VEC-1320K/1330K/1340K/1380K Owner's
Manual
15
This concludes the first phase of construction (small generic parts). Next, you'll
install frequency-determining components. However, before you start, this
might be a good time to take a well-deserved break! Be sure to check transistor
and diode positioning and polarity before moving on.
Stage 2: Frequency-Determining Parts
In this section, you'll select a
specific set of instructions for your particular kit.
However, before you do this, please review these two important general
construction tips that apply to all four versions.
Installing Multilayer Capacitors:
There are 9 multilayer capacitors in your
kit. A multilayer cap is similar to a surface-mount "chip" capacitor, except that
it has a lead spot-welded onto each end of the capacitor body. Each cap is then
coated with an epoxy coating. Multilayers have superior radio-frequency
operating characteristics, but the lead welds may fail if the leads are placed
under stress while being heated during installation or removal. For this reason,
never use force to seat a multilayer cap
into the PC board. If the spacing isn't
right, pre-form the leads to the correct spacing before installation!
Incorrect
Ooops!
Correct
Winding T1 and L4:
The receiver's pre-selector circuit and the transmitter's
low-pass filter each use a high-Q toroid inductor wound on a T50-2 form (T50
means the form is .50" in diameter and 2 designates the "mix" of powdered iron
used to make it). When winding toroid coils, remember
the number of turns are
counted inside the form
. This means, if the instructions call for a 12-turn coil,
you must pass the wire through the center of the core 12 times. When winding
these coils, be sure to pull each turn up tight before starting the next. If the coil
is wound loosely, inductance increases. At L4, this could reduce transmitter
output power.
