Walter Drake SW8 - Manual (Page 18)

CARRIER
LSB USB
interference from
adjacent station
12 Getting Started, continued
alternate sideband if desired. When AM/SYNC has been
activated, moving the main tuning knob will cause the
SYNC circuit to momentarily disengage (indicated by
‘SYNC’ flashing), then back on again when tuning has
stopped. AM SYNC does not function on the AIR band,
and will not operate properly on intermittent transmis-
sions such as those encountered on CB radio bands, for
example. For those types of transmissions, use the AM
mode. Press the
AM
SYNC
4
button to turn the synchronous
detector off before selecting LSB or USB modes.
SSB OPERATION
Tuning in a single sideband (SSB) signal can be somewhat
frustrating for the first time listener. In either of the
SW8’s SSB modes, LSB (lower sideband), or USB (upper
sideband), the receiver will select the 2.3 kHz bandwidth
automatically (the SW8 may be programmed to NOT
automatically select a bandwidth. Refer to 'Automatic
Bandwidth Setting With Mode Selection DISABLE
(ENABLE)' in the 'Special Use Features and Functions'
section of this manual). Generally, LSB is used below 10
MHz and USB is used above 10 MHz. When initially
tuning in the desired station, tune slowly. If the station is
unintelligable, try the other sideband, again tuning slowly.
A station tuned in on the wrong sideband is totally
unreadable but a station mistuned on the correct
sideband may sound like ‘Donald Duck’. Further tuning
will result in a more normal voice pitch.
FM OPERATION
FM reception is perhaps the easiest mode to use on the
SW8. The AGC and BANDWIDTH settings are not used
in FM. In fact, attempting to activate these buttons will
result in an ‘ERROR’ beep. All FM stations in the U. S.
end in an odd 100 kHz, i.e., 97.7 MHz, and are spaced
200 kHz apart. The SW8 has the ability to tune in 20 kHz
steps to allow tuning in between stations to help elimi-
nate interference to weaker stations that could be
covered up by stronger adjacent stations. Additionally,
when headphones are used, true stereo reception is
possible. The front panel
S T
annunciator will light
when a stereo station is tuned in with the stereo head-
phones plugged in. The SW8 will automatically switch to
stereo and provide left and right audio from the head-
phone jack only. If the headphones are removed while
listening to a stereo broadcast, the SW8 reverts to
monaural audio from the internal or external speaker.
AGC OPERATION
The SW8 provides the ability to select a Slow or Fast
AGC setting. Either of the two settings will permit
automatic control of the receiver’s gain thereby produc-
ing a constant audio output free of distortion. Generally,
the Slow AGC setting is preferred for reception of AM
and SSB signals. The Fast AGC setting allows more rapid
automatic receiver gain adjustment to quickly fading
signal levels.
The AGC does not function in the FM mode.
Display
Resolution
100 Hz
100 Hz
100 Hz
10 kHz
100 Hz
Mode
Broadcast
Band:
AM
Shortwave
Band:
AM
USB, LSB
FM
AIR
Tuning
Resolution
100 Hz
100 Hz
50 Hz
20 kHz
100 Hz
10 kHz/9 kHz
5 kHz
5 kHz
100 kHz
25 kHz
Select LSB to
receive this
side only
FREQUENCY RESOLUTION
The SW8 tunes in the following steps:
FRONT PANEL LOCK (UNLOCK)
All keyboard entries, display settings, and entries from
the tuning knob can be locked if desired. First, be sure
the SW8 is not in SCAN. Press and hold the
F
button. The LOCK annunciator will light indicating the
front panel controls are locked out. Power ON/OFF will
still function as well as volume and tone controls. Press
and hold the
F
button to unlock.
AM SYNCHRONOUS OPERATION
For general tuning and listening, normal AM is best. If,
however, the received signal sounds distorted, or
interference from adjacent stations is present, AM
synchronous should be engaged. The synchronous
detector in your receiver can greatly reduce the severe
audio distortion that can occur due to signal fading. The
detector also permits selectable tuning to either the
upper or lower sideband portion of an AM signal. Since
most all AM (LW, MW and SW) broadcasting generally
uses double-sideband transmission, detection of either of
the two sidebands results in full reception of the trans-
mitted information. The selectable sideband tuning and
detection not only aids reception by permitting tuning to
the stronger or less distorted sideband, but also permits
rejection of the sideband nearer to the interfering
signal(s). For Example:
The synchronous detector will lock to the strongest
signal that is within the IF passband when it is activated.
Most of the time, the strongest signal will be the carrier
of the desired signal. First, be sure the main tuning is set
to within 1 kHz of the desired station’s transmitting
frequency. Press the
AM
SYNC
4
button to activate synchro-
nous operation. If adjacent channel interference or any
other undesired signal is sufficiently strong, the synchro-
nous detector may lock to it instead. In that case, press
the
AM
SYNC
4
button to turn the synchronous detector off
and repeat the tuning process. For severe cases of
fading, set the audio bandwidth to 4 kHz. If interference
is present, press the SSB button to select the sideband
with the least interference. If the interference is suffi-
ciently severe to prevent reception, select a narrower IF
bandwidth and retune to the desired signal. After
reception is obtained, select a wider bandwidth and/or