Scanner Frequently Asked Questions
Section 2 - General Information and Accessories


GENERAL SCANNER INFORMATION

Programming

Terminology

Troubleshooting

Usage


SCANNER ANTENNAS AND ACCESSORIES


GENERAL SCANNER INFORMATION

Product: Programming
Question: Do you have scanner frequency lists available?
Answer: The only source we have for scanner frequencies is the "Police Call" directory for your area, which should be available through your local RadioShack store and can also be ordered on-line or by calling 800-843-7422. The catalog numbers for the "Police Call" books are as follows:
620-2518 - CT, ME, MA, NH, NY, RI, VT
620-2519 - DE, MD, NJ, PA
620-2520 - IL, IN, KY, MI, OH, WI
620-2521 - IA, KS, MN, MO, NE, ND, SD, AZ, CO, ID, MT, NM, NV, WY, UT
620-2522 - DC, FL, GA, NC, SC, VA, WV, PR
620-2523 - AL, AR, LA, MS, OK, TN, TX
620-2524 - CA, OR, WA

The Police Call Directories are also available as a single Compact Disc (Cat. No. 620-2502).

These can be purchased on-line by clicking on the number link to go to the catalog page.

 
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Product: Programming
Question: How do I enter a 7-digit frequency when the scanner only takes 6 digits?
Answer: You will need to round off the last digit.
 
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Product: Terminology
Question: What is meant by the "step-rate" of a scanner?
Answer: This is the function of the step rate of the scanner:

856.2675 less the beginning frequency of the band, which, in this case, is 851.0000 MHz equals 5.2675 divided by the step rate, which is 0.0125 (12.5 kHz) equals 421.4. Since this number is not an even full number, the scanner will drop back. To find out how much - multiply the full number portion (421) times 0.0125 which equals 5.2625 plus the beginning frequency in the band, 851.0000 equals 856.2625. Use either that number or that number plus 0.0125 which equals 856.2750.

Usually, one of the two calculated values will be close enough to pick up the desired channel.

 
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Product: Terminology
Question: How do I tell if my scanner uses dual or triple conversion?
Answer: Look at the number of IF Frequencies. Dual-conversion scanners have only 2 IF frequencies; triple-conversion scanners have 3 IF frequencies.
 
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Product: Terminology
Question: What does "SMR" mean in call book lists?
Answer: "SMR" indicates a Service Maintenance Repeater. Radio operators must be a member of that club to transmit to that repeater.
 
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Product: Troubleshooting
Question: My scanner hangs up on a particular frequency; however, the problem goes away when I remove the antenna.
Answer: If you remove the antenna and it goes away, this indicates that the problem is either a signal in the air OR a strong nearby signal is mixing with something else and forming an IMD (Intermodulation) product at that/those frequencies. To fix this, you will need to either:
  • Use the lockout key to program that/those frequencies as "search skip". When the scanner stops on the undesired frequency during a search, hit the lockout button to store the undesired frequency, and the scanner will automatically skip over it after that.
  • Use an external antenna with either high shielding OR an external antenna with an attenuator (such as the 6 dB Attenuator 150-1257) and the appropriate adapters.
 
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Product: Troubleshooting
Question: Why does my RadioShack scanner pick up the same transmission up on a different frequency from the frequency I receive on a super-heterodyne or dual-conversion scanner?
Answer: The frequencies that you're picking up on your original scanner are images or harmonics of the frequency that you are actually listening to. This is a common result when changing from a scanner that utilizes simple super-heterodyne versus a scanner with triple conversion. The actual frequency that your original scanner is picking up is a second or third harmonic away from the actual frequency being transmitted. The RadioShack scanner should be picking up the correct frequency.

For example, 145.000 MHz has the following harmonics:

F (tx) = 145.000 MHz
F (image) = 144.545 MHz and 145.455 MHz (1st order harmonics).
F (image) = 144.090 MHz and 145.910 MHz (2nd order harmonics).
F (rx super-heterodyne) ~ 144.090, 144.545, 145.455, or 145.910MHz
F (rx triple-conversion) ~ 145.000 MHz

This is an example of triple conversion versus simple super-heterodyne, or dual conversion methods of receiving. The frequency received will be truer to the actual frequency transmitted on a scanner/receiver with triple conversion than on one with dual conversion and much the same when comparing dual conversion to simple super-heterodyne. The methods of using double or triple conversion aid in eliminating unwanted images (ghost frequencies) and other types of noise present in the different band of frequencies.

