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NOTE:
*
SW (including SSB and CW) reception is greatly affected by a
connected antenna. Therefore, to obtain the best possible
reception, proper antennas are required.
*
Some 3D-minute passage after power application will provide
essentially stable receiver-operation.
*
Turning the Display
Switch~
on and off may slightly drift the
displayed frequency.
SSB and CW Reception:
Set up the receiver in the same manner as SW2-8 reception, and
then follow the procedure below.
•
Set the AM Mode SwitchE» to CW/SSB.
•
Tune to the desired signal.
•
Rotate the BFO Pitch
Control~
until the received signal
becomes clear.
Note:
*
If received signals are too strong to clearly be heard,
rotate the AM RF Gain
Control~
counterclockwise until
distinct, pleasant sound is obtained.
*
In receiving two-way communication signals, a possible
difference between the two frequencies may demand
another BFO Pitch
Control~
adjustment.
ABOUT SSB AND CW
Single-Sideband (55 B):
In general, SSB corresponds to a modulated wave in the AM
Double-Sideband (DSB) signal. It is used for professional
purposes, amateur wireless, and it can be regarded as a special
type of AM wave.
Features:
1. In case of transmitting: All informations are transmitted with
a little energy and band width.
2. In case of receiving: Since there is no carrier, it is neces-
sary to use a special detection method.
AM (DSB) waves can be illustrated in a spectrum as in Fig. 17.
Electromagnetic wave (carrier) with two sidebands is transmitted
as a single group in an AM form. High frequency waves are
contained in the Upper-Sideband (USB) while the lower frequency
waves are in the Lower-Sideband (LSB). Voice and other informa-
tion are contained in the side bands but are not included in the
carrier; thus the carrier is not always necessary, and other
methods for transmitting the informations are considered.
One of these methods is SSB. Either the USB signal or the LSB
signal is transmitted and it depends upon individual customs.
Usually for amateur communication, LSB is used under 10 MHz.
SSB waves are generated by passing the AM wave through a
band-pass filter, then selecting either USB or LSB and sending
the signal through the transmitting antenna. In receiving SSB
(USB or LSB) waves on an ordinary AM receiver, it would not be
possible to hear a transmitted voice unless a special alteration
was made at the detection stage; either to construct the carrier
-8-
and detect the AM after adding the SSB or to use the switching
method (product detection) on the frequency of the carrier for the
SSB. The latter method has less distortion, and it is used in this
receiver.
t
Strength of the
frequency
component
Carrier
Lower-Sideband
(LSB)
Upper-Sideband
(USB)
-----I~~
Frequency
Fig. 17
Continuous Waves (CW):
In practice, it is used to transmit Morse code signals by inter-
mitting the carrier, but it is difficult to hear the sound even after
AM detection. Using the detection circuit of the SSB, the inter-
mitted sound can be heard by product-detecting the carrier and
by varying the frequency slightly.
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