HTX-252 2-Meter Amateur FM Mobile Transceiver
(190-1127) Special Features Faxback Doc. # 60181
Continuous Tone Coded Squelch System Features
Your transceiver can transmit and receive a low-level, selectable
subaudible tone at the same time as it transmits (TX) or receives (RX) a
regular signal. This special tone lets you listen only to other
transceivers set to the same tone frequency when you use the transceiver
in simplex operation. It also lets you match your transceiver to the
subaudible tone frequency used by a local repeater.
To enable the TX and RX tones for the transceiver, follow these steps.
1. Press F+T-SQ. The current tone setting and T appear. (T indicates
that only the TX tone is enabled.)
2. Rotate the tuning control or repeatedly press UP or DN to select a
tone frequency from the list below. About 5 seconds after your last
change, the display exits the tone setting mode, stores your tone
selection, and the current operating frequency appears again.
3. To enable both the TX and RX tones, repeatedly press F+T-SQ until T-SQ
appears. To disable CTCSS operation, repeatedly press F+T-SQ until T
and T-SQ disappear.
4. Press PTT to store all the settings.
Temporarily Opening Squelch
If you use the Tone Squelch (CTCSS) feature, you might not hear a
transmission on the current frequency. To temporarily open the squelch so
you can hear all transmissions on the frequency, hold down F. To resume
normal operation, release F.
Subaudible Tone Frequencies (Hz)
67.0 88.5 110.9 136.5 167.9 210.7
71.9 91.5 114.8 141.3 173.8 218.1
74.4 94.8 118.8 146.2 179.9 225.7
77.0 97.4 123.0 151.4 186.2 233.6
79.7 100.0 127.3 156.7 192.8 241.8
82.5 103.5 131.8 162.2 203.5 250.3
85.4 107.2
Using DTMF Tones
DTMF (Dual-Tone, Multiple Frequency) is another term for touch-tones (the
tones a telephone produces when you press a digit). This standard set of
tones is used by many different amateur transceiver systems for accessing
programmable features and dialing through auto-patches to a standard
telephone.
Your transceiver produces all 16 standard DTMF tones (0-9,*,#,A,B,C,and D)
Follow these steps to use the DTMF feature.
1. Set DTMF on the bottom of the microphone to ON.
2. Enter the DTMF sequence using the alphanumeric keys.
3. After you complete your transmission, set DTMF to the left position to
turn off the feature.
Other Special Features
Using Priority Frequency Monitor
You can designate one frequency as primary (in either VFO or memory mode)
and another frequency as secondary (VFO only). Once you do that, the
transceiver tunes the primary frequency or memory location for 5 seconds.
Then it checks the secondary frequency for 1/2 second. If the transceiver
finds a signal on the secondary frequency, it automatically remains there
for 5 seconds before returning to the primary frequency.
Using VFO Priority
1. Select the desired secondary frequency using the tuning control or
UP/DN.
2. Press F + PRI (SCAN).
3. Select the primary frequency using the tuning control or UP/DN. The
transceiver starts to monitor both selected frequencies.
4. To disable priority monitor, press F + PRI (SCAN) again.
Using Memory Priority
1. Select the desired secondary VFO frequency using the tuning control or
UP/DN.
2. Press F + PRI (SCAN).
3. Press MR (MS) then select the desired memory location for your primary
frequency. The transceiver starts to monitor both selected frequencies
4. To disable priority monitor, press F + PRI (SCAN) again.
Changing The Transmit Frequency Range
You can change the standard transmit frequency range from 144-148 MHz to
an extended range of 142.000 - 149.885 MHz.
To set the transceiver to its extended range, turn it off. Then while
holding down F and LOCK, turn on the transceiver.
To return to the standard frequency range, repeat the above procedure.
Selecting The Transmit Power Level
You can select either of two transmitting power levels: high (25 watts)
for normal operation or low (10 watts). Choose the lower level to reduce
the possibility of overloading nearby receivers. Choose the higher level
when conditions warrant maximum transmitting power. To switch levels,
press F + PTT. If low is selected, LOW appears. If high is selected, LOW
disappears.
Locking The Keypad
To lock the transceiver's keypad so you do not accidentally change a
setting, press LOCK (SHIFT). (key symbol) appears. This locks all controls
except PTT, F, VOL, SQ, and LOCK.
To unlock the keypad, press LOCK again.
Turning The Key Tone On and Off
The transceiver is preset to sound a beep each time you press a key. To
turn off the beep, hold down the PTT button while you turn on the
transceiver's power. To restore the key tone, repeat the procedure.
Setting The Frequency Step
To change the frequency increment used during scanning and stepping to a
frequency, press F + STEP (CALL). The current frequency step appears. Then
repeatedly press UP or DN or rotate the tuning control to change the
setting. The default is 5 kHz. You can change the frequency step to 5 kHz,
10 kHz, 12.5 kHz, 15 kHz, 20 kHz, or 25 kHz.
Reducing Interference
Because your transceiver is exceptionally quiet, any noise you hear
probably originates from a source within your vehicle such as the
alternator, the spark plugs, or unshielded wires.
To solve the problem, you must locate the noise's source. You can
determine the noise's source by first turning off the engine and operating
the transceiver with your vehicle's ignition set to ACC. If the noise
decreases or disappears completely, the problem is with your vehicle's
ignition or associated wiring.
Here are a few suggestions to help you reduce or eliminate such noise:
Make all of the transceiver's power and antenna wires as short and as
direct as possible.
Route the power wires away from the antenna wires.
Be sure the chassis ground connection is secure.
Replace old ignition wires with new, high-voltage, noise suppression
wires.
Install noise suppressors on your spark plugs, or install new spark
plugs that have built-in noise suppressors.
If problems persist, check to ensure your alternator and electrical
system are operating correctly. You can reduce any noise by using bypass
capacitors at the various output voltage points.
Your local RadioShack store carries a wide selection of capacitors and
other appropriate noise reduction components.
(BR EB 6/14/00)