Fine Tuning Control (R21)
This control is especially helpful in tuning CW and SSB signals.
DC Power Switch
While the purpose of the on-off switch is obvious, do remember
to turn your receiver OFF when not in use. Weakened batteries
will degrade receiver performance.
Volume (R17)
This potentiometer performs the normal function of any volume
control. For AM international broadcasts, and to conserve
battery life, you'll rarely need more than half of the available
gain offered by the TDA2611A audio IC.
Headphone Jack (J1)
This jack accepts standard 1/4" stereo or monaural plugs typical
of standard communications headsets. To use "Walkman" type
stereo headphones or mini-speaker systems, use a 1/4" stereo to
1/8" stereo adapter such as Radio Shack™ No. 274-367. This jack
may also be used to connect an external speaker (4 to 8 ohms)
of any size or power rating you wish. wired correctly during kit
assembly, the jack disconnects the receiver's internal speaker
when a plug is inserted. R28 and R29 slightly reduce the audio
level to the headphones and prevent monaural plugs from
causing a direct short to ground.
Antenna Terminal
The antenna wire (or feedline) is attached between the two flat
washers before tightening 10 to 20 feet of ordinary hookup wire
(also called "bell wire") provides good basic reception, even
when installed indoors. See the section on Antennas in this book
for more information.
Antenna Ground Connection
For casual listening to strong broadcast signals, a ground
connection is optional. However, a wire from this connector to a
ground rod or cold water pipe will reduce unwanted noise and
interference from nearby electrical devices or AC wiring and may
boost receiver sensitivity. You will find the ground connection to
be essential for reception above 9 or 10 MHz unless you are well
away from household AC wiring.
External 12-14 VDC Connection
This DC voltage connection for the audio amplifier circuit permits
the use of a wide variety of DC power sources. Some DC wall
adapters may work well, depending on their design Keep in mind
that some wall transformers only provide AC output voltage -
you MUST use a unit with 12 to 15 volts DC output.
1253 - 50
Using & Understanding
the Regeneration Control
In theory, your receiver's Regeneration Control adjusts the level
of feedback or self-oscillation of the FET detector section (Q2).
In practice, this control is like a "joystick" for optimizing receiver
performance. Your ability to handle this "joystick" saves you
many dollars over today's cost of receivers which perform similar
functions "automatically." You might even get more control over
receiver performance in varying situations than may be possible
with more expensive receivers. Once you know how to use it,
it's a fun control!
With the control turned fully to the left (counter clockwise),
the receiver is virtually silent. "Regeneration" begins at a
certain point as you turn the control clockwise. The exact point
varies not only from band to band but even as you tune within a
given band. Regeneration begins as an audible increase in back-
ground noise followed by a soft hiss. The hiss, or any signals
that may be on frequency, increases as you continue to turn
clockwise. If you go too far, the signal becomes distorted, or
the receiver begins to squeal (oscillate).
Always use the LEAST amount of regeneration necessary for
good reception of a given signal. The best reception of AM
shortwave broadcast signals occurs just before regeneration
begins. If you hear a whistle (carrier) along with an AM signal,
turn the control back slightly until the carrier disappears.
When there are many very strong shortwave AM broadcasts in
a given band, such as is common in the early evening,. you will
find it possible to tune them in one after the other with the
regeneration control set "way back" and requiring virtually no
adjustment. In other words, you would tune from station to
station just as if using any other type of shortwave set.
When the receiver is adjusted for good AM reception, CW signals
will sound like hisses. Advancing the regeneration control
slightly will bring in the familiar beeping associated with CW,
RTTY (radio teletype) or similar signals.
The regeneration control can also serve as a fine tuning control,
permitting slight adjustments of CW pitch for the most pleasing
sound, or best clarity in a SSB voice signal. After you've had
some practice with using the regeneration control, it will become
second nature, giving you a sense of real control over the
performance of your receiver.
1253 - 51
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