We are grateful you decided to purchase this TC-245DX FM transceiver. This series of handhelds was
developed to satisfy the requirement for a compact rig that’s simple to operate yet contains multiple
new features. TC-245DX believes that the compact size, coupled with reasonable cost, will meet your
This transceiver has the following main features.
Contains a total of 80 memory channels programmable with 50 CTCSS and other various data.
Illuminates the keys on the keypad as well as the display to permit easy operation in the dark.
Please observe the following precautions to prevent the transceiver damage:
Do not modify this transceiver unless instructed by this manual or by TC-245DX documentation.
Do not expose the transceiver to long periods of direct sunlight nor place the transceiver close to
Do not place the transceiver in excessively dusty areas, humid areas, wet areas, nor on unstable
If an abnormal odor or smoke is detected coming from the transceiver, turn OFF the power
immediately and remove the battery pack from the transceiver. Contact a TC-245DX service station
or your dealer.
TURNING TRANSCEIVER ON/OFF
1. Turn the power switch clockwise to turn ON the transceiver.
A beep sounds.
2. To turn OFF the transceiver, turn the power switch counterclockwise again.
1. Turn the VOL control clockwise to increase the audio level and counterclockwise to decrease the
If background noise is inaudible because of the squelch function, press and hold [MONI] key,
then turn VOL control. While pressing [MONI] key, you will hear the background noise.
The purpose of the Squelch function is to silence background noise output from the speaker (squelch
closed) when no signals are present. When the squelch level is set correctly, you will hear sound
(squelch opened) only while a station is actually being received.
The current squelch level appears.
2. Use the [UP], [DOWN] key to select the squelch level from 0 to 9.
Select just the level at which the background noise is eliminated when no signal is present.
The larger the level number you select, the stronger the signals you need to receive to hear.
3. Press any key other than [LAMP] and [MONI] to complete the setting.
1. Use [UP] key to increase the channel number, and [DOWN] to decrease.
You can also select your desired channel number with the numeric keys. See “KEYPAD
1. When ready to begin transmitting, press and hold the [PTT] switch and speak in a normal tone of
The On Air lamp lights red.
Speaking too close to the microphone, or too loudly, may increase distortion and reduce
intelligibility of your signal at the receiving station.
2. When you finish speaking, release the [PTT] switch.
If your transceiver seems to be malfunctioning, initializing the transceiver may resolve the problem.
Remember that you need to re-program memory channels after initialization. On the other hand,
initialization is a quick way to clear all memory data.
Full Reset (Memory)
Use to initialize all settings.
1. Press [F] + POWER ON.
A confirmation message appears.
To quit resetting, press any key other than [F].
2. Press [F] again.
Scan is a useful feature for hands-off monitoring of your favorite frequencies. After becoming
comfortable with how to use all types of Scan, the monitoring flexibility gained will increase your
Note: Remember to adjust the squelch threshold level before using Scan.
SCAN RESUME METHOD
Before using Scