CB and FRS Radios FAQ

1) 26.965 MHz	9) 27.065 MHz	17) 27.165 MHz	25) 27.245 MHz	33) 27.335 MHz
2) 26.975 MHz	10) 27.075 MHz	18) 27.175 MHz	26) 27.265 MHz	34) 27.345 MHz
3) 26.985 MHz	11) 27.085 MHz	19) 27.185 MHz	27) 27.275 MHz	35) 27.355 MHz
4) 27.005 MHz	12) 27.105 MHz	20) 27.205 MHz	28) 27.285 MHz	36) 27.365 MHz
5) 27.015 MHz	13) 27.115 MHz	21) 27.215 MHz	29) 27.295 MHz	37) 27.375 MHz
6) 27.025 MHz	14) 27.125 MHz	22) 27.225 MHz	30) 27.305 MHz	38) 27.385 MHz
7) 27.035 MHz	15) 27.135 MHz	23) 27.255 MHz	31) 27.315 MHz	39) 27.395 MHz
8) 27.055 MHz	16) 27.155 MHz	24) 27.235 MHz	32) 27.325 MHz	40) 27.405 MHz

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Product: CB Radios

Question: What is the range of my CB?

Answer: A CB radio with the maximum legal power will have a range of up to 4 miles. However, due to interference and/or obstacles, it is not possible to determine exact range for a certain area; range will vary regardless of the type, model or manufacturer of radio used.

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Product: CB Radios

Question: I get noise on my radio when I connect it in my vehicle; how do I troubleshoot it?

Answer: The first thing to check is if the noise is still present if you disconnect the antenna from the CB radio.

If the noise goes away, then there may be a component that needs to be shielded, or the antenna cable needs to be moved to a location where the interference is minimized. As well, a ground strap may need to be installed that connects the hood to the firewall.

If the noise doesn't minimize, then the problem may be caused by noise through the power or ground connection. A suggestion is to ground to the engine block and use the positive battery terminal as the power source for the CB radio.

Additional filtering may also be necessary. We offer several automotive noise filters under Audio, Automotive Electronics, 12 Volt.

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Product: CB Radios

Question: What are the "10-codes"?

Answer: The basic 10 codes are listed in all of our Citizen Band Radios manuals; they are as follows:

Code	Meaning	Code	Meaning
10-1	Cannot understand your message.	10-16	10-16 Reply to message.
10-2	Your signal is good.	10-17	10-17 En route.
10-3	Stop transmitting.	10-18	10-18 Urgent.
10-4	Message received and understood.	10-19	10-19 Contact __________
10-5	Relay information to ___________.	10-20	10-20 What is your location?
10-6	I am busy or are you busy?	10-21	10-21 Call __________ by telephone.
10-7	Out of service.	10-22	10-22 Cancel last message.
10-8	In service.	10-23	10-23 Arrived at the scene.
10-9	Repeat last message.	10-24	10-24 Assignment complete.
10-10	Negative (No).	10-25	10-25 Meet __________
10-11	__________ in service.	10-26	10-26 Estimated time of arrival is __________
10-12	Stand by.	10-30	10-30 Use caution.
10-13	Report __________ conditions.	10-31	10-31 Pick up.
10-14	Information.	10-33	10-33 Emergency traffic. Clear the channel.
10-15	Message delivered.	10-34	10-34 What time is it?

You can get further information on specialized codes used by local emergency agencies, through the Police Call Handbook for your area, by contacting your local Ham or Scanner club or by contacting the agency directly.

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CB Radios: Product-specific Questions

Product: TRC-239 40-Channel 5-Watt CB Walkie-Talkie	Cat. No.: 210-1628
Question: Is this a 5-watt or 4-watt radio? It is shown as 5-watt on the box, but it is listed as 4-watt in the manual.
Answer: There are two methods of measuring CB output, which were developed/adopted by the FCC. The old method measured signal strength into the final output circuit of the radio, and the maximum allowable was 5 watts. The new method measures output coming off the antenna. Because the radio consumes approximately one watt when operating, the maximum allowable at the antenna is 4 watts. This radio was designed to provide the maximum allowable power. The number on the box refers to the old method, and the specifications list showing 4 watts is based on the newer method.

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Product: TRC-207 40-Channel Walkie-Talkie	Cat. No.: 210-1645
Question: What power supply do I need to use this with AC power?
Answer: This requires an AC to DC power supply which provides 12VDC and at least 2.5 Amps. RadioShack sells a number of DC Power Supplies.

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Product: TRC-504 40-Channel Mobile CB Radio	Cat. No.: 210-1704
Question: How many watts does this unit put out through the PA jack and at what impedance?
Answer: The output is 4 watts at 8 ohms.
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CB Accessories: General Questions

Product: CB Antennas

Question: What is the gain for a particular CB antenna? What antenna has the best gain?

Answer: Gain can be measured either against a 1/4-wave antenna or 1/2-wave. For most antennas, the old industry standard was to compare antenna gain to an isotropic antenna, which is a theoretical antenna that has the gain of a 1/2-wave antenna, but all emissions emanate from a pinpoint (that's why it's only theoretical). An isotropic antenna can be loosely defined as a single half-wave element. CB radio frequencies center around 27.2 MHz. By today's standards, that's a low frequency, even though back when it was named, it was called the "HF" or High Frequency band. The lower the frequency, the LONGER the wavelength. The longer the wavelength, the longer the antenna needs to be to have any gain. There is a commonly used formula to calculate the starting wire length for a 1/2 wavelength wire antenna:

Length = 468/Freq

Length is in feet, and Freq is in MHz. For CB, we solve this as follows: length = 468/27.2 = 17 feet, 2-1/2 inches. So, we now know that an antenna of about 17 feet will have the same gain (zero gain) when compared to a 1/2-wavelength antenna.

Over the years, antenna manufacturers played a specification game with each one trying to show their antennas were better, and eventually someone started comparing to a 1/4-wave whip instead of the isotropic. Since a 1/4-wave has only half the gain of an isotropic antenna, they were able to advertise twice the gain. However, the antennas themselves didn't get better - only the advertised gain number changed. It's important when you see a gain specification to find out what the standard reference antenna was.

In CB, the standard reference antenna is a 102" whip. Since all mobile antennas (except the 102" whip, of course) are shorter than 1/4-wave, performance will NOT be as good as the 102" whip. So, no one in the industry has ever published gain specs for mobile CB antennas - since they would ALL look bad!

Even heavily advertised branded antennas compare their antennas to other comparable antennas. You may notice that they are not compared to a 102" whip, and it's easy to understand why. These expensive antennas are not as good as the simple, inexpensive 102" quarter-wave whip antennas.

We suggest that you purchase the largest CB antenna that is practical for your vehicle. You should consider whether your vehicle needs to get in and out of a garage, and where the antenna will mount in order to make a good decision. All claims aside, in mobile CB antennas, there's just no compromise for length!

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Product: CB Antennas

Question: What is the impedance for a particular CB antenna?

Answer: All our CB antennas have roughly 50 Ohm impedance to match the output of the CB radio. The impedance is not critical as 25 Ohms to 100 Ohms is acceptable. Best signal transfer occurs at 50 Ohms, so every design is optimized very close to 50 Ohms.

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Product: CB Antennas

Question: Why do I get continuity between the whip portion and the center, and between the whip and shield portion, but not between the center and the shield? This was brought up by a customer who purchased a CB/Ham antenna and decided to run a continuity test between the center and the ferrule or the outer part of the coax which is attached to the shield. There was no continuity, but between the whip portion and the center there was continuity and there was continuity also between the whip and shield portion. Given this information, will the antenna radiate the signal properly and not burn out the transceiver? How can an antenna work properly if the center and shield are shorting out the signal?

Answer: Typically the capacitance of the cable will increase the resistance between the center conductor and shield of the cable, and the antenna will generally have a coupling capacitor prior to the connection to the cable. But between the whip portion and the center, there was continuity and there was continuity also between the whip and shield portion. The DC resistance of any antenna is not the same as the total impedance of that antenna. All DMM's measure only the DC resistance and not the total impedance of any item.

For example, measure the resistance of any "8 Ohm" antenna with a DMM. The resulting measurement will vary, generally as between 3-6 Ohm. This is only showing the "DC" component of the total impedance.

