Getting the Most from Your Personal Radio, MURS or FRS/GMRS

MURS

Here are a couple of MURS radios that I use all the time. They work great and give me 2 to 5 miles of range in the foothills where I live.

Here is an excellent article on the advantages of MURS radios for people who do not want to obtain a license for ham radios. It was sent to me by a friend from RACES. MURS stands for Multi-Use Radio Service.  After reading this post if you still have questions,  send them in and we will see if we can answer them with the help of some friends.

Howard

Getting the Most from Your Personal Radio

©1998-2015 Arlington County Virginia RACES, Inc.

The Multi-Use Radio Service (MURS) is better than FRS/GMRS for family and neighborhood emergency communications and does not require a license.   

If you don’t have a ham license, and the public service telephone network, cellular and internet are out of service, having portable 2-way radios among family and neighbors can be a life saver. If all you have is a “walkie talkie,” some basic radio knowledge will help you to “make the most of it!”

Popular FRS/GMRS “bubble pack” radios are wildly over-rated.  Advertising claims regarding  range are pure fantasy! Low-power FRS/GMRS UHF radios with a fixed antenna are only reliable from one-half to one mile in average urban terrain.

Reliable communication at ranges over a mile requires an unobstructed line of sight path without blocking buildings, foliage or terrain. FRS works fairly well if one person is up high, in the clear, on a hill talking to somebody in a valley below. But, if inside your car talking to others in a convoy, do not depend upon hearing each other unless you can actually SEE the other car.

If you are not interested in studying for and taking the exam for the Amateur Radio Technician license, http://www.arrl.org/getting-licensed the best option for local emergency communication within a few miles, is the Multi-Use-Radio Service or MURS. The Business Pool VHF frequencies formerly known as the VHF “color dot” frequencies were moved 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.

MURS is ideal for neighborhood and family emergency communications. No license is needed. Anyone may operate an MURS transmitter if they are not a foreign government or a representative of one and they use the transmitter in accordance with the rules. This means no illegal activity, no profanity, be an adult and play nice. MURS users are not required to transmit a station identification announcement or “callsign.”

The MURS channels authorized are available on a shared basis only. Users must cooperate in the selection and use of channels in order to reduce interference and avoid interference to others. Around cities you may hear warehouse operations, landscapers, trash collection, building maintenance and construction site crews. The wide-band FM channels 154.57 and 154.60 get more use than the 151 Mhz. narrow-band ones.

MURS operation is authorized anywhere CB allowed, but is NOT authorized aboard aircraft in flight.  Unlike FRS and GMRS, MURS users may use either voice or data signals, including digital selective calling or tone-operated squelch tones to establish or continue voice communications, remote control and telemetering functions, except that CW or “Morse code” is not permitted.

MURS users are required to take reasonable precautions to avoid causing interference. This comes under what the FCC calls “good operating practice,” which is essentially common sense and courtesy. MURS cannot be used as a repeater or signal booster, including “store-and-forward” packet operation or interconnection with the publicly switched telephone network.

The greatest advantage of MURS over FRS is that you can 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 transmit power.

The higher the antenna, the better the reception. For two users with portables on flat terrain, standing in the open without foliage, buildings or terrain obstructions, with both radios held at face level, theoretical line of sight is 5 miles, which is the best range you can hope for in direct simplex without improved antennas.

If a person transmitting remains standing with the transceiver held at face level, but the receiving antenna is elevated 25 feet above ground, line of sight range approximately doubles to 11 miles. If the receiving station were standing on top of a 250 foot hill the theoretical line of sight range would be about 20 miles.

The highest point of an MURS antenna is not allowed to be more than 60 feet above ground or 20 feet above the highest point of a structure on which it is mounted.

Frequencies of 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 radios must be certified in accordance with Part 95, Subpart J of FCC rules. Business band VHF LMR radios which were type-accepted prior to November 12, 2002 do not be re-certified.

While low cost Chinese radios are widely advertised through Amazon and other outlets, cheap radios do not have the reliability, ruggedness or durability of professional-grade Land Mobile Radio service (LMR) portables. Do you want to stake your life on a “bubble pack “toy” radio?  Sorry, wrong answer! You can readily buy professionally refurbished LMR portables reprogrammed into the MURS frequencies in the $120-200 range and legally use them without a license. This link is for a reliable seller which we have used and this package includes all of the necessary ancillary equipment that you will need:

http://www.reddogradios.com/icom-ic-f3s-vhf-portable-radio-kit-refurbished.html 

No MURS unit in any condition of modulation, may exceed 2 watts of transmitter power output. This is not the handicap it may seem, because unlike FRS, the only antenna restrictions is mounting height if a base antenna is put on a structure.

While some prepping sites have suggested using VHF marine radios, it is illegal to use VHF a marine band radio on land, read the info at: http://www.mcminnarc.com/marine.html But ANTENNAS designed for the VHF Marine band are resonant at frequencies close to those used for MURS and usually work OK without any retuning and are worth shopping for. A 3dB gain, 5/8 wave whip antenna on your vehicle doubles the effective radiated power of your portable radio.  Putting a 6dB gain base station vertical antenna on the chimney cap of your house, or above the highest point on the structure quadruples effective radiated power.

