Vectronics VEC-121K - Manual (Page 30)

VEC-121K Owner's Manual Crystal Radio Set Kit
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IN CASE OF DIFFICULTY
This crystal set almost has to work, if it was built according to the directions. If
you can not hear any stations at all, go back over the assembly instructions and
try to find any errors that you might have made during construction. Perhaps
you missed removing the insulation from the wire at a connection. Or, a wire is
in the wrong place. Have a friend check your work. It’s very easy to look over a
mistake, and a fresh pair of eyes will often quickly find mistakes that elude your
detection. Factory repair is available for assembled kits that do not work.
Consult the warranty for information regarding factory service.
Here’s a quick check list of common problems.
The set receives several signals at once. This is normal for crystal sets. They
don’t have the ability to separate signals that very are strong or close in
frequency.
The tuning control has no effect. Check that the connections to the tuning
capacitor are tight, and that the proper connection points to the tuning capacitor
were used.
Signals are very weak, or I can only hear one station. Again, this may be
normal, if there are no strong signals in your area. Check your ground and
antenna connections. A longer antenna or better ground may improve things.
Set works intermittently. This sounds like a poor connection. Check that the
Fahnstock clips are making good connections to the antenna, ground and
earphone wires. If a clip won’t grip the wire properly, remove the wire and bend
the clip upwards slightly. This should restore the clasping action of the clip’s
jaw.
There is a local station at the high or low end of the dial that I can’t hear.
The VEC-121K is designed to tune the entire broadcast band. However, there
will be certain antenna lengths that will behave in unexpected manners at certain
frequencies. Also, because of the way the antenna and ground are coupled to the
receiver tuned circuits, they will also have some effect on the tuning range limits.
THEORY OF OPERATION AND SPECIFICATIONS
The tuning capacitor and coil form a parallel resonant circuit that tunes from
about 530-kHz to over 1.6 MHz. The antenna and ground are directly applied
across the resonant circuit. Thus, the set is optimized for use with short, high-