Realistic PRO-16A User's Manual
Contents
1. Scanning Monitor Receiver WHF 399 658 026 174 M az Je 400 612 Milz PRO 164 a PLEASE READ BEFORE USING THIS EQUIPMENT FREALISTIC CAT NO 20 165 CUSTOM MANUFACTURED FOR RADIO SHACK BE DIVISION OF TANDY CORPORATION Your PATROLMAN 16 scanning receiver is a completely tran sistorized VHF UHF superheterodyne receiver using dual conversion for the VHF bands and triple conversion for the UHF band It is capable of automatically scanning sixteen crystal controlled chan nels Some special features are four ceramic filters channel lock out circuit skipper circuit AFC circuit for UHF band scan delay circuit switchable and AC or DC operation It is designed for use in the narrow band FM channels of public service communications VHF and UHF band police fire civil defense radio telephone forestry and weather service plus many other industrial radio services and the 2 meter radio band upper end These and many other services share this band of frequencies from 30 to 50 MHz 148 to 174 MHz and 450 to 512 MHz The PRO 16A features both high sensitivity and selectivity and a sophisticated circuit which includes 10 7 MHz and 445 kHz ceramic filters to reduce or eliminate adjacent channel or strong signal inter ference Such interference is often experienced when operating in urban and metropolitan areas or where very strong and2. She 42 83 Ke Bes BE rej 02 TPS lin Grex f Stax cF i 23 ay Fol C33 470P ED z gE S Y 8 Q4 3 9 28 os Br 47 ELK 18 E c eF 5 1 06 NS Ep 8 158 8 z ate X S lao El N 9 8 onol 8 1 aiio Baro lav L 1 QIO 2SK30A C 011 12 25 573 5 RF AF GE I98 4504 C40 47 16 amp R33 8 2K 01 3 5449510 Q4 250373 Q5 2SC684 B 06 9 25C394 Y 101 2 MX D3 50 D53 084 4 80 SPEAKER e 50K A VOLUME C52 220 16 x 58 5 t 011 SN 519 59 t bt 10 26 41 Tes 7402 T 97 31 2 i9 3 8 VR3 50KB SOUELCH 5 07 8 28 372 0 8 E E 5 ej 41 2 28C1117 03 25 78410 NIS 100 Rag E 1 8 T 8 LS XD 47 16 1 8 SIE 35 1 wor 3 9
3. 38 0499 RAL IK p Leo sel os je 050 CRYSTAL 1 PLi e 924 5 of ES io s25 pas 1917 24 CHANNEL LOCK OUT EDD SWITCH REMARKS 1 RESISTANCE VALUES IN OHMS 1000 M 1000000 2 CAPACITANCE VALUES IN MF 3 T TANTALUM CAPACITOR 4t MI MYLAR CAPACITOR ALL VALUES AND RATINGS ARE SUBJECT TO CHANGE FOR IMPROVEMENT WITHOUT NOTICE C_ THIS SYMBOL INDICATES DC VOLTAGE MEASURED BY V T V M IN FOLLOWING CONDITION HIGH BANO CH 2 MANUAL OPERATED VOLUME MINIMUM POSITION AND SOUELCH CONTROL OUT POSITION THIS SYMBOL INDICATES VOLTAGES WITH UHF RECEPTION FOR CSA MODEL ONLY WHT 120 AC 60Hz 4A6 3500 XC RADIO SHACK LIMITED WARRANTY This equipment is warranteed against defects for 1 year from date of purchase Within this period we will repair it without charge for parts and labor Simply bring your sales slip as proof of purchase date to any Radio Shack store Warranty does not covertransporta tion costs Nor does it cover equipment subjected to misuse or accidental damage This Warranty gives you specific legal rights and you may also have other rights which vary from state to state We Service What We Sell RADIO snack A DIVISION OF TANDY CORPORATION U S A FORT WORTH TEXAS 76102 CANADA BARRIE ONTARIO CANADA L4M 4W5 TANDY CORPORATION k AUSTRALIA BELGIUM
4. IM 196 C54 oim ES 116 ce Sx 052 r 2 R54 i es 37 s 52 A S i8 81247 E aag 18 181 is 51 21 18 ps8 gto ox gia su s le 8 a j8 2 i W QIO 29C387A 2SC3z8 051 52 IN6O i ue 08 1 PL1 Imt em On ie 74145 1 7495 16 BAND SWITCH 1 81 16 PL2 657456 014 2sc789 0 014 25 1173 0 03 02210A 5 D4 8 151885 o tiere e R50 4711 2 C57 220 25 EXT POWER JACK SCAN RATE DCI 15 NEG GND ONLY lt 24 bes R29 LLL 54 D 526 027 R30 IK ssl T Bos 5 029 R3I IK Rel 39K D35 R34 IK rj 9 S9 D36 D37 R35 IK 01 12 250373 533 MANUAL SWITCH 34 7 DELAY SWITCH IR MANUAL SWITCH 01 2 6 N D3 5 7 IN6O x SCAN SWITCH p o SIO 38 o amp C35 R37 IK 512 OF af 0 039 fy mae IK d E 81 oF 044 b R39 IK pto salo D46 047 R40 IK 515 oH C40 D42 RIE IK sialo 656