Keep your portable radio antenna as high as possible and in the clear.  Carrying a portable on your belt and using a speaker microphone causes produces -20dB of attenuation, reducing your 2-watt MURS radio effectively to only 20 milliwatts!

Flexible antennas used on portable radios are rubber covered helical springs, intended to withstand rough handling, but they are not indestructible.  Flexible VHF antennas used on California fire lines for several weeks showed a 60% failure rate.

Flexible antennas should be replaced as soon as they show ANY apparent kinks, cracks, abrasion or other wear to visual inspection.  You should always carry a spare antenna of some type.

An expedient which improves performance of a flexible antenna is a counterpoise (18″ long for MURS or 6” for GMRS) of stranded wire, crimped and soldered to a flat ring terminal which is sandwiched between the antenna connector and radio chassis. Reinforce the soldered connection with heat shrink to resist flexing.

The counterpoise prevents transmitted RF from coupling with your body, so that your antenna now performs like a center-fed dipole, instead of an “end-fed dummy load!”  The main lobe of the radiation pattern can also be “aimed” by, grasping and pointing the end in the direction where you need a stronger signal. 

After-market full-sized, flexible 1/4 wave and telescoping 1/2-wave Marine VHF and “high band” VHF LMR portable antennas work well for the MURS.  A quarter-wave antenna provides unity gain when used with a counterpoise and held at face level. This represents a 5 dB improvement over a typical short flexible antenna, because most of its effective signal is radiated. If operating from your vehicle, connect your portable radio to a magnetic mount antenna centered on the vehicle roof to provide a clear RF path outside the vehicle.  This overcomes about -10dB attenuation which results from operating a portable radio inside a metal vehicle.  Two-way radio shops can provide suitable adapters so that you can connect your MURS portable to an outside base or mobile antenna.

Pre-position antennas, coaxial feed line and adapters at shelters, etc. for this purpose.

In marginal operating locations a telescoping, half-wave antenna performs better than a short helical, because it provides the same unity gain without a ground plane that a 1/4 wave antenna does when used with a ground plane. A half-wave antenna can be pulled up into a tree, dangled out a window, attached to a window pane with suction cups, or be used bicycle or motorcycle mobile, or in city driving on a window clip mount.

A telescoping half-wave increases useable simplex range of a typical 2 watt, MURS portable in average suburban ground clutter from less than 1 mile with flexible antenna to about 2 miles or more, depending upon antenna height relative to terrain.

Adding a counterpoise to a unity gain antenna enables you to keep in reliable contact within 3-5 miles to a mobile or base equipped with a gain antenna, depending upon terrain and ground clutter.

Telescoping antennas half-wave antennas give good performance, but are more fragile and work best when stationary or in the open.  Avoid side impacts, rough handling or prolonged mobile use of telescoping antennas on window clip mounts at highway speed, because frequent flexing loosens their internal electrical connections.  Never collapse a telescoping antenna by whacking it down with the palm of your hand. Gently pull it down with your fingers.  If you note any wobbling or looseness in the sections, replace the antenna.

Flexible antennas are safest when working in close quarters around people and are more durable when walking through dense vegetation for wildfire suppression, damage assessment, CERT or search and rescue operations. How efficient a particular antenna is can be determined only by testing.  A telescoping half-wave, or end-fed half-wave mobile antenna with magnetic mount, which will work either with or without a ground plane, offers the best “bang for the buck.”  

A magnetic mount works best on a car, but an improvised ground plane can almost always be found around the home or office, such as a metal filing cabinet, metal trash can, cookie sheet, rain gutter, refrigerator, window air conditioning unit, balcony railing or any other large metal object.

On boats, motorcycles, fiberglass truck caps or wooden balcony railings use a half-wave antenna, which does not require a ground plane. If you need to place an antenna on a bus or other vehicle where a mag mount won’t work, use a suction cup mount:

How to information here:

http://www.w5fc.org/pse_docs/KNOWLEDGE/qst_p56.pdf 

A common error of portable radio owners is failure to carry enough batteries to last through the storm.  The planning standard used by public safety professionals is a 12-hour “operational period.”  As a minimum carry at least one spare charged battery pack and a AA battery case, which enables you to keep operating if the AC power goes off, so you can’t recharge.

Cycle and recharge dry NiCd or NiMh packs monthly. Write the recharge date on a strip of tape on each pack.  In cold weather keep NiCd packs warm by keeping them in an inside coat pocket and not exposed on your belt. Do not store NiMh packs in your vehicle above 120 degs. F if you expect them to hold charge more than a few hours.

An adapter cord to power your transceiver from an auto cigarette lighter plug or a gel cell battery is needed for extended operation.

Cigarette lighter cords are often unreliable because auto sockets aren’t the best conductors, due to contamination and size variations, which cause the plug to vibrate loose.  As alternate power, they are good to have, because they are ubiquitous and much better than nothing!

If all you have is a portable transceiver, the above information will help to ensure that you can provide an adequate signal for reliable emergency communications.

Doing so is vitally necessary to enable your Citizen Corps or other volunteer disaster unit to complete its mission efficiently and safely.

More information on emergency communications is available at the Arlington (VA) Radio Public Service Club web site at  http://www.w4ava.org

©1998-2015 Arlington County Virginia RACES, Inc

 

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