Ten-Tec 1253 Assembly And Instruction Manual page 52

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.
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