5. Q7 Qe Q9 Qu Oz ze e CRYSTAL Fron Ja Ed SQUELCH Power PHONE JACK H 5 3 L SWITCI 8 BUFFER CRYSTAL TRIPLER NOISE AMP EN RIPPLE FILT 1 RECTIFIER MIXER d AMP DETECTOR B QU 04 L 050 TO LAMP Ona D Da Dz 120V 60Hz UHF FRONT END GE 190 5005 x SM n REGULATED DC VSTAL Fra pem POLARITY WER SUPPLY 98 CRYSTAL Figg XT Ay PROTECTOR SWITCHING CIRCUIT Os 12 15 DC NEG GND ONLY LOCAL OSC DELAY AMP FOR VHF SCANNING GENERATOR Hu CR f f B 1 LOCAL OSC n INDICATOR SKIPPER FOR_VHF LAMP Low BAND 0 1 5 Qe 07 PL 1 6 Dt 04 1 BUFFER AMP as ads Qs Ds Qi 0 erene Di9 Ds0 SCAN RATE osc GE 198 4508 Q7 Qe 1 1 4 PRIORITY GENERATOR Q9 0 LOGIC PC B GE I9B 4512 ANT JACK UHF ANT JACK 42 R2330 Qi 2 28C535 B T2 RI 68K LEEREN mL SCHEMATIC DIAGRAM Eas pi CHEN IF AMP GE I 8C 4425 R30 470 i DI 2 i t mg GE mm 470K ED
6. There are many possible mounting locations on a car Three of the most popular locations for monitor antennas are shown below ROOF MOUNT The antenna is mounted in the center of the roof This position is considered the best by many because it generally results in better reception than the other locations Radio Shack s Hi VHF UHF Mobile Mount Catalog Number 20 177 comes complete like all our monitor antennas with low loss coax cable COWL MOUNT If you would rather not cut a hole in the center of your vehicle s roof you may prefer this location Ask about our 20 016 Cowl Mount antenna which is especially designed for Hi Low VHF monitoring For UHF use 20 183 REAR DECK Installation in this location may result in less noise because it is further from the engine Your Radio Shack salesman will help you select the antenna which is best for you Keep the following points in mind when installing your mobile antenna 1 Mount the antenna as high as possible 2 Mount it rigidly so it will remain vertical while in motion 3 Mount as far as possible from the engine compartment MOBILE NOISE SUPPRESSION This receiver is very sensitive and will pick up signals that are extremely weak With this extreme sensitivity you will find that the receiver will amplify weak signals along with any noise that may be present When operating a receiver in a vehicle you will find that the vehicle generates noise and this noise can become
7. U K 280 316 VICTORIA ROAD PARC INDUSTRIEL DE NANINNE BILSTON ROAD RYDALMERE N S W 2116 5140 NANINNE WEDNESBURY STAFFS WS10 7JN Printed in Japan
8. an antenna to this jack Use an antenna such as Catalog Number 20 161 indoor opera tion UHF Antenna Jack connect an external antenna to this jack for UHF reception Use an antenna such as Radio Shack Catalog Number 20 451 indoor operation TAPE OUT Jack for recording off the air you can connect your tape recorder directly to this jack Headphone External Speaker jack is for plugging in a headphone or an external speaker Use it for private listening or in areas where back ground noise is excessive in factories at the scene of an accident or fire in a vehicle etc If you want a remote speaker plug it in here Connecting a plug to this jack automatically disconnects the internal speaker Mounting Bracket this universal type bracket is provided for quick and easy installation in a vehicle boat or for permanent installation in a base station situation Line Cord for AC operation plug into a source of 120 volts 60 Hz AC power Crystal Program Switch Compartment remove screws to open the case bottom to install or replace crystals DC Power jack is for connecting an external source of 12 volts DC negative ground This will permit you to use the PRO 16A in a vehicle or boat VOLUME SQUELCH SCAN PRIORITY CHANNEL LOCK OUT BUTTONS Power Control RATE INDICATOR LIGHTS Control Control PRIORITY PROGRAM PATROLMAN PRO 16A 3 BAND 16 CHANNEL AUTO SCANNING RECEIVER 1 MANU
