts more convenient later
on during construction. Some builders find it especially helpful to arrange
resistors in ascending order along a strip of double-sided tape.

This VEC kit contains molded chokes which appear, at first glance, similar to
resistors in both shape and band marking. However, a closer look will enable
you to differentiate between the two-chokes are generally larger in diameter

VEC-1290K Instruction Manual AM Radio Transmitter Kit

y

p

(

)

and fatter at the ends than resistors. When doing your inventory, separate out

chokes and consult the parts list for specific colo r-co de in formati on.

an

Reading Capacitors: Unlike resistors, capacitors no longer use a color code
for value identification. Instead, the value, or a 3-number code, is printed on
the body.

Value Code
10 pF = 100 Multilayer

F = 101

100
.001 uF = 102*

.01 uF = 103
.1 uF = 104

=

270 pF

As with resistors, it's helpful to sort capacitors by type, and then to arrange
them in ascending order of value. Small-value capacitors are characterized in
pF (or pico-Farads), while larger values are labeled in uF (or micro-Farads).
The transition fro m pF to uF occur s at 1000 pF (or .001 uF)*. Tod ay, while
most monolithic multilayer and disc-ceramic capacitors are marked with a
three-number code, you may still find a .1 uF capacitor marked either "104"
or ".1". For three digit codes, the first two digits indicate a numerical value,
while the last digit indicates a multiplier (same as resistors). The value is in
pF; thus a capacitor marke d "104" i s 100,000 pF, or. 1 uF.

Electrolytic capacitors are always marked in uF. Electrolytics are polarized
devices and must be orie nted corr ectly dur ing inst allatio n. If you beco me
confused by markings on t he ca se, remembe r the unc ut negat ive lead i s
slightly shorter than the positive lead.

Integrated Circuits: Proper IC positioning is indicated by a dot or square
marking located on one end of the devic e. A corre spond ing mark is silk­screened on the PC board and printed on the kit's parts-placement diagram. To
identify specifi c IC pin number s for t esting p urpose s, see the dia gra m below.
Pin numbers always star t at the ke yed end of the case and pro gre ss
counterclockwise aro und the de vice, as shown:

-

(y

)

p

p

gray

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. If you can't positively identify an unfamiliar item on the basis of
the information given, set it aside until all other items are checked off. You
may then be able to identify it by process of elimination. Finally, your kit will
go together more smoothly if parts are organized by type and arranged by
value ahead of time. Use this inventor y as an opportunity to sort and arrange
parts so you can identify and find them quickly.

Q Qty Part Description Designation

1 15 ohm (brown-gree n-bl ack) R2

1 1K ohm (bro wn-bl ac k-r ed ) R3

14.7K ohm

Ca

acitors:

Q Qty Part Description Designation

2 100 pF ceramic disc (101) C9,C10

1 510 pF polst yrene (5 10 ) C8
5 0.1 uF ceramic disc

ellow-violet-red

(104)

R4

C3,C4,C5,C6,C7

Semiconductors:
Q Qty Part Description Designation

1 4049 16-pin DIP i ntegrated c ircuit U1

1LM386 8-

[X] Qty Part Description Designation

1 22 uH molded choke (red-red-black) L2

2 100 uH molded choke (b rown-b lac k-bro wn) L7 ,L8
2 180 uH molded cho ke (bro wn-gray-b ro wn) L5,L6
2 330 uH molded cho ke (ora nge-ora nge-b rown) L4,L9
1 680 uH molded choke (blue-

in DIP integrated circuit U2

-brown) L3

VEC-1290K Instruction Manual AM

p

Switches/Jacks/Misc.:

0

Qty Part Description

DPDT push-action switch SW1

1 RCA phono jack, PC-mounted J1
1 2 .1 mm DC coaxial power jack J2
5 2-pin PC board mount headers JMP1,2,3,4,5
2 2 -pin jumpers, shorting

16-pin IC socket

1

18­1 4" nylon cable tie
1PC board

1 6 ' length of insulated 20-AWG solid wire ANTI

in IC socket

Radio Transmitter
Kit

PARTS PLACEMENT DIAGRAM

Designation