Vectronics VEC-821K - Manual (Page 4)

VEC-821 K Instruction Manual Super CW 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: It always pays to double -check each step. A 1 K and a
10K resistor may look almost t h e s a m e , b u t t h e y m a y a c t v e r y 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: Always check the polarity of electrolytic
capacitors to make sure the positive (+) lead goes in the (+) hole on the
circuit board. T r a n s i s t o r s h a v e a f l a t s i d e o r e m i t t e r t a b t o h e l p y o u
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: Inspect fo r cold-solder joints and solder 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
Soldering Tips below).
4. Omitting or Misreading a Part: T h i s i s e a s i e r t o d o t h a n y o u m i g h t think!
Always double-check to make sure you completed each step in an assembly
sequence.
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-thousand-one") before feeding solder
to the connection. Surfaces must become hot enough for solder to
flow smoothly.
F e e d s o lder 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.