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10

RECEIVING SSB SIGNALS 

 

There are four types of signals presently used for communications: FM, AM, USB 

and LSB. When the MODE switch on your unit is placed in the AM position, only 
standard double-side band and in FM position, only frequency deviation, full carrier 
signals will be detected. An SSB signal may be recognized while in the AM or FM 
mode by its characteristic "Donald Duck" sound and the inability of the detector to 
produce an intelligible output. The USB and LSB modes will detect upper sideband and 
lower sideband respectively, and standard AM signals. 

 
SSB reception differs from standard AM reception in that an SSB receiver does not 

require a carrier or opposite side band to produce an intelligible signal. A single-side 
band transmitted signal consists only of the upper or the lower side band and no carrier 
is transmitted. The elimination of the carrier from the AM signal helps to eliminate the 
biggest cause of whistles and tones heard on channels that make even moderately strong 
AM signals unreadable. Also, SSB takes only half the space of an AM channel, 
therefore two SSB conversations will fit into each channel, expanding the 40 AM 
channels to 80 SSB channels. The reduction in channel space required also helps in the 
receiver because only half of the noise and interference can be received with 100% of 
the SSB signal. 

 
An SSB signal may be received only when the listening receiver is functioning in the 

same mode. In other words, an upper side band signal (USB) may be made intelligible 
only if the receiver is functioning in the USB position.  

 
If a lower side band (LSB) signal is heard when the receiver is in the USB mode, no 

amount of tuning will make the signal intelligible. The reason for this may be 
understood if  you consider that when the modulation is applied to the transmitter's 
microphone in the USB mode, the transmitter output frequency is increased whereas in 
the LSB mode the transmitter's output frequency is decreased.  

 
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 a single tone of modulation will 
result, and if the tone is increased in frequency (such as a low-pitched whistle or 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 resultant tone from the receiver. 

 

 

11

Thus when a voice 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 COARSE/FINE control. 
When listening to an AM transmission, a correct side band is heard in either mode since 
both upper and lower side bands are received. 

 
Once the desired SSB mode has been selected, frequency adjustment may be 

necessary in order to make the incoming signal intelligible. The COARSE/FINE control 
allows the operator to vary frequency above or below the exact frequency of the 
channel. If the sound of the incoming signal is high or low pitched, adjust the operation 
of the COARSE/FINE.  

 
Consider it as performing the same function as a phonograph speed control. When the 

speed is set too high, voices will be high-pitched and if set too low, voice 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 is rotated in 
the wrong direction (opposite side band) no amount of speed control (COARSE/FINE) 
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 COARSE/FINE control. For simplicity, it is recommended 
that the AM modes be used to listen to AM signals.  
 

Summary of Contents for DX 98VHP

Page 1: ...z O FF SWR 1 1 5 3 2 S 1 0 5 3 9 7 SET 40 20 60 dB MAX 200 150 100 50 25 PO 0 PA B IG R IG S E R IE S DX 9 8 V HP F D O FF N B A N L 1 TABLE OF CONTENTS PAGE CHAPTER 1 Specifications 2 CHAPTER 2 Insta...

Page 2: ...th the radio in the location where the radio is to be installed Make sure nothing will interfere with either the radio or the mounting bolts Mark and then drill holes for the mounting bracket 2 Most r...

Page 3: ...e and be able to handle at least 4 watts When the external speaker is plugged in the internal speaker is disconnected PUBLIC ADDRESS To use the Public Address PA function first connect an external spe...

Page 4: ...ue Therefore it is ideal for switch and control recognition day or night 16 BAND SELECTOR This switch is used to select the band 7 17 PWR SWR RB SWITCH When in the RB position the radio transmits an a...

Page 5: ...th and speak clearly in a normal voice This transceiver comes complete with a low impedance dynamic microphone B PROCEDURE TO RECEIVE 1 Be sure that power source microphone and antenna are connected t...

Page 6: ...eased whereas in the LSB mode the transmitter s output frequency is decreased The result in listening to the receiver is that when the MODE switch is in the proper position either USB or LSB a true re...

Page 7: ...be used is provided with pre cut leads they must be revised as follows 1 Cut leads so that they extend 7 16 beyond the plastic insulating jacket of the microphone cable 2 All leads should be cut to th...

Page 8: ...he connections to pin 1 and 3 are made first and then the connections to pins 2 and 4 Use a minimum amount of soldering and be careful to prevent excessive solder accumulation on pins which could caus...

Page 9: ...16 MEMO 17 MEMO...

Page 10: ...n of the symptoms This is important because it will help the technician who works on your radio to locate your problem Intermittent problems are easily overlooked so be sure to give as much detail as...

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