Operating instructions

8 Choosing a Ham Radio
can also be charged in a vehicle with an automotive adapter. An automotive adapter that
allows your handheld radio to charge (and possibly operate) from a vehicle’s cigarette
lighter or other 12-volt source is useful if ac power is unavailable. Not all handheld radios
can transmit while connected to chargers—be sure to check the manual!
Radios for base, portable, or mobile use require an external power source. This may be
a vehicle’s electrical system, a deep-cycle battery, or an ac-operated power supply. Mobile
radios may require up to 20 amps on transmit at full power, so be sure your power source
can deliver enough current.
Power supplies and the cables used to connect the radio must be able to supply the
maximum required current for your radio at the proper voltage. Check the radio’s specifi-
cations for input current to find out how much current is needed. The radio manual should
also specify what wire size for a given cable length is needed to insure adequate voltage at
the radio under full load.
squelch aNd ToNes
Squelch is the circuitry in FM radios that prevents the user from having to listen to noise
or unwanted signals by muting the radio’s audio output unless the proper type of signal
is received. The radio’s manual will explain how to use a squelch level control knob (like
the typical knob in the illustration) or menu setting, common on pocket-sized handhelds.
These are the different types of squelch and associated features:
• Carrier squelch, the simplest and most common type of squelch, mutes the radio when
no signal stronger than a preset settable threshold is present.
• Tone receive squelch requires a specific sub-audible tone for the received audio to be
“Wallwart”Charger
(rechargesslowly)
Figure2
“Drop‐in”DesktopCharger
(rechargesquickly)
Automotiveadapter
Forvehiclepower
Figure2—Handheldradiosaresoldwithawall-mountedsupplyor“wall wart ”thatcharges
thebatteriesslowly.Adeskor drop-in chargerchargesthepacksquicklyandholdstheradio
upright.Iftheradiocanchargefrom12V,itcanalsobechargedinavehiclewithanautomo-
tive adapter.