HTX-404 440 MHz UHF FM Transceiver
(190-1140) Operation Faxback Doc. # 46639
This section has the basic information you need to use your HTX-404.
Setting Squelch and Volume
Rotate VOLUME clockwise and SQUELCH counterclockwise until you hear a
hissing sound. Then slowly rotate SQUELCH clockwise until the noise stops.
Leave VOLUME set to a comfortable level.
If the HTX-404 picks up unwanted weak transmissions, rotate SQUELCH
clockwise to decrease the HTX-404's sensitivity to signals.
Selecting a Frequency
You can use any of three methods to select a frequency.
Direct entry.
Tune control.
Scanning for frequencies.
Tuning Using Direct Entry
Your HTX-404 transmits and receives on frequencies between 440.000 and
450.000 MHz unless you activate additional frequencies (see "Activating
Additional Frequencies"). To quickly tune to a frequency, enter the
frequency using the keypad.
1. Turn on the HTX-404.
2. Press VF.
3. Use the keypad to enter the last five digits of the frequency. For
example, to enter 446.940, press 46940.
Notes: If you make a mistake, press CLR and repeat Step 3.
The HTX-404 rounds the last digit down to 0 or 5.
Tuning Using the Tune Control
You can quickly tune to a nearby frequency by rotating TUNE on top of the
HTX-404.
1. Turn on the HTX-404.
2. Press VF.
3. Rotate TUNE counterclockwise to tune down or clockwise to tune up. The
HTX-404 tunes down or up one frequency step per click. To change the
frequency step, see "Setting the Frequency Step Rate".
Scanning for Active Frequencies
You can search for activity on a frequency by pressing and holding down
/\SC or \/SC for at least 1 second. The HTX-404 begins to scan up or down
the full frequency range, and stops on active frequencies. To scan only a
selected frequency range, press F + /\ SC or F + \/ SC. See "Setting Scan
Options" to see how to change the scanning range, the frequency step, the
scan resume condition, and the scan delay time. The following are the
factory presets for these options.
Frequency Step: ................................................... 20 kHz
Scan Resume Condition: ................... Resumes scanning in 10 seconds,
regardless of absence or presence
of carrier.
Scan Delay: ............................................... Not activated.
Scan Limits: .......................................... 440 MHz to 450 MHz
To stop scanning, press /\SC, \/SC, CA, PR, MR, VF or turn off the HTX-404
Scanning for a Vacant Frequency
In some areas where the 440 MHz band is used heavily, you might have
trouble quickly finding a frequency not being used. To quickly scan for a
vacant frequency, press F + V - SC. The HTX-404 scans up or down from the
current frequency to the first unused frequency. To change the vacant scan
direction, see "Vacant Scan Direction."
Receiving Transmissions
To receive transmissions, turn on the HTX-404, adjust the volume and
squelch and tune to a frequency.
Transmitting
There are two basic types of communications you can use with this HTX-404.
These are referred to as simplex and duplex.
With simplex transmission, you transmit and receive on the same frequency,
and are usually communicating with a station within a couple of miles of
your location.
Duplex transmission is what you use when you communicate using a repeater.
You transmit to the repeater on one frequency (the input frequency), and
the repeater retransmits the signal at a different frequency (the output
frequency). Since repeater antennas are usually located on radio towers,
tall buildings or mountains, you can hit a repeater from much further away
than other mobile of fixed stations. This lets you talk to stations much
further away.
CAUTION: Do not transmit if you do not have a Technician Class or higher
license issued by the FCC. Doing so is illegal.
Follow these steps to communicate using simplex communications.
1. Turn on the HTX-404.
2. Select the desired frequency.
3. If (+) or (-) is on the display, repeatedly press F + + / - until
neither symbol appears.
4. Press LOW POWER so the button is down. In this position, your HTX-404
transmits at about 1 watt.
5. Begin communication.
If the other party advises that you need to improve your signal, press LOW
POWER so the button is up. In this position, your HTX-404 transmits at the
highest power it can, depending on the power source. See "Power Sources"
or "Specifications" for these levels. Remember to switch back to low power
whenever possible, to comply with the FCC rules that require you to use
the minimum power necessary to maintain communications.
Follow these steps to communicate using duplex communications (through a
repeater).
1. Turn on the HTX-404.
2. Tune to the desired receive (output) frequency.
3. If transmit (repeater's input) frequency is 5 MHz above the receive
(repeater's output) frequency, repeatedly press F + + / - until +
appears in the display. If the transmit frequency is 5 MHz below the
receive frequency, repeatedly press F + + / - until - appears on the
display. If the frequency separation is not 5 MHz, either set a new
default frequency separation or store the frequency pair in one of the
scanner's memories.(See "Using Memory Channels" and "Duplex Separation
Default".)
Locking The Keypad
To lock the HTX-404's keypad so you do not accidentally change a setting,
press F + LOCK. LOCK appears on the display. This locks all front-panel
buttons and the tune control. PTT, VOLUME and SQUELCH still operate. To
release the lock, press F + LOCK again.
Setting The Key Entry Beep
Each time you press a key, the HTX-404 sounds a beep. To turn off the
beep, press F + BEEP. The key beep does not sound for this or subsequent
key presses. To turn on the key beep, press F + BEEP again.
Reversing The Offset
To reverse the transmit and receive frequencies when you are operating
duplex, press F + REV.
For example, if you are set to 449.940 with a - offset, pressing F + REV
makes the HTX-404 receive on 444.940 and transmit on 449.940.
(EB 3/3/98)