RadioShack FM Mobile Transceiver HTX 252 Owners Manual

							11
CONNECTING AN ANTENNA
You must install an antenna before you can operate the trans-
ceiver. There are many different types of antennas suitable for
transceiver use. Each has its own benefits, Choose the one best
suited to your particular needs. Your local RadioShack store has
a wide selection from which to choose.
Note: If you are using the transceiver as a base station, see “Us-
ing the Transceiver as a Base Station” on Page 13.
When you install an antenna, keep in mind that, for the best per-
formance, you should mount the antenna vertically as high as
possible on the vehicle and away from sources of electrical noise.
Once you choose an antenna, follow it’s mounting instructions.
Then route the cable to the transceiver and thread the cable onto
the 
ANT connector on the back of the transceiver.
Cautions:
• Avoid routing the cable next to sharp edges or moving
parts, which might damage the cable.
• Do not run the cable next to power cables or other radio
antenna cables.
• Do not run the cable through the engine compartment or
other areas that produce extreme heat.
To take advantage of your transceiver’s maximum range, adjust
the antenna’s standing wave ratio (SWR) using an SWR meter
(not supplied, available at your local RadioShack store). Follow
the instructions supplied with the SWR meter and antenna to ad-
just the antenna’s SWR. Values of 2.0:1 are generally accept-
able, with readings of 1.5:1 or lower being more desirable. 
						

							12
CONNECTING THE MICROPHONE
1. Align the notch of the
microphone’s plug and
the microphone’s jack,
located on the left side of
the front panel. Then
insert the plug and turn
the metal ring clockwise
to secure the plug.
2. Slide the microphone onto the microphone holder.
To disconnect the microphone from the transceiver, turn the met-
al ring counterclockwise to loosen it.
Caution: Always disconnect the microphone by grasping its plug.
Never pull on the coiled microphone cable.
USING AN EXTERNAL SPEAKER
To hear your communications better in a noisy environment, you
can plug an optional, external speaker into the transceiver. The
speaker should have an impedance of 8-ohms and be able to
handle 3 to 10 watts of power. The speaker’s cable should have
a 
1/8-inch (3.5-mm) plug.
To connect the speaker, insert the speaker cable’s plug into 
EXT.
SP
 on the back of the transceiver. This automatically disconnects
the built-in speaker.
MHz
F
DTMF ON CALL
STEPSCAN
PRILock
SHIFT 
						

							13
CONNECTING POWER
Follow these steps to power the transceiver from your vehicle’s
battery.
1. Connect the supplied polarized
13.8V DC power connector to
the white power socket and
cable on the back of the trans-
ceiver. The plug and socket only
fit one way. If you can not easily
insert the plug, turn it over and
try again. Do not force it. 
2. Connect the red wire (+) (with
the in-line fuse holder) to a point in your vehicle’s fuse block
that supplies power only when the ignition is in the ACC
(accessory) or ON position.
3. Connect the black wire (–) to a metal part of the vehicle’s
frame (chassis ground).
Caution: Do not connect the black wire to a non-metallic
(plastic) part, or to any part insulated from the vehicle’s
chassis by a non-metallic part.
USING THE TRANSCEIVER AS
A BASE STATION
Although this transceiver is designed for mobile use, you can also
use it as a base station with a DC power source. To use the trans-
ceiver as a base station, you need these items:
• a regulated power supply that supplies at least 7 amps at
12V DC
Caution: Most 12–13.8V DC power supplies operate from a
standard AC outlet. Before connecting your transceiver to
this type of power supply, read and follow the instructions
included with it. 
						

							14
• a base station antenna
• coaxial antenna cable and appropriate connectors
Your local RadioShack store carries a wide selection of all prod-
ucts needed to set up your transceiver as a base station.
Follow these steps to use the transceiver as a base station.
1. Mount the base station antenna as described in its owner’s
manual.
Warning: Use extreme caution when you install or remove
a base station antenna. If the antenna starts to fall, let it go!
It could contact overhead power lines. If the antenna
touches a power line, contact with the antenna, mast, cable,
or guy wires can cause electrocution and death. Call the
power company to remove the antenna. Do not attempt to
do so yourself!
2. Connect the antenna to the PL259 
ANT connector on the
back of the transceiver. If the antenna’s plug does not match
the 
ANT jack on the back of the transceiver, contact your
local RadioShack store for a suitable adapter.
3. Connect the supplied polarized 13.8V DC power connector
to the white power socket and cable on the back of the
transceiver. The plug and socket only fit one way. If you can
not easily insert the plug, turn it over and try again. Do not
force it. Then connect the red power wire with the in-line
fuse (+) and the black power wire (–) to the appropriate ter-
minals on your power supply.
4. Plug the power supply’s AC power cord into a standard AC
outlet. 
						

							15
A QUICK LOOK AT THE CONTROLS
Most of the controls on the transceiver have multiple functions.
The following charts should help you get a better idea of the func-
tion of each control.
Base Unit
Key/Control Use it to:Use with the 
F + Key to:
OFF/VOL
Turn the transceiver on/
off. Adjust the volume.Reset the
transceiver
SQ
Set the squelch level to 
block weak signals.N/A
REV
Reverse the
repeater offset.N/A
 VFO (T-SQ)
Set the transceiver to 
VFO mode.Set the tone 
squelch.
MR (MS)
Recall a frequency in
memory.Store a frequency
in memory.
Tuning Control
Change the frequency 
by the set STEP value. Change the
frequency by 1 MHz 
steps.
OFF/VOL  Tuning Control
SQ  REV  VFO MR
(T-SQ) (MS) 
						

							16
Microphone 
Key/Control Use it to:Use with the 
F + Key to:
Push to 
Talk (PTT)Transmit by holding it 
down. Press to store a 
setting.Change the transmitting 
power to high or low.
UP
Increase the fre-
quency by the selected 
step value.Increase the frequency 
in 1 MHz steps.
DN
Decrease the fre-
quency by the selected 
step value.Decrease the frequency 
by 1 MHz steps.
 F (MHz)
Temporarily open the 
squelch.N/A
CALL 
(STEP)Recall the calling fre-
quency memory.Set the frequency step.
PTT
DTMF
F (MHz)
CALL
(STEP)SCAN
(PRI)
LOCK
(SHIFT)
 DN
UP 
						

							17
SCAN (PRI)
Start and stop 
scanning.Set the transceiver to 
dual watch mode.
LOCK 
(SHIFT)Lock and unlock the 
controls except PTT
, F
, 
VOL
, and SQ
. Set the repeater
offset.
Alpha-
Numeric 
KeysEnter numerical val-
ues and DTMF control
letters.N/A
DTMF
Switch to DTMF
control.N/A Microphone 
Key/Control Use it to:Use with the 
F + Key to: 
						

							18
A QUICK LOOK AT THE DISPLAY
1.  — appears when 
F key is pressed.
2.  — indicates the keypad is locked.
3.  — indicates a negative repeater offset.
4.  — indicates a positive repeater offset.
5.
SCAN — appears when the transceiver is scanning frequen-
cies.
6.
PRI — indicates a priority frequency.
7.
T — appears when Tone Squelch (CTCSS) is enabled for
transmission only. 
8.
T-SQ — appears when Tone Squelch (CTCSS) is enabled
for both transmission and reception.
9.
Alpha-Numeric Display —
 shows frequency and operation
feature information.
10.
TX — appears when the transceiver is transmitting.
11 .
0 to 9 — shows the memory channel in use.
12.
BUSY — appears when the transceiver receives a signal.
13.  — indicates signal strength; the stronger the
signal, the more boxes appear. 
14.
ME — appears when the frequencies and other station data
are being stored or while scanning data in memory loca-
tions.
Note: When you reset the transceiver, all display elements ap-
pear. See “Resetting the Transceiver” on Page 37.
FUNC 
						

							19
OPERATION
TURNING THE TRANSCEIVER 
ON AND OFF
To turn on the transceiver, rotate VOL clockwise until it clicks. The
last used frequency and other settings appear (the default fre-
quency is 142.50 MHz, with a frequency step of 5 kHz/.005 MHz).
To turn the transceiver off, rotate 
VOL counterclockwise until it
clicks.
SELECTING FREQUENCIES
To select a frequency in the VFO (variable frequency oscillator)
mode, use either 
UP or DN on the top of the microphone or the
tuning control.
Using either method lets you step up or down in increments which
you set using the Frequency Step option. (See “Setting the Fre-
quency Step” on Page 33“).
Rotating the tuning control changes the frequency by the value of
the step you set. You might want to set your preference for the
step value before you make other settings. Repeatedly pressing
(or holding down) 
UP or DN also changes the frequency by the
step value. To change the frequency by 1MHz steps, press 
F so
 appears. Then repeatedly press or hold down 
UP or DN.
The displayed frequency is typically shown to two significant dec-
imal places. However, depending upon the selected frequency
step, you might see a smaller number displayed to the right of the
second place. For example, 
142.50
75 lets you see the complete
frequency in use if you select 12.5kHz as your frequency step.
FUNC 
						

							20
RECEIVING TRANSMISSIONS
Follow these steps to receive standard transmissions.
1. With the transceiver on, rotate 
SQ counterclockwise until
you hear a hissing sound. Then slowly rotate 
SQ clockwise
just until the noise stops.
Notes: 
•
BUSY appears when the transceiver receives a standard
transmission or if the squelch is open.
• If the transceiver picks up unwanted and weak transmis-
sions, rotate 
SQ clockwise to prevent the squelch from
opening for these transmissions. If you want to hear
weak transmissions, rotate 
SQ counterclockwise. When
you do this, you might hear hissing between transmis-
sions.
2. Rotate the tuning control to select a frequency.
3. Set 
VOL to a comfortable listening level.
TRANSMITTING
There are two basic types of communication possible with this
transceiver: radio-direct-to-radio (simplex) or radio-to repeater-to
radio (duplex). Simplex operation uses the same frequency to
send and receive. Duplex operation uses one frequency to trans-
mit and another to receive. For more information about duplex,
see “Understanding Repeaters” on Page 22.
Caution: It is illegal to transmit if you do not have at least a Tech-
nician Class license issued by the FCC.
Follow these steps to transmit.
1. Select the desired frequency using the tuning control or 
UP/
DN until you are within the transmit frequency range.