 
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Product: Troubleshooting
Question: I need a service manual, and the local store said there isn't one for my scanner. Why?
Answer: Early in 1997, representatives from the scanner industry, including RadioShack, met informally with the FCC to discuss current problems in the scanning hobby. Identified as a major problem was the ability of some scanner hobbyists to develop illegal modifications that allow scanners to receive cellular telephone transmissions. Among the possibilities discussed for eliminating this problem were the total epoxying of all circuit boards, which would render scanners both unmodifiable and unserviceable, or the restriction of technical information regarding scanner circuit design.

As a result of this meeting, RadioShack limited the availability of scanner service manuals to RadioShack Service Centers only.

While RadioShack understands the desire of the do-it-yourself community to have easy access to service information, we feel the interests of the scanning hobby as a whole are best served by making it more difficult to develop illegal modifications by restricting access to some service manuals containing schematics. Therefore, in response to industry concerns, RadioShack is implementing the following policy in regards to the release of service information and the servicing of scanners.

RadioShack will withhold schematics (service manuals) for all scanners that can receive 800 MHz or above which were submitted for FCC certification after April, 1997. As of December 12, 1997, this means that service manuals for the following RadioShack scanners will not be available: 20-417 (PRO-2048), 20-430 (PRO-2050), 20-512 (PRO-67), and 20-520 (PRO-90), along with all future service manuals within the stated criteria.

To the extent that service manuals exist and are in stock, schematics (service manuals) for scanners that can receive 800 MHz or above that were submitted for FCC certification before May, 1997 will continue to be available to customers and others.

To the extent that service manuals exist and are in stock, schematics (service manuals) for scanners that cannot receive 800 MHz or above will continue to be available to customers and others.

Modified scanners (regardless of frequency or date of manufacture) will not be serviced by RadioShack. These scanners will be returned to the customer with a notice indicating that the unit appears to have been modified and if the scanner is returned to its original specifications, RadioShack will use reasonable efforts to repair it.

To the extent that scanner parts are available and in stock, scanner replacement parts will continue to be available regardless of the scanner's frequency range or date of manufacture.

 
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Product: Troubleshooting
Question: Why do I get constant noise on a particular channel?
Answer: It may be a birdie channel. Birdies are frequencies your scanner uses when it operates. The most common birdies to watch for are listed below.

 

31.05 MHz 124.20 MHz
41.40 MHz 134.55 MHz
51.75 MHz 144.90 MHz
113.85 MHz 155.25 MHz
 
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Product: Troubleshooting
Question: When I plug a speaker into the earphone jack, the audio volume cuts down a lot & I have to turn the volume up - is this normal?
Answer: To connect to an earphone jack requires an amplified extension speaker; if your speaker is not amplified, you get significantly lower volume as you describe.
 
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Product: Troubleshooting
Question: My scanner will accept 821.2620 but then rounds it off to 821.250 (for example)? Why can't I enter the correct frequency?
Answer: The scanner frequencies must correspond to the preprogrammed step rate; this is normal operation.
 
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Product: Troubleshooting
Question: I tried charging NiMH batteries in my scanner & the batteries appear to be getting very hot/expanding/etc.
Answer: NiMH batteries require a different charging circuit from NiCd. You should never charge NiMH batteries in any device or charger unless it clearly specifies that it will charge NiMH batteries.
 
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Product: Troubleshooting
Question: I put new batteries in my scanner but it shuts off after a few seconds.
Answer: Clean the battery contacts using a rubber eraser. If the problem continues, try different batteries. If the problem still continues, you would need to have the radio serviced.
 
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Product: Troubleshooting
Question: My scanner stops on a particular channel or frequency when using the DC adapter and the engine is running; it works fine when the engine is not running.
Answer: Something in the engine is generating RF interference. You would need to determine where this is coming from and install a filter. The best place to start is with a noise filter on the DC line, such as:
270-030 Basic Noise Eliminator
270-051 10-amp Noise Filter
270-055 20-amp Heavy-duty Noise Filter
 
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Product: Usage
Question: What scanner antenna should I use?
Answer: The antenna which will be best for you will depend on what type of scanner you have and the signal strengths. The table below lists our range of antennas available.

