Subj : Todays New Gear Tip
To   : All
From : Daryl Stout
Date : Sun Oct 08 2017 12:05 am

Frequencies And Modes 

If your interest lies primarily in using the local FM repeaters and
simplex channels, information about what frequencies are most used is
available from local radio clubs and newsletters, the local frequency
coordinator's Web site, the ARRL Repeater Directory
(www.arrl.org/catalog), and emcomm teams. Ask about the coverage
(range) of the repeaters, as well. 

The most popular VHF/UHF radios for FM voice and data are dual-band,
meaning that they can transmit on both the 2 meter (144-148 MHz) and
70 cm (420-450 MHz) bands.

Higher-end units allow you to monitor several bands at once and listen
on one band while transmitting on the other. 

Whether you need the radio to cover the 50 MHz, 220 MHz or 1.2 GHz bands
will depend on activity in your area. The first two are often used 
by emcomm teams and the last is more likely to be used in densely
populated areas. Cross-band repeater capability (receiving on one band
and retransmitting the signal on the AM Broadcast 550 kHz to 1.8 MHz
other band) is a "nice-to-have", but not commonly needed.

Receiver coverage comes in three flavors.

"Ham band receive" can tune all of the ham bands, plus narrow ranges 
above and below the band edges for amateur auxiliary services, such as
MARS. "Extended receive" includes reception of selected frequency ranges
such as those in the PDF file.

"Wideband receive" covers a wide range of continuous Marine 156 to 158
MHz frequencies; good for using the radio as a scanner. Being able to
receive commercial broadcasts and non-ham services is very helpful
during emergencies although this capability may make the receiver more
susceptible to overload and interference from strong nearby transmitters. 

Caution - even though some VHF/UHF amateur radios with wideband receive
can tune in AM broadcast, shortwave broadcast (SW BC) and aviation AM
signals, most cannot receive SSB or CW signals and thus are unsuitable
for use on the HF ham bands. Receiving VHF AM aviation signals
(sometimes called airband) is also handy for tracking down and
identifying sources of interfering noise, such as from power lines or
appliances. You can find out more about what stations are on what
frequencies by browsing online frequency lists such as:

www.panix.com/clay/scanning/freq-lists.html.

Many municipal and government systems use trunking systems in the VHF
and UHF bands. (Trunking systems share a few channels among many users
by changing the frequency of individual radios under the control of a
central station.) These can not be received by ham radios or scanners
without trunking features.


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