Controls And Functions - Carver TX-11b Manual

Controls & Functions
Frequency Display
Signal Strength Indicator
Stereo Indicator LED
Tuning
Down Up
Power On/OFF
FM AM I
IF Band
Auto Tuning
Multipath Reduction (FM)
Noise Limiter (AM)
L output (white)
Noise Reduction (FM)
RF Gain (AM)
+ 12dB
Antenna inputs
Power
The POWER switch on the lower lefthand side of the TX-11 b turns
the unit on or off. When you power up, the tuner will be tuned to the
same station you were listening to before power was switched off.
R output (red)
Manual Tuning
Tuning
What Happens When You Tune the
TX-11b?
The first in the chain of events that go on inside a tuner is the frequency
tuning itself. Here the Carver TX-11 b uses a phase-locked loop with
digitally synthesized tuning controlled by a 4-bit microprocessor.
What happens is this: a crystal-controlled oscillator runs at an exact
frequency which is then divided down. Meanwhile, a local oscillator
is tuning to the station's frequency which is lowered by a
programmable divider. The phase of the two reduced frequencies is
compared, and once they match exactly, the LOCKED light goes on
and phase-locked loop takes over. The phase-locked loop is a circuit
that compares the phase of the tuned frequency and the reference
frequency continuously. If the tuned frequency drifts, the comparator
brings it right back.
With the TX-11 b on, press the Auto tuning momentary switch. The
Auto LED will go out, and you can press either the DOWN or UP
control buttons to change frequencies. One push gets you a change
of 0.1 MHz. Holding the button results in a more rapid change of
frequencies. Stop when you get to a station's exact frequency. If
you're not quite sure what the exact frequency is, use the SIGNAL
STRENGTH INDICATORS and "LOCKED" INDICATOR L.E.D.
If you try to tune lower or higher than the frequency limits (87.5 MHz
low, 108 MHz high), the tuner will not change frequencies; you'll have
to push the other tuning button.
The TX-11 b's threshold circuitry is defeated during manual tuning;
this will allow reception of a weak or extremely distant station. More
about this in a bit.
Automatic Scan Tuning
Make sure the AUTO tuning LED is on. Then press either the UP or
DOWN button. The tuner will change to the next higher or lower station
with a signal strong enough to defeat the muting circuitry of the TX-
11 b. The automatic interstation muting circuit is engaged during
tuning (in both MANUAL and AUTO modes). If you hold the UP or
DOWN buttons down during the auto tuning, the tuner will skip past
stations until you let go.
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