More Information on the MURS Radio system

Here is another post by C.E, Harris on the MURS radio.
The FCC created the Multi-Use-Radio Service or MURS by refarming the five Business Pool VHF frequencies formerly known as the VHF “color dot” frequencies from Part 90 to Part 95 of the FCC Regulations to become a new Citizens Band Radio Service for private, two-way, short-distance voice or data communications service for personal or business activities of the general public.

No license is needed. You may operate a MURS transmitter if not a representative of a foreign government; and you use the transmitter in accordance with the rules. No illegal activity, no profanity, be an adult and play nice. The five channels authorized are available on a shared basis only and may not assigned for exclusive use of any entity. Users must cooperate in the selection and use of channels in order to reduce interference and avoid interference to other transmissions. Around cities you will hear fast food drive-in windows, warehouse operations, landscapers and trash collection, building maintenance and construction site crews. MURS operation is authorized anywhere a CB station is authorized, except aboard aircraft in flight.

MURS users shall take reasonable precautions to avoid causing harmful interference. This includes monitoring the transmitting frequency for communications in progress and such other measures as may be necessary to minimize the potential for causing interference. This all comes under the general heading of that the FCC calls “good operating practice,” which is basic common sense and courtesy. MURS stations are prohibited from operating as a repeater, signal booster, store-and-forward packet node, in continuous carrier (morse code) mode or as an interconnection with the public switched telephone network.

The big advantage of MURS over FRS is that you are allowed to use a more efficient, elevated antenna with “gain” to increase your useful “radio horizon” and range. At VHF frequencies antenna height is more important than transmitter power. The higher the antenna the better the reception. For two hand-held units on flat terrain, standing in the open without foliage, buildings or terrain obstructions, with both transceivers held at face level, theoretical line of sight is 5 miles. This is the best range you can hope for on without improved antennas.

If the transmitting station remains standing with the transceiver held at face level, but the receiving antenna is elevated 25 feet above ground, theoretical line of sight range approximately doubles to 11 miles. If the receiving station were standing on top of a 250 foot hill the line of sight range would be about 20 miles. The highest point of any MURS antenna is not allowed to be more than 60 feet above the ground or 20 feet above the highest point of the structure on which it is mounted. Using a 6dB gain vertical antenna, at maximum legal height, fed with low loss coax such as LMR400 on your home base, and having a 3dB gain 5/8 wave mobile antenna whip mounted up high on the roof of your vehicle, with a good ground plane, you can work mobile-to-base simplex from 10-20 miles, depending upon terrain.

The frequencies available in the Multi-Use Radio Service are:

Frequencies Authorized Bandwidth
151.820 MHz 11.25 KHz
151.880 MHz 11.25 KHz
151.940 MHz 11.25 KHz
154.570 MHz 20.0 KHz
154.600 MHz 20.0 KHz

MURS transmitters must be certificated in accordance with Part 95, Subpart J of the Commission’s rules. Business band land-mobile radio service radio units certificated prior to November 12, 2002 do not be re-certificated. You can buy used, surplus VHF “high-band” business radios and have a commercial 2-way radio shop program them for you into the MURS frequencies and legally use them without a license.

No MURS unit, under any condition of modulation, may exceed 2 Watts transmitter power output. This is not the handicap it may seem, because unlike FRS, there are no antenna restrictions. While it is illegal to use a VHF marine band radio on land, (read : antennas designed for the VHF Marine band are resonant at frequencies close to those used for MURS and usually work OK without retuning.

3 thoughts on “More Information on the MURS Radio system”

  1. I have 2 old 40 channel CB radios. Will they still work or is the frequencies given to different devices? Or easily modified for something different?

    Also I have an old 5 watt mobile telephone. Can this be used differently or modified, like as a RF power amplifier?

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