9. frequency range FREQUENCY RANGE CHANNELS OF OPERATION FREQUENCY COVERAGE VHF 6 or 8 MHz for maximum sensitivity 40 MHz 3 MHz 153 MHz 4 MHz UHF 30 MHz for maximum sensitivity 480 MHz 15 MHz Better than 1 V for 20 dB quieting 213 5 kHz 6 dB 225 kHz 50 dB SENSITIVITY SELECTIVITY ADJACENT CHANNEL REJECTION SPURIOUS REJECTION VHF IMAGE REJECTION VHF UHF VARIABLE SCANNING SPEED PRIORITY CYCLE RATE DELAY TIME MODULATION ACCEPTANCE AFC ACTION UHF FREQUENCY 65 dB 25 kHz Greater than 50 dB Greater than 35 dB Greater than 20 dB 10 to 20 channels second 0 8 to 1 5 seconds 1 5 to 3 seconds 7 kHz Greater than 4 kHz 44 MHz UHF Band only 10 7 MHz and 455 kHz Ceramic filter 10 7 MHz and 455 kHz Variable from less than 1 microvolt 2 watts maximum Standard HC 25 U 3rd overtone 2 x 4 6 3 x 10 cm oval speaker 120 volts 60 Hz 12 watts max DC 12 15 volts Negative Ground only 10 watts maximum FILTER SQUELCH SENSITIVITY AUDIO POWER CRYSTAL REQUIREMENTS BUILT IN SPEAKER POWER REQUIREMENTS PREPARING FOR USE To use your 16 you must do three things Connect power Install from 1 to 16 crystals Connect an antenna To make a quick check you can just connect the Line Cord to a source of 120 volts 60 Hz AC power If you intend to use a 12 volt source you must connect the 12 volt DC power plug wires
10. hour a day in many parts of the country If you are using a crystal set to one of the two channels assigned 162 55 or 162 40 MHz your PRO 16A will automatically lock in on that channel since the broadcasts are continuous To prevent automatic locking set the channel lock out button for that channel to the off position button out When you want a weather report set the Lock Out Button to the position press in for that channel areas where two stations are close to each other one will use 162 55 and the other will use 162 40 MHz Check with your local FCC office or the Weather Bureau for the frequency used in your area MAE ANT JACK MAINTENANCE The PRO 16A is a ruggedly built electronic unit with all parts conservatively rated However you should treat it with care don t subject it to excessively rough handling You will find it will give you long life if kept free from dirt and excessive humidity BLOCK DIAGRAM RF AF P C B GE ISB 4504 FILTER 1 0 CERAMIC FILTER 455KHz IF AMP MIXER IF Qa 7 09 UHF ANT JACK Je i IBC 4425 TAPE QUTJACK 5 4 MIXER 06 AUDIO e AMPLIFIER Ic t SPEAKER VOLUMI E amp LOCAL osc DC AMP SQUELCH AUDIO 144MHz UHF BANDI FOR AFC PRE AMP 547 MHz
11. of the PRO 16A which should be attempted only by qualified Electronics Service Technicians who have adequately calibrated precision test equipment TYPES OF SIGNALS YOU LL BE ABLE TO MONITOR Your community is alive with action action which is constantly being reported on the air waves And your PRO 16A will automatically scan the air waves to bring you that action your police force at work a fire truck on a mission Sheriff s department State police the National Weather Service Ham Radio operators highway and other emergency type services some industrial services some transportation services taxi trucks railroad plussome Government services Lots of things are going on that most of us just are never aware of But with the right frequency crystal in your PRO 16A you can monitor such exciting signals You ll have to do a little investigating in your com munity to find out what services are active and on what frequencies You will find one of our books to be very interesting and helpful in this area REALISTIC GUIDE TO POLICE FIRE AND AIRCRAFT RADIO What to listen for and where That is a little difficult for a specific answer Each area of the country can and will use different channels All we do is give you some general pointers and then let you take it from there Find out if there is a local club which monitors these frequencies Often a local electronics repair shop that does work on the equipment can give yo
12. very objectionable Mobile operation will not be as quiet as base station operation but steps can be taken that will greatly improve the noise situation ELECTRICAL SYSTEM Generally speaking noise can be generated by any device or connec tion that carries electrical current Any device that generates a spark should also be suspected Bypass any suspected wire to ground with a high quality 1 uF coaxial capacitor A very common source of noise is the generator or alternator This type of noise will sound like a musical whine and will also vary with speed of the engine Generator and alternator noise can usually be reduced by connecting a coaxial type capacitor from the armature