Vectronics VEC-841K User Manual

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 i nsta lli ng a nd sol deri ng pa rt s, you essenti al ly tak e over the rol e of the devic e's
manufacturer . From this point on, neither Vect ronics nor its dea lers can reas onably be held
accountab le for the qua lity 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 b uilder, we urge you to read the manual
carefully a nd determine whether or not you're r eady to tak e on the job. If you wish to c hange
your mind and return your ki t, you may--b ut you must do i t before you begin c ons tr uc ti on, a nd
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 Vect ronic s, please look carefully to c onf ir m you haven't misr ea d
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 a re r a re. However, if you disc over a n it em duri ng your pr e- c onst r uct i on
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 defec tive and appear s 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 trac k.

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, tec hnicia ns ar e availa ble t o evaluate a nd repai r malf unctioni ng 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 fi x (or $36.00, subject to change), our technicians will contact you in
advance by telephone b efore p erforming t he work. Def ective unit s should b e shipp ed prep aid
to:

Vectronics
1007 HWY 25 South
Starkville, MS 39759

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 a nd a day time phone number where you may be reac hed.

VEC-841K Owner's Manual Tunable SSB/CW Audio Filter Kit

INTRODUCTION

Thank you for purchasing the VEC-841K Tunable CW Audio Filter kit. The
VEC-841K consists of a four stage, switch selectable band pass CW filter, using
selected components that will make “cleaning up” CW signals effortless and
easy. Featuring razor sharp selectivity and extremely steep sided skirts, and a
Tunable Notch, makes even the weakest signal stand out. Also, the VEC-841K
has a built-in 1 watt audio amplifier that will easily drive headphones or an
external speaker. With the VEC-841K you bring up any hard to hear signal out
of a “band pi le up” for ea sy listening, or get ri d of unwanted, annoying signals.
The VEC-841K also features a headphone output that will allow the use of
standard mono headphones. The VEC-841K is powered from any 9-18 volt DC
power supply.

TOOLS AND SUPPLIES

Construction Area:

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, while providing protection for the underlying table or desk. Well­diffused overhead lighting is a plus, and a supplemental high-intensity desk lamp
will prove especially helpful for close-up work. Safety is an important
consideration. Be sure to use a suitable high-temperature stand for your
soldering iron, and keep the work area free of combustible clutter.

Universal Kit-building Tools:

additional items to complete, virtually all construction projects require a work
area outfitted with the following tools and supplies:

!

30-60 watt Soldering Iron

!

High-temperature Iron Holder with a Moist Cleaning Sponge

!

Rosin-core Solder (thin wire-size preferred)

!

Needle Nose Pliers or Surgical Hemostats

!

Diagonal Cutters or "Nippy Cutters"

!

Wire Strippers

!

Solder Sucker, Vacuum Pump, or Desoldering Braid

!

Bright Desk Lamp

!

Magnifying Glass

Kit construction requires a clean, smooth, and well-lighted

Although your particular kit may require

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VEC-841K Owner's Manual Tunable SSB/CW Audio Filter Kit

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! Here's what they are:

1. Installing the Wrong Part:

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 .01uF).

2. Installing Parts Backwards:

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 mounting position. ICs have a notch or dot at one end indicating
the correct direction of insertion. Diodes have a banded end indicating
correct polarity. Always double-check--especially before applying power to
the circuit!

3. Faulty Solder Connections:

bridges. Cold solder joints happen 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:

Always double-check to make sure you completed each step in an assembly
sequence.

Soldering Tips:

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
allow maximum heat transfer. Allow the tip of your iron to contact both the lead
and pad for about one second (count "one-thousand-one") 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, wetting all exposed surfaces. Apply
solder sparingly, and do not touch solder directly to the hot iron tip to promote
rapid melting.

Cleanliness and good heat distribution are the two secrets of

It always pays to double-check each step. A 1K

Always check the polarity of electrolytic

Inspect for cold-solder joints and solder

This is easier to do than you might think!

Desoldering Tips:

these instructions carefully! First, grasp the component with a pair of 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
fill in behind the lead as you extract it--especially if you are working on a

2

If you make a mistake and need to remove a part, follow

VEC-841K Owner's Manual Tunable SSB/CW Audio Filter Kit

double-sided b o ar d with plat e-thr o ugh hol es. Sho uld this ha pp e n, tr y heat ing 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 multi-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:

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 project are more informative and more fun when you
take your time. Enjoy!

Sorting and Reading Resistors:

a color code (shown below). You don't have to memorize this code to work with
resistors, but you do need to understand how it works:

Kit construction requires the ability to follow detailed

The electrical value of resistors is indicated by

Resistor Color Code

Black = 0 (tens)
1st Digit
2nd Digit
Multiplier

Tolerence

(gold or silver)

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 sort and 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.

Brown = 1 (hundreds)

Red = 2 (K)

Orange = 3 (10K)

Yellow = 4 (100K)

Green = 5 (1Meg)

Blue = 6
Violet = 7
Gray = 8
White = 9
Silver = 10%
Gold = 5%

Some VEC kits may contain 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 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.

