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Communications Information - for use while birding, etc.

Bob Ekblad


   Radios for Birding 

There are two handheld radio types that are emerging as replacements for Citizen Band (CB) radios as the choice of birders for communicating with one another while out in the field.
  • The Family Radio Service (FRS) radio, which requires no license, is limited to 1/2 watt of power output which generally limits the range of use to less than two miles.
  • The General Mobile Radio Service (GMRS) radio, which does require a license to operate, is allowed up to 5 watts of power output.  Most handheld GMRS radios on the market today operate with a max power of about 2 watts (with a typical range of up to about 5 miles).  Some radios are now showing up with 3 watt ratings and touting a 7 mile range).  The maximum wattage is generally limited due to battery restrictions. If you want further information on how to obtain a license to transmit on GMRS, click here .
  • For more information on rules and requirements for FRS/GMRS radios, see the FCC web site
These radios operate on frequencies in the 462 MHz range (CB frequencies are in the 27 MHz range).  They are not as likely to have problems with interference as experienced with CB radios.  However, radios operating at these frequencies work best with direct line-of-sight operation.  The range can be significantly reduced when there are buildings, terrain, or other objects that block the path of the signal.

Most radios designed for use in the FRS/GMRS frequency band started out with 15 or so channels that can be used for communications, the first seven of which are common between the GMRS and FRS radios (allowing communication between the two different radio types).  Newer radios are now available that have 22 channels (7 FRS limited to 1/2 watt output, 8 FRS/GMRS and 7 GMRS channels).

Most of these radios have subcodes (interference filters) that can be used as a filter to block reception of other signals on the channel and allow only those on that subcode to be heard.

The ABA suggests the use of FRS channel 11 with subcode 22.  However, this excludes the use of the more powerful GMRS radio.  Many of the people with GMRS radios in Minnesota use channel 6 with subcode 6 which allows both FRS and GMRS to be used to communicate.



  
Radio Channel & Frequency Relationships

If you use different brands of radios or radios with different numbers of channels, you may need to operate them on different channels if you want to communicate between them.  The following chart is a compilation of some of the radio frequencies and channels for some manufacturers.  This is not a complete list but it may be helpful in determining which channel(s) to use, or at least as a starting point in testing to find the right channel to use.  Be aware that the sub-code channels may also be different for the different manufacturers, so testing is advisable prior to use.
Frequency
Max Watts FRS GMRS 22 channel
Cobra
15 channel
Cobra
15 channel
Audiovox
15 channel
RadioShq
14 channel
RadioShq
22 channel Motorola
462.5625 5.0 * Both 1 1 1 1 1 1
462.5875 5.0 * Both 2 2 2 2 2 2
462.6125 5.0 * Both 3 3 3 3 3 3
462.6375 5.0 * Both 4 4 4 4 4 4
462.6625 5.0 * Both 5 5 5 5 5 5
462.6875 5.0 * Both 6 6 6 6 6 6
462.7125 5.0 * Both 7 7 7 7 7 7
467.5625 0.5 FRS 8       8 8
467.5875 0.5 FRS 9       9 9
467.6125 0.5 FRS 10       10 10
467.6375 0.5 FRS 11       11 11
467.6625 0.5 FRS 12       12 12
467.6875 0.5 FRS 13       13 13
467.7125 0.5 FRS 14       14 14
462.5500 5.0 GMRS 15 11 11 8   15
462.5750 5.0 GMRS 16 8 8 9   16
462.6000 5.0 GMRS 17 12 12 10   17
462.6250 5.0 GMRS 18 9 9 11   18
462.6500 5.0 GMRS 19 13 13 12   19
462.6750 5.0 GMRS 20 10 10     20
462.7000 5.0 GMRS 21 14 14 13   21
462.7250 5.0 GMRS 22 15 15 14   22
Information above is pertinent to the specific radio  shown here -> PR4000
3W GMRS
  1535
2W GMRS

5 W GMRS

0.5 W FRS
T5000
1W GMRS
      * Max of 0.5 watts if it is only a FRS radio.
   Radio Models

There are several manufacturers that sell both GMRS and FRS radios.  Several of these include weather channels (Wx).  The radios most commonly seen in retail stores are:
FRS Cobra Microtalk
  Motorola Talkabout



GMRS Audiovox 1545 (with Wx)
  Cobra PR4000 (rated at 3 watts and 7 miles range - includes Wx and a bunch of other goodies)
PR4300 (rated at 10 mile range - includes Wx, etc.)
  Motorola T7200 (rated at 2 watts and 5 mile range)
T7100R
(rated at 7 mile range)
  Uniden GMR885 (rated at 8 mile range)



Most recent finds (August 2004) at the local Best Buy are indicated above in bold (price range was $65-$99)


   Antennas

Most of the time you would probably want to operate with the rubber ducky antenna that comes with the radio, but there may be times when you might expect to be using the radios in the car where an external magnetic mount antenna might be useful.  With the FRS radio this is not possible since the rubber ducky antenna on those units is hardwired to the radio and cannot be replaced.  The GMRS radios usually have a screw off rubber ducky that can be replaced with a coax cable that connects to a mag mounted antenna on the roof of your car. 

There is a mag mount antenna that is designed for use at 462 MHz that can be purchased for this purpose.  Others may be available as well.
Advantage Communications PR1000MagMobAntenna
 5dB Gain with 12 ft cable
 (Comtelco Industries, Inc
   501 Mitchell Road
   Glendale Hts, IL 60139)
$39.00

This antenna comes with a coaxial cable terminated with a BNC connector.  Since the GMRS radios have different connectors for their rubber ducky antennas, an adapter is required to connect from the radio to the BNC connector. 
Adapter Sales Radio Mfg  Adapter
Advantage Communications Cobra SMA male to BNC female $12
       
The RF Connection Audiovox SMA female to BNC female $3

Cobra SMA male to BNC female $3

Vendor Information

Advantage Communications
1-800-294-7234
1-617-926-8650
1-301-869-3680 Fax
PO Box 282
Watertown, MA 02471-0282
Web site: www.scoden.com
Web site: www.radiosonline.com
The RF Connection
1-800-783-2666
1-301-840-5477
213 N. Frederick Ave #11
Gaithersburg, MD 20877-2435
Web site: www.therfc.com