terminal to the metal case IGNITION SYSTEM The ignition system is the most common source of noise This noise can be identified by the fact that its speed varies with the engine speed Ignition noise will sound like a series of popping sounds while the engine is idling and will speed up to a buzzing sound as engine speed is increased There are a number of things that can be done for this type of noise 1 Use radio suppression type ignition wire and resistor spark plugs 2 Check high voltage wiring for leakage cracks etc Replace any old wiring 3 In extreme cases obtain an ignition noise suppression kit it should shield all ignition wiring This will provide maximum noise suppression OPERATION After power and antennas are connected
13. AL SCAN MANUAL DELAY ON OFF SELECTOR Button Button Button VHF UHF TAPE OUT HEADPHONE DC POWER AC LINE ANT JACK ANT JACK JACK EXT SPEAKER JACK CORD JACK CAUTION PREVENT ELECTRIC ninety h MAT Hcenue mnurornn INSTALLATION A good installation will make the most of the PRO 16A s capabilities Don t loose any of the tiny signals by using an inadequate antenna or poor quality lead in Use an antenna of correct length and a good quality foam coaxial cable The antennas that you choose and how you install them will have a great effect on how well your receiver will work Your PRO 16A is designed to utilize two antennas one for VHF and one for UHF BASE INSTALLATION For a base installation you only need two things The most important is a good antenna For superior reception it is vital that you use the best antenna you can afford and then mount it properly We recom mend a Radio Shack Catalog Number 20 182 for superior UHF reception and a 20 015 for VHF reception Use RG 58 U coaxial lead in cable to assure maximum transfer of the tiny signals Use Motorola adapter plugs as appropriate 278 208 The only other thing you need to do is connect the line cord to a source of 120 volts 60 Hz AC power Base Antennas Although there are only a few basic types of antennas there are many models of base Monitor antennas Some of the most popular antennas combine several frequencies Since your Receiver tunes
14. IGH raed H U CH 9 UHF FRONT SIDE Ask the manager of your Radio Shack store what the most popular and active channels are in your area He will be glad to advise you Since crystal frequencies must be extremely accurate and crystals should be matched for specific units we recommend you obtain crystals for your Receiver only from Radio Shack We can not be responsible for the poor or improper operation of from another manufacturer s CONTROL LOCATION AND FUNCTION OFF VOLUME is the power switch and Volume control When not in use rotate this control to the left to turn it off SOUELCH control is to eliminate annoying background noise between signal transmissions When properly set Squelch will keep the PRO 16A silent until a signal comes in on the channel s you are listening to then the Squelch circuit will and you hear the signal MANUAL SELECTOR Button when the SCAN MANUAL button is in the MANUAL position out use this button to advance the Receiver to the next channel in sequence Each time you press this button the Receiver will advance just one channel SCAN MANUAL Button is for determining the function of the scan ning feature In the SCAN in position each channel will be scanned automatically the MANUAL out position the PRO 16A will not scan but will remain tuned to the channel indicated by a Lighted Channel Indicator SCAN RATE Control adjust for the desired rate of