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VEC-841K Owner's Manual Tunable SSB/CW Audio Filter Kit

l

Reading Capacitors:

value identification. Instead, the value, or a 3-number code, is printed on the
body.

Value Code

10 pF = 100
100 pF = 101
1000 pF = 102

.001 uF = 102*

.01 uF = 103
.1 uF = 104

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 from pF to uF occurs at 1000 pF (or .001 uF)*. Today, most
monolithic and disc-ceramic capacitors are marked with a three-number code.
The first two digits indicate a numerical value, while the last digit indicates a
multiplier (same as resistors).

Electrolytic capacitors are always marked in uF. Electrolytics are polarized
devices and must be oriented correctly during installation. If you become
confused by markings on the case, remember the uncut negative lead is slightly
shorter than the positive lead.

Diodes:

Always look for the banded or cathode end when installing, and follow
instructions carefully.

Diodes are also polarized devices that must be installed correctly.

Unlike resistors, capacitors no longer use a color code for

E

ectrolytic

1 uF

1uF

|

35V

|

-

+

Multilayer

(270 pF)

271

Ceramic Discs

(.001 uF) (.1 uF)

102

104

Cathode

(shorter Lead)

Diode

Transistors:

power is applied. Transistors in metal cases have a small tab near the emitter
lead to identify correct positioning. Semiconductors housed in small plastic
cases (TO-92) have an easily-identified flat side to identify mounting orientation.
Many specialized diodes and low-current voltage regulators also use this type
packaging. Larger plastic transistors and voltage regulators use a case backed
with a prominent metal tab to dissipate heat (T-220). Here orientation is
indicated by the positioning of the cooling tab.

4

If transistors are installed incorrectly, damage may result when

LED

VEC-841K Owner's Manual Tunable SSB/CW Audio Filter Kit

Metal Can Device Plastic Device Tab-cooled Device

Emitter

Flat Side

Integrated Circuits:

marking located on one end of the device. A corresponding mark will be silk­screened on the PC board and printed on the kit's parts-placement diagram. To
identify specific IC pin numbers for testing purposes, see the diagram below.
Pin numbers always start at the keyed end of the case and progress counter­clockwise around the device, as shown:

Installation

Key

Proper IC positioning is indicated by a dot or square

8 7 6 5

Installation

Key

1 2 3 4

Pin Numbers

Metal Tab

PARTS LIST

Your kit should contain all of the parts in the foll owing list. Please go thro ugh
the parts bag to identify and inventory each item on the checklist before you start
building. If any par ts are missing or damaged, r efer to the warranty section of
this manual for replacement instructions. If you can't positively identify an
unfamiliar item in the bag 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 inventory as an
opportunity to sort and arrange parts so you can identify and find them quickly.

Qty Part Description Designation

"

Fixed Resistors:

!

1 2.7 ohm resistor (red-violet-gold) R35

!

1 5.1 ohm, 1/2 watt resistor (green-brown-gold) R32

!

1 68 ohm resistor; 1/2 watt (blue-gray-black) R36

!

3 470 ohm resistor (yellow-violet-brown) R10, R28, R29

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VEC-841K Owner's Manual Tunable SSB/CW Audio Filter Kit

!

1 2.2K ohm resistor (red-red-red) R11

!

6 4.7K ohm resistor (yellow-violet-red) R5, R6, R7, R8

R18, R33

!

10 10K ohm resistor (brown-black-orange) R1, R9, R12, R13
R19, R20, R23
R30, R31, R34

!

2 24K ohm resistor (red-yellow-orange) R3, R22

!

5 100K ohm resistor (brown-black-yellow) R2, R14, R15

R17, R21

!

1 130K ohm resistor (brown-orange-yellow) R4

!

1 240K ohm resistor (red-yellow-yellow) R16

Capacitors:

!

4 .1uF disc ceramic capacitor (104, 104Z) C1, C3, C16, C17

!

3 .01uF disc ceramic capacitor (103, 103Z) C2, C4, C15

!

4 1000pF polystyrene capacitors (1000J) C5, C6, C7, C8

!

1 100uF electrolytic capacitor C12

!

2 470uF electrolytic capacitor C11, C14

!

1 10uF electrolytic capacitor (radial leads) C13

!

2 10uF electrolytic capacitor (axial leads) C9, C10

Semi-conductors:

!

2 TL084 quad operational amplifiers IC U2, U3

!

1 LM380 2 watt audio amplifier IC U1

Miscellaneous:

!

1 10K ohm horizontal trimpot (10K or 103) R25

!

1 500K ohm horizontal trimpot (500K or 504) R24

!

2 500K Dual Linear potentiometer R26, R27

!

2 2-pole 2-position push button switch SW1, SW2

!

1 RCA phono jack J4

!

1 1/4" stereo phone jack J1

!

1 3.5mm stereo jack J2

!

1 2.1mm coaxial DC jack J3

!

3 14-pin IC sockets For U1, U2, U3

!

2 6" insulated stranded wires Circuit wiring

!

1 VEC-841K PC board

!

1 Instruction Manual

PARTS PLACEMENT DIAGRAM

6