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Communications Information
- for use while birding,
etc. |
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Bob Ekblad |
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Radios for Birding |
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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.
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Radio Channel
& Frequency Relationships |
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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 |
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|
13 |
13 |
| 467.7125 |
0.5 |
FRS |
14 |
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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.
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Radio Models |
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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
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Motorola |
Talkabout |
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| GMRS |
Audiovox |
1545 (with Wx) |
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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.)
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Motorola |
T7200
(rated at 2 watts and 5 mile range)
T7100R (rated at 7 mile range) |
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Uniden |
GMR885 (rated at 8 mile range) |
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Most recent finds (August 2004) at the local Best Buy are indicated
above in bold (price range
was $65-$99)
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Antennas |
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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 |
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| The RF Connection |
Audiovox |
SMA female to BNC female |
$3 |
|
Cobra |
SMA male to BNC female |
$3 |
Vendor Information
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