Sony ICF-SW77 - Manual Tuning Procedures; How to Tune In a Station Manually; To change the selectivity; To activate the synchronous detection

Manual Tuning
Use manual tuning when you do not know the frequency of
the station you want to tune in, or when you want to tune in a
station more precisely after scan tuning (page 20).
Notes:
• When the upper or lower limit Ol the band Irequency (FM or AM) is reached,
the frequency no longer changes even if you turn Ihe DIAL TUNE/JOG dial
lurlher.
How to Tune In a Station Manually
1 Set POWER/LOCK to POWER.
2 Press ON/OFF.
The indications on the frequency display appear.
3 Select the desired band by pressing FM or AM.
For AM (SW, MW, or LW) reception, select the required AM
mode (See the next section.)
4 For AM reception, select the tuning interval (fast or slow) by
pressing FAST/SLOW.
Each time you press it. the tuning interval changes alter¬
nately.
FAST (no indication): 1 kHz SLOW: 50 Hz
5 Turn the DIAL TUNE/JOG dial to tune in a desired station,
Turn the dial clockwise for higher frequencies and counter¬
clockwise for lower frequencies.
. For AM (LW. MW. and SW) reception in SYNC U.SYNC L. USB. or LSB'CW,
be sure to set the tuning interval to SLOW and turn the DIAL TUNE/JOG dial
slowly.
• When the DIAL LOCK switch is set 10 the direction ol the arrow, you cannot
change Ihe frequency by turning DIAL TUNE/JOG
How to Select the AM Mode
Select the appropriate AM mode according to the broadcast
receiving conditions.
Press the MODE buttons.
Saudi Arabian model: WIDE/NARROW, SYNC U, and SYNC
L.
Models for other countries: WIDE/NARROW, SYNC, and
SSB.
The selected AM mode appears on the Irequency display.
Note
When you select "SLOW", the tuning interval will be 50 Hz, but
the frequency is displayed in 100 Hz step
18
To change the selectivity
Press WIDE/NARROW and display WIDE or NARROW
WIDE: Normally set to this mode for wider selectivity
NARROW: If reception is interrupted or noisy, set to this mode
for narrower selectivity Reception will be improved
To activate thesynchronous detecttorw
Press SYNC and display SYNC U or SYNC L.
Select either SYNC U or SYNC L which best reduces signal
interference or distortion due to fadings.
If neither of the two is effective or if the sound gets worse,
press SYNC again to cancel this mode. The SYNC indication
disappears.
When you select SYNC U or SYNC L
The SYNC LOCK indication appears on the display. If this indication does not
appear, it shows that the synchronous detection cannot be performed because
the signal is too weak.
To activate the SSB (SinglefSide Band) mode
Press SSB and display USB or LSB/CW.
USB: For USB (Upper Side Band) reception.
LSB/CW: For LSB (Lower Side Band) or CW (International
Morse Code) reception.
About SSB (Single Side Band) and CW (Continuous Wave)
SSB is very popular among ham and business radio and will be found on all of
the amateur bands because of its signal intelligibility. This results from that it
transmits signals with half bandwidth of DSB (Double Side Band)
In general. SSB transmissions up to t0 MHz employs LSB modulation, and
those above this frequency uses USB.
CW is also popular among ham and business radio. In CW transmission, the
amplitude of a carrier is not modulated while that of other system is modulated
CW conveys information by interrupting a carrier using Morse code. It can be
heard as a beat sound only with the unit equipped wilh the BFO circuits To
understand the information transmitted by CW, you need to team ihe Morse
code.
1 Synchronous detection extracts one side band free from interference out of
the DSB signals. The circuit takes the carrier wave out of the signals, and
provides them with the synthesized signal of exactly the same frequency and
phase.
2 Fading is a phenomenon in which the sound gets louder and lower in turn If
occurs because the signal from the station arrives by two or more different
paths
What is synchronous detection?
There are two big problems in AM reception: distortion due
to fading and interference from adjacent stations. The syn¬
chronous detection is effective in solving these problems.
Distortion due to fading is caused by over-modulation,
which occurs when a carrier component of the received
signal is attenuated on the way. In this receiver, a pure
carrier frequency with no level variation, perfectly synchro¬
nized with the original carrier, is generated in the synchro¬
nous detector circuit and is mixed with the received signal
to compensate the attenuated carrier component In this
way, distortion is remarkably reduced.
On the other hand, AM (LW, MW, and SW) broadcasting
generally uses double-sideband transmission, in which
modulated signals are transmitted using both the upper
and lower sidebands (USB and LSB). In most cases, one
of the sidebands is affected by interference from adjacent
stations (beats). In the synchronous detector circuit, one of
USB and LSB can be received. This allows clear reception
without interference from adjacent stations.
. Interference from
adjacent station.
Only this side is
received.
ICF-SW77