15. N RATE Use the setting that seems best for your needs It is particularly useful when using PRIORITY you can get rapid scanning plus fast scan back checking of the Priority channel SCAN DELAY The PRO 16A has a built in 2 second delay feature which virtually eliminates missed replies This circuit holds the Receiver on the channel you are monitoring for a period of 2 seconds after the carrier has gone off the air before it resumes normal scanning function This Delay circuit is switchable press DELAY in to activate the Delay function leave out to remove this delay The Priority channel has a separate built in Delay circuit which is not switchable so when PRIORITY is activated you know for sure you won t miss any replies on that channel SKIPPER CIRCUIT Your scanner has a built in skipper circuit which is fully automatic and can not be disabled It works both the SCAN and MANUAL modes of operation This feature causes the unit to skip over a locked out channel s so that there is no possibility of the Receiver stopping on a locked out channel s ACCESSORIES Your PRO 16A can be powered either from 120 volts AC or from any source of 12 volts DC negative ground Radio Shack sells a special portable power pack with 8 D cell batteries battery holder and adapter plug for a cigarette lighter socket It s a handy accessory for portable or vehicle operation For more permanent 12 volt instal lations attach the DC power ca
16. and a crystal or crystals has been installed your PRO 16A is ready to use Turn VOLUME by rotating to the right Rotate SOUELCH fully counterclockwise Set all the Channel Lock out Buttons on press in You should hear a rushing sound from the speaker Now adjust SOUELCH clockwise until you no longer hear the rushing background noise further explanation of SQUELCH adjustment is noted below If you want the PRO 16A to continuously scan the channels for which you have crystals installed you must adjust SOUELCH as instructed above then press SCAN MANUAL button in to the SCAN position The PRO 16A will constantly scan each channel in sequence when a signal appears on one of the channels the receiver will lock onto that channel and you will hear the signal If you do not want automatic scanning on one or more channels press their Channel Lock out Buttons press in to release the button so it pops out If you want to stay tuned to one channel only press SCAN MANUAL button again to make it pop out to the MANUAL position The Receiver will stop automatic scanning now pres MANUAL SELECTOR button to advance to the channel you want to listen to as indicated by the Light For MANUAL scanning the receiver can be either squelched or unsquelched for Automatic scanning SQUELCH must be set to eliminate the background noise To eliminate the annoying background noise rotate SQUELCH clockwise until the backgro
17. as noted later on under Mobile Installation With an antenna connected and a crystal installed turn the Receiver on by rotating VOLUME clockwise Rotate SQUELCH maximum counterclockwise You should hear a rushing sound in the speaker Crystals are not included with your PRO 16A because the frequencies are so numerous The frequencies used in your part of the country will be different from those used in other areas Order the crystals you want from your Radio Shack store specify the model number of this unit and the frequency you want to receive Remove the two Screws from the Crystal Compartment Cover bottom of cabinet to expose the crystal sockets and program switches Provision is made to install 16 crystals the program switch position can be used to obtain either VHF L VHF H or UHF For UHF crystals position the program switch to UHF Marked U on printed circuit board For VHF H set the program switch to VHF Marked on printed circuit board For VHF L set the program switch to VHF Marked 1 on printed circuit board In the example shown channel 1 will have a VHF H crystal and channel 9 will have a UHF crystal NOTE If you have a channel that you are particularly interested put the crystal for that channel into Channel 1 position PRIORITY Refer to OPERATION section for details on the function of PRIORITY BOTTOM OF CASE CRYSTAL COMPARTMENT CH 1 CH 1 H