Antenna Details

 

Cat. No. Type of Scanner Frequency Range Connector on Antenna
200-0043 Outdoor 25-1300 MHz (Receive)
50, 144, 200, 440, 900 & 1296 Ham (Transmit)
SO-259 connector
200-0176 Outdoor 108-1300 MHz SO-259 connector
200-0161 Desktop 30-512 MHz Motorola connector
200-0032 Mobile (Magnet-mount) 25-1300 MHz BNC connector
200-0011 Mobile (Glass-mount) 25-1300 MHz BNC connector
200-0006 Handheld 25-1300 MHz BNC connector
200-0034 Handheld 27-50, 138-174, 406-512, 806-940 MHz (Receive)
144-148 (2M), 438-450 MHz (70 cm) (Transmit)
BNC connector


Adapters Required

 

Connector on Antenna Scanner Requires Adapter
Motorola BNC 278-117 Adapter
BNC Motorola 278-160 Adapter
SO-259 PL-259 278-192 SO-259 Coupler
SO-259 BNC PL-259 to PL-259 Cable
PL-259 to BNC Adapter


PL-259 Cables

 

Length Cable Type Cat. No.
2 feet RG-58 278-968
5 feet RG-8 278-969
10 feet RG-8M 278-979
20 feet RG-58 278-967
50 feet RG-58 278-971
50 feet RG-8 278-980
 
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Product: Usage
Question: How can I record my scanner's broadcasts?
Answer: You would need to connect the headphone output jack to a tape player using the 274-889 1/8" Mono Plug to Two RCA Jacks Adapter and RCA A/V Patch Cables.

Good (two nickel-plated RCA Plugs on each end)

420-2351 3-foot Cable
420-2352 6-foot Cable
420-2356 12-foot Cable

 

Better (RCA Plugs with gold-plated contacts, two straight on one end, two right-angle on the other)

420-2650 18-inch Cable
420-2651 3-foot Cable
420-2652 6-foot Cable
420-2654 12-foot Cable
420-2653 20-foot Cable
420-2655 36-foot Cable

 

Best (Gold-plated RCA Plugs on each end)

420-2601 3-foot Cable
420-2605 6-foot Cable
420-2606 12-foot Cable
420-2614 20-foot Cable
 
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Product: Usage
Question: I am going out of the country; will my scanner work and do you have frequency lists for (country)?
Answer: RadioShack products sold in the US are not intended for use and may not function properly outside of the US due to power and other issues.

Additionally, your radio scanner may be illegal to use in your destination. We cannot recommend using a US scanner outside of the United States and strongly suggest that you contact a reliable source of information (travel agency, government body) to determine the legality of this use. We do not have a source for frequency lists outside the United States.

 
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Product: Usage
Question: Do you sell a scanner to pick up cellular or cordless telephone frequencies?
Answer: No! It is illegal to use a scanner for this purpose, and RadioShack scanners are designed to be unable to do this. The legal issues are covered under the Electronics Communications Privacy Act of 1996 as amended under Section 2511. This information can be found at the local public library under US Code 2511.
 
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Product: Usage
Question: How do I use stereo headphones with my scanner?
Answer: You need a mono to stereo adapter such as 274-368 (nickel-plated) or 274-882 (gold-plated to minimize signal loss).
 
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Product: Usage
Question: Can I use an external CB antenna with my scanner?
Answer: CB antennas are optimized for the low end of the spectrum; CB frequencies are 26-28 MHz. While it may work, your reception in the higher frequencies would not be equivalent to what you would get with a scanner antenna.
 
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Product: Usage
Question: What kind of cable should I use to connect an outside antenna to my scanner?
Answer: You need to use 50-Ohm cable, such as either RG-58, RG-59, RG-8 or RG-8M. For cable lengths greater than 80', you should use RG-8 to counteract signal loss. We sell the following cables:
        Loss in dB per 100'    
Cat. No. RG Type OD Velocity
Factor
@ 100 MHz @ 400 MHz Capacitance
per Foot
Center
Conductor
278-1314 RG-58 .196" 66% 4.5 10.0 28.5 pF 20-gauge (solid)
278-1313 RG-8M .242" 78% 3.7 8.0 25.2 pF 16-gauge (19x29)
278-1312 RG-8 .408 66% 1.9 4.1 26.4 13-gauge (7x21)
 
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Product: Usage
Question: What is the range in miles?
Answer: Range for a scanner cannot be specified, as it depends on the level of interference and the transmitter strength, which can vary widely.
 
