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Radio Shack PRO-79 owner manual Avoiding Image Frequencies

Models: PRO-79

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AVOIDING IMAGE FREQUENCIES

To turn on the keylock, hold down for about 3 seconds un-

til the scanner beeps three times and appears. To turn it

off, hold down for about 3 seconds until the scanner beeps

three times and disappears.

AVOIDING IMAGE FREQUENCIES

You might discover one of your regular stations on another fre- quency that is not listed. It might be what is known as an image frequency. For example, you might find a service that regularly uses a frequency of 453.275 also on 474.675 MHz.

To see if it is an image, do a little math.
Note the new frequency	474.675
Double the intermediate frequency of 10.7 MHz	(21.400)
and subtract it from the new frequency	–21.400
If the answer is the regular frequency	453.275
then you have tuned to an image.

Occasionally, you might get interference on a weak or distant channel from a strong transmission 21.4 MHz above or below the tuned frequency. This is rare, and the image signal is usually cleared whenever there is a transmission on the actual frequen- cy.

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Radio Shack PRO-79 owner manual Avoiding Image Frequencies

Contents

PRO-79 200-Channel VHF/Air/UHF Handheld Scanner Owner’s Manualillus - show front of product FEATURES Page FCC NOTICE SCANNING LEGALLY CONTENTS Special Features TroubleshootingCare and Maintenance SpecificationsPREPARATION INSTALLING BATTERIESCautions USING VEHICLE BATTERY POWER USING AC POWERCautions CHARGING RECHARGEABLE BATTERIES CautionsCONNECTING AN ANTENNA Connecting the Supplied AntennaConnecting an Outdoor Antenna CautionsCONNECTING AN EARPHONE HEADPHONES Listening SafelyCONNECTING AN EXTENSION SPEAKER Traffic SafetyUNDERSTANDING YOUR SCANNER A LOOK AT THE KEYPADNumber KeysA LOOK AT THE DISPLAY ALErtBANK C-ErrPage WirEd UNDERSTANDING BANKSChannel Storage Banks SCANService Banks Fire/PoliceAmateur Radio MarineGroup Frequency Range MHzChannel Frequency MHzFrequency MHz Channel156.9250 MONITOR MEMORIES OPERATION RESETTING/INITIALIZING THE SCANNERTURNING ON THE SCANNER/SETTING VOLUME AND SQUELCH Resetting the Scanner Initializing the ScannerSTORING KNOWN FREQUENCIES INTO CHANNELS Searching the Service Banks FINDING AND STORING ACTIVE FREQUENCIESUsing Direct Search To pause the search, press or . To resume search- ing, hold down or Listening to a Monitor Memory USING MONITOR MEMORYMoving a Frequency from a Monitor Memory to a Channel SCANNING THE STORED CHANNELS TURNING CHANNEL-STORAGE BANKS OFF AND ON MONITORING A STORED CHANNELLISTENING TO THE MARINE BANK CLEARING A STORED CHANNELLISTENING TO THE WEATHER BAND WX Alert SPECIAL FEATURES DELAYLOCKING OUT CHANNELS OR FREQUENCIES Locking Out ChannelsReviewing Locked-Out Frequencies Locking Out FrequenciesRemoving Lockouts From All Frequencies USING PRIORITY Removing Lockouts From All Frequencies in All Service BanksUSING THE KEY LOCK USING THE DISPLAY BACKLIGHTTURNING THE KEY TONE ON AND OFF AVOIDING IMAGE FREQUENCIES A GENERAL GUIDE TO SCANNING GUIDE TO FREQUENCIESNational Weather Frequencies Birdie FrequenciesGUIDE TO THE ACTION BANDS Typical Band Usage MHzPrimary Usage VHF BandBAND ALLOCATION ServicesAbbreviations HIGH FREQUENCY HF - 3 MHz- 30 MHz 10-Meter Amateur Band 28.0-29.7 MHz VERY HIGH FREQUENCY VHF - 30 MHz- 300 MHzVHF Low Band 29.7-50 MHz -in 5 kHz steps 6-Meter Amateur Band 50-54 MHzVHF High Band 148-174 MHz ULTRA HIGH FREQUENCY UHF - 300 MHz- 3 GHzU. S. Government Band 406-420 MHz 70-Centimeter Amateur Band 420-450 MHzFREQUENCY CONVERSION Low Band 450-470 MHzTROUBLESHOOTING SQUELCH is notCARE AND MAINTENANCE Audio Output Power 10% THD SPECIFICATIONSIF Interference Ratio 10.7 MHz 6 Volts DC, 4 AA Batteries Page RadioShack A Division of Tandy CorporationFort Worth, Texas Limited One-Year Warranty