18. automatic scan ning the SLOW position you ll be scanning the channels at about 10 per second FAST will give you a rate of about 20 per second Use the setting that results in a minimum of missed calls practice and experience will help you find the best setting DELAY Button when you press this button in you activate a circuit which holds the scanner on channel for about 2 seconds after the carrier has gone off the air before the scanning function once again takes over To defeat this Delay feature press again to release the button Channel Lock out Button Channel Indicator Lights PROGRAM in the position button pressed in that channel is active When you press the button again to pop it out that channel is automatically lock out and will not function The buttons light up to show which channel s is active During scan ning these lights light up in sequence when the receiver is operative on one of the channels the light for that channel wil go on When the Channel Lock out Button for that channel is out that Light will not light PRIORITY Button will l ck in channel 1 for priority reception over any other active channel Thus when pressed in if a signal comes on this channel the Receiver will automatically lock in on it and will stop scanning When the signal ceases on this channel the receiver will start scanning once again VHF Antenna Jack for VHF reception connect
19. ble to the connector on the back Then attach other end of the wires to a and source of 12 volts e g at the fuse block on a vehicle Be sure to observe correct polarity A pair of headphones can be a very useful accessory In areas where a high noise level is present in a factory at the scene of a fire or accident etc or when you want to listen privately use headphones Y our Radio Shack store has a couple of very fine selections for your PRO 16A Just plug them into the rear panel Speaker Headphone jack If you want to listen to the Receiver from a remote position or just want to use an external speaker connect it to the Speaker Headphone jack Again your Radio Shack store has some speakers specifically made for this purpose You can record off the air using a tape recorder connected to the TAPE OUT jack on the rear FREQUENCY COVERAGE For maximum sensitivity the channel frequencies you choose should be within 3 MHz of 40 MHz on the VHF band that is in the spread of 37 to 43 MHz 4 MHz of 153 MHz on the VHF band from 149 to 157 MHz For the UHF band stay within15 MHz of 480 MHz from 465 to 495 MHz The PRO 16A will function very adequately down to 30 and up 50 MHz from 148 174 from 450 to 512 MHz but with reduced sensitivity The superior reception spread of 6 8 or 30 MHz 3 4 or 15 MHz be moved up or down in this band of frequencies by special realignment of the front end circuitry
20. closely placed signals are present An important engineering achievement designed for practical appli cations the PRO 16A is remarkably easy to use yet its up to date complex circuit consists of 52 separate transistors three of which are Field Effect Transistors six intergrated circuits which incorpo rate the equivalent of hundreds of components 66 diodes and 1 zener diode This Receiver is designed to operate from either 120 volts AC or 12 volts DC Negative Ground If it fails to operate and there is no clear reason for the failure first check the power switch part of Volume control Also before connecting the PRO 16A receiver to a DC power supply check the voltage polarity Attempting to operate the negative ground PRO 16A from one of the rare positive ground automotive or boat electrical systems or from a wrongly connected battery will at least blow a fuse It may do further damage so that expensive and time consuming repairs are necessary before the PRO 16A can be used again The Radio Shack warranty does not apply to any damage caused by this inadequate lightning protec tion or other improper connections WARNING TO PREVENT FIRE OR SHOCK HAZARD DO NOT EXPOSE THIS RECEIVER TO RAIN OR MOISTURE SPECIFICATIONS SEMICONDUCTOR COMPLEMENT 52 transistors 6 integrated circuits and 67 diodes 30 50 MHz 148 174 MHz and 450 512 MHz Sixteen as determined by any one of 16 crystals operating in the