The antenna will radiate the signal properly and not burnout the transceiver as long as the SWR (Standing Wave Ratio) remains between 1.0 and 2.5. The antenna can work as long as the impedance at the desired frequency remains 50 Ohms and the SWR remains between 1.0 and 2.5. Once again, the measurement is only accurate for DC (0 Hz). Antennas are tuned for operation within certain band limits. The impedance can only be tested at that frequency or band of frequencies.

There are other components in the manufacture of an antenna. Internally, the antenna will have a combination of components to help tune the antenna to the proper wavelength and power rating. Some antennas utilize inductors and capacitors, others use resistors and capacitors, still others may combine one or all of these in the design of the antenna. These "tuning circuits" can be a combination of LC, LR, RC, or even LRC (L = inductor, R = resistor, C = capacitor). The most common is an inductor or coil, sometimes referred to as a "loading" or "base" coil. The resistance of almost any coil will measure less than 10 Ohms at DC or 0 Hz.

These concepts can be studied further via reference books such as the ARRL handbook and/or ARRL Antenna book.

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CB Accessories: Product-specific Questions

Product: CB / Ham / Commercial Radio, 10-meter Base Station Antenna	Cat. No.: 210-0969
Question: What is the wave length of this antenna?
Answer: This antenna is a 1/2 wave antenna.

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Product: CB/Ham Mobile Antenna	Cat. No.: 210-0972
Question: What are the dimensions for this antenna?
Answer: The approximate measurements for this antenna are as follows: Whip 39" Coil 3.5" Base 4.0" Grand total 46.5"

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Product: Fiberglass Magnetic Mount CB Antenna	Cat. No.: 210-0989
Question: What is the wave length of this antenna?
Answer: The antenna is a 5/8 wave. 5/8 wave is more efficient than 1/2 wave, providing a better impedance match without an antenna tuner (which we do not carry for CB antennas). Most mobile antennas we carry (for CB, ham, business band, etc.) will be either 1/4 wave or 5/8 wave, unless specifically noted as 1/2 wave. Some whips may be either 1/4, 1/2, 5/8 or full wave. Anything with a coil should be a 5/8 wave.

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Product: Magnetic Mount CB Antenna	Cat. No.: 210-0994
Question: Why isn't the cable the same length as listed in the catalog? How do I reduce the noise level of my radio using this antenna?
Answer: The antenna cable length can vary; 9.5" is the minimum length supplied. Each antenna is tuned for the length of cable attached to the antenna; you must not cut the cable or change the cable length. Doing so will void the warranty on this antenna. For best performance, the antenna should be tuned for proper SWR. You can tune this antenna as follows: Insert the top whip element halfway into the coil and tighten the screw at the top of the coil. Measure SWR at Channel 1 and Channel 40. Ideally, the SWR should be the same at both. If Channel 1 has a higher SWR, loosen the screw and lengthen the whip. If Channel 40 has a higher SWR, loosen the screw and shorten the whip. When the SWR at both is as close as you can get it, tighten the screw fully.

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Product: Magnetic Mount CB Antenna	Cat. No.: 210-0994
Question: What should this antenna's SWR reading be?
Answer: Ideally, SWR should be 1:1; however, at a minimum, it should be less than 3.

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Product: Noise-Canceling Pre-amplified Dynamic Microphone	Cat. No.: 210-1177
Question: Will this work with my radio?
Answer: This microphone's pinouts are not standard and don't match some radios. Pinout information for this microphone are available on-line under Plug Wiring on the On-line Manual.

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Product: Noise-Canceling Pre-amplified Dynamic Microphone	Cat. No.: 210-1177
Question: I put the 210-1177 on my radio, and now the channels on the radio start changing on their own, and don't stop.
Answer: This occurs if the radio is the type that has channel up/down buttons on the original microphone. This microphone cannot be used with that type of radio.

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FRS Radios and Accessories: General Questions

Product: FRS Radios

Question: What are the FRS frequencies?

Answer: The FRS channels are on the following frequencies:

1. 462.5625 MHz	8. 467.5625 MHz
2. 462.5875 MHz	9. 467.5875 MHz
3. 462.6125 MHz	10. 467.6125 MHz
4. 462.6375 MHz	11. 467.6375 MHz
5. 462.6625 MHz	12. 467.6625 MHz
6. 462.6875 MHz	13. 467.6875 MHz
7. 462.7125 MHz	14. 467.7125 MHz

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Product: FRS Radios

Question: Can you explain what "Tone Burst" and "Quiet Code" mean? Is it a type of CTCSS?

