Vectronics VEC-102K - Manual (Page 32)

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The amplifier circuit provides sufficient output for moderate speaker volume. Miniature
speaker systems designed for "Walkman'' and similar personal stereo devices will plug
right into J2 or J3 and work very well. However, please remember that the amplifier is
specifically designed for headphone operation. If you prefer room-level speaker volume
for long listening sessions, we recommend an external amplifier as discussed below.
If you use personal FM, cassette or CD players, you probably also know all about those
compact "amplified speakers'' designed specifically to plug into the stereo jack of
compact personal stereos. These speaker setups have a built-in amplifier circuit and their
own separate batteries. Any of these devices should work well with your receiver. Radio
Shack carries a variety of amplified speaker pairs as well as several monaural utility
amplifiers. Even though stereo jacks are used, remember that the receiver audio output is
monaural.
An external amplifier can also be a rewarding do-it-yourself construction project. One-
half to 2 watts will provide generous and ample speaker volume. In fact, if building this
receiver has kindled your interest in building something on your own, you could get
started by duplicating the same LM386 audio circuit used in this receiver. Use the same
parts values and physical positioning as we did. The volume control may be omitted,
since you already can control the receiver's volume. The amplifier will operate on 6 to 15
volts DC. All needed parts are available at Radio Shack stores. You'll get plenty of
volume for any size of utility or communications speaker. (AUTHOR'S NOTE: I have
fully tested this use of a second identical LM386 IC circuit with speaker and can
recommend it highly to all who can't confine all this listening excitement to one or two
headsets!)
IMPORTANT: A monaural 1/8'' plug will "fit'' the receiver's stereo jacks. HOWEVER,
the plug must NOT be pushed all the way into the jack, because it will short out the audio
output. If you have reason to use a mono plug, insert it just far enough for the tip to make
firm contact with the first section inside the jack.
About the 5 Tuning Ranges of Your Receiver
The purpose of the following information is to give newcomers a general idea of what to
expect to hear in each of the 5 frequency ranges tuned by your receiver.
First, please understand that the frequency markings on the tuning dial can be only
approximate. They indicate the "general neighborhood'' of major frequency bands and
have an accuracy only within a few hundred KHz. (If you are wondering what it would
take to make the dial perfectly accurate, imagine an adjustable trimmer capacitor AND an
adjustable coil for EACH band! The process of making these many adjustments is called
alignment and also requires the use of frequency measuring equipment far more costly
than the receiver.)