21. in both high and low au VHF we suggest an antenna such as our Hi Low VHF Ground Plane 20 015 Or you could use our Hi VHF UHF Ground Plane 20 176 For UHF we recommend 20 182 our UHF Ground plane antenna Y MOBILE INSTALLATION Safety and operating convenience are the primary factors to consider when you install any equipment in a vehicle Be sure you can easily reach the Receiver s controls Also be sure the connecting cables do not interfere with the operation of the vechile brake accelerator etc You can mount the Receiver to the underside of the dash or instru ment panel in the vehicle or boat Use the universal mounting bracket provided Take care when drilling holes that you do not drill into existing wires or trim The PRO 16A is designed to operate from a negative ground 12 volt DC source Be sure you connect power leads with the correct polarity Use the DC Power cable provided The other end of these wires can be connected to an Auto Cigarette Lighter Plug Catalog Number 274 331 or you can make the connections directly to the fuse block of the vehicle or boat Be sure to observe correct voltage polarity to and to IMPORTANT If your car has been burning out headlamps and other bulbs at a rapid rate have the voltage regulator checked for proper output excessive voltage more than 16 volts can cause serious damage to your receiver MOUNTING BRACKET SCREW Mobile Antennas
22. u the channel frequencies used by local radio services A volunteer police or fire employee can also be a good source of this information An interesting service is the Mobile Telephone FCC has assigned this service channels in the range of 152 51 to 152 81 MHz at every 0 030 MHz channels are 30 kHz apart Also 454 375 to 454 95 MHz with channels 25 kHz apart from 454 375 to 454 625 and then every 50 kHz up to 454 95 As a general rule on VHF most activity will be concentrated between 153 785 and 155 98 and then again from 158 73 to 159 46 MHz Here you ll find local government police fire and most such emergency services If you are near a railroad yard or major railroad tracks look around 160 0 to 161 9 for them In some of the larger cities there has been a move to the UHF bands for these emergency services Here most of the activity is in a spread of 453 05 453 95 and again at 456 025 459 95 MHz In the UHF band the overall spread of 456 025 459 95 and again at 465 025 469 975 MHz is used by mobile units and control stations associated with base and repeater units which operate 5 MHz lower that is 451 05 454 95 and 460 025 464 975 MHz This means that if you find an active channel inside one of these spreads you can look 5 MHz lower or higher as the case may be to find the major base station repeater for that radio service NATIONAL WEATHER SERVICE RECEPTION Continuous weather broadcasts are transmitted 24
23. und noise just stops You can t adjust SQUELCH properly while listening to a station so wait till signals cease If you set SOUELCH as noted above the PRO 16A will appear dead until a signal comes in when a signal comes in the Squelch circuit opens up and you hear the signal When the signal ceases the Squelch circuit closes and cuts out all sound until the next signal comes in PRIORITY In most areas there is usually one channel you will want to monitor consistently The Priority function allows you to do this and yet you can still scan all the other channels When the PRIORITY Button is pressed in the scanner will operate as usual scanning across channels 1 thru 16 looking for an active channel However if it should stop on any channel other than the priority channel for more than two seconds the Receiver will automatically scan back and check the priority channel This priority channel sampling occurs almost instantaneously and if the priority channel is not active the scanner returns to the channel being monitored previously This scan back takes only six hundredths of a second so there is scarcely any interruption to the signal you were monitoring If the priority channel is active the scanner will continue to monitor it until it clears and then return to the channel previously being monitored SCAN RATE Scan Speed You can vary the scanning rate from about 10 to 20 channels per second by adjusting SCA
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