may be understood if you consider that when modulation is applied to the
transmitter’s microphone in the USB mode, the transmit)er’s output frequency
is increased whereas in the LSB mode the transmitter’s output frequency is de-
creased. The result in listening to the receiver is that when the MODE switch is
in the proper position (either USB or LSB), a true reproduction of single tone of
modulation will result, and if the tone is increased in frequency (such as a low-
pitched whistle a high-pitched whistle) you will hear the increase in the output
tone of the receiver. If the incorrect mode is selected, an increase in tone of a
whistle applied to the transmitter will cause a decrease in the résultant tone from
the receiver.
Thus when a vöice is used in place of a whistle or tone, in the proper listening '
mode the voice will be received correctly whereas in the incorrect mode, the
voice will be translated backwards and cannot be made intelligible by the voice
lock control. When listening to an AM transmission, a correct sideband is heard
in either mode since both upper and lower sideband are received.
Once the desired SSB mode has been selected, frequency adjustment may be
necessary in order to make the incoming signal intelligible, the VOICE LOCK
control allows the operator to vary frequency above and below the exact-center
frequency of the received signal. If the sound of the incoming signal is high or
low pitched, adjust the operation of the VOICE LOCK. Consider it as perform
ing the same function as a phonograph speed control. When the speed is set to
high, voices will be high-pitched and if set too low, voices will be low-pitched.
Also, there is only one correct speed that will make a particular record produce
the same sound that was recorded. If the record is played on a turntable that
rotates in the wrong direction (opposite sideband) no amount of speed control
(VOICE LOCK) will produce an intelligible sound.
An AM signal received while listening in one of the SSB modes will produce a
steady tone (carrier) in addition to the intelligence, unless the SSB receiver is
tuned to exactly the same frequency by the VOICE LOCK control. For simplici-
ty it is recommended that the AM modes be used to listen to AM signais.
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