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SCANNER ANTENNAS AND ACCESSORIES

Product: Extension Speaker Cat. No.: 200-0009
Question: Do you carry a speaker adapter from 1/8" to 3/32"?
Answer: Yes, it is available as Cat. No. 274-0327.
 
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Product: Scanner On-Glass Antenna Kit Cat. No.: 200-0011
Question: Will this work on tinted windows?
Answer: No.
 
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Product: Scanner On-Glass Antenna Kit Cat. No.: 200-0011
Question: Can I use this to transmit?
Answer: No.
 
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Product: Base Scanner Antenna Cat. No.: 200-0013
Question: Is there a replacement?
Answer: Yes, it is available as Cat. No. 200-0043.
 
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Product: Rubber Duckie Antenna Cat. No.: 200-0034
Question: What is the frequency coverage and length?
Answer: The frequencies are given below:

Receive Only

27 - 50 MHz, Lo VHF
138 - 174 MHz, Hi VHF
406 - 512 MHz, UHF and "T" band
806 - 940 MHz, 800 MHz Band

Receive/Transmit

144 - 148 MHz, 2M Band
438 - 450 MHz, 70 cm Band

Length: 240 mm

 
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Product: Scanner Antenna (30 MHz to 1300 MHz) Cat. No.: 200-0042
Question: What connector do I use to connect this to a scanner?
Answer: The connector for this antenna is an F jack. There are two methods for connecting it to a scanner:
  • You can use an RG-6 cable with an F plug on each end and then use the F to BNC adapter (Cat. No. 278-0251) between the cable and the scanner.
  • You can use an RG-6 cable with an F plug on one end and a BNC plug on the other. We do not sell this cable pre-built.

To construct the cable in the second option, you would need the following:

 
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Product: Scanner Antenna (30 MHz to 1300 MHz) Cat. No.: 200-0042
Question: What is this made of?
Answer: The antenna is made out of aluminum.
 
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Product: Discone Scanner / Ham Base Station Antenna Cat. No.: 200-0043
Question: Is this directional?
Answer: No, it is omnidirectional.
 
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Product: Discone Scanner / Ham Base Station Antenna Cat. No.: 200-0043
Question: What is the length and diameter of the lower 8 rods?
Answer: The diameter is 0.190"; the length is 31.875".
 
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Product: Discone Scanner / Ham Base Station Antenna Cat. No.: 200-0043
Question: What are the frequencies of the bottom radials?
Answer: What is being referred to as "radials" are the radiating (or center) elements. In a discone antenna, the horizontal elements are connected to the shield and the cone is connected to the coax center conductor. The actual configuration is an upside down half-bow-tie. It is the width of the cone ( vs. the cone's length ) that gives this antenna its broad band performance (the discone is 30 - 1300 MHz; the vertical whip is resonant in the 10M ham and 11M CB bands, for total 25 - 1300 MHz performance).
 
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Product: UHF/VHF Base Antenna Cat. No.: 200-0176
Question: How is it mounted and does it come with cable?
Answer: You can use other mast mounts to mount this; it uses U bolts. It does not include cable.
 
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Product: 9-Volt Scanner Adapter Cat. No.: 200-0188
Question: What replaces this adapter?
Answer: This was a 9V, 300 mA (minimum) adapter with a 1.3 mm / 3.4 mm plug. The 273-1810 DC/DC adapter meets these requirements and includes the correct plug. The 273-1767 AC/DC adapter meets these requirements and comes with your choice of one free adaptaplug. You will need the "H" size adaptaplug, Cat. No. 273-1711.
 
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Product: Headphones with Earpad Cat. No.: 200-0282
Question: How much noise do these block out?
Answer: These use passive noise reduction and are not rated in dB.
 
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Product: Headphones with Earpad Cat. No.: 200-0282
Question: What is the sensitivity (dB rating)?
Answer: Sensitivity = 100dB +/- 5dB @ 1khz
 
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Product: Koss Speedzone Headset Cat. No.: 200-0284
Question: How much noise do these block out and what is it designed for?
Answer: These use passive noise reduction and are not rated in dB. They are ideal for hand-held race scanners.
 
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Product: Koss Speedzone Headset Cat. No.: 200-0284
Question: What are the specifications on these headphones?
Answer: The headphones are rated at:
Impedance: 60 ohms
Frequency Range: 40 Hz - 20 kHz
Sensitivity: 102 1 M / 1 mW
 
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