Answer: "Quiet Code" allows you to set a sub-tone and filter on your radio, so that you will only hear transmissions which are using the same sub-tone as your radio. By using a Quiet Code, all cross-talk interference is eliminated (unless, of course, someone else is on the exact same channel and Quiet Code).

"Tone Burst" is a unique scheme used by the 210-1809 to accomplish the "Quiet code" function. It is not CTCSS and is not compatible with the standard 38 tone CTCSS Quiet Codes. Out-of-the-box, the 210-1809 FRS radio is an open carrier (no tone burst required) -- both switches are set in the Down position. Setting either (or both) switch(es) to the Up position activates Tone Burst on TX and requires the same Tone Burst setting on RX. This allows the 210-1809 to provide a very low cost version of "Quiet Code." Even though only 3 settings are possible, because it is not compatible with CTCSS Quiet Codes, all cross-talk interference is eliminated unless someone else is using a pair of 210-1809's locally on the exact same channel and Quiet Code.

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FRS Radios and Accessories: Product-specific Questions

Product: 2-Way Family Radio Personal FM/UHF FRS	Cat. No.: 210-1807
Question: How long will the batteries last with no TX or RX?
Answer: The batteries should last approximately 30 hours on standby.

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Product: 2-Way Family Radio Personal FM/UHF FRS	Cat. No.: 210-1807
Question: Is the 190-0314 headset compatible with this? If not, what headset should I use?
Answer: The 190-0314 headset is not compatible; we recommend the 190-0312 headset for this item.

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Product: FRS Radio	Cat. No.: 210-1810
Question: What are the requirements for batteries and charger?
Answer: The batteries and charger are available as follows: 3.6V 1200 mAh NiMH Battery (Cat. No. 960-2081) Desktop charger, AC/DC adapter (Cat. No. 21-1830) The AC Adapter supplied with the 120-1810 has the following ratings: Input: 120 V, 60 Hz, 14.4 W Output: 9 VDC, 1A, Center Negative Because these items are only available by special order, you will need to contact either your local RadioShack store or RadioShack.com at 800-241-8742 to place an order.

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Product: FRS Radio	Cat. No.: 210-1810
Question: What accessories are available?
Answer: The following product accessories are available either through RSU Fulfillment Center or store stock. 210-0589 Camouflage Cloth Case The following items are available by special order only: P27-1810B Leather Case T210-1810AC AC adapter...use store stock T210-1810BTY NiMH 3.6 Volt/ 1200 mAh battery T210-1810LC Black Leather Case Because these items are only available by special order, you will need to contact either your local RadioShack store or RadioShack.com at 800-241-8742 to place an order.

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Product: FRS Radio	Cat. No.: 210-1810
Question: How do I change the function?
Answer: In order to change a particular function, the function (Channel, Quiet, & Volume) has to be flashing. Then, turn the rotator knob to the desired setting.

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Product: Two-Way Personal Radio	Cat. No.: 210-1811
Question: The radio keeps flashing between Channel and UL; how do I get UL off the display?
Answer: UL means the PLL (Phase Lock Loop) has come unlocked. You will need to take the radio to your local RadioShack store and have it serviced.

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Product: Two-Way Personal Radio	Cat. No.: 210-1813
Question: Is the 210-1813 Radio the replacement for or the same as the 210-1810 Radio? Both have the same features and power rating and also look the same in pictures.
Answer: The 210-1813 is a direct replacement for the 210-1810. Since there were a couple of feature changes, we changed the model number. The feature changes are: No adjustable volume on call signal (it was separately adjustable by the receiving station in the 210-1810) Hi/Lo power output (saves battery life when communication is possible in low power setting)

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Product: FRS Radio	Cat. No.: 210-1822
Question: Why does my display lock up and how do I fix it?
Answer: If a radio is operated on a near dead batteries and the channel or the user repeatedly changes quiet code, the microchip can eventually get a checksum error from the memory. Once reset, the memory is cleared and the problem does not occur again. To reset a 210-1822, press and hold the monitor button while you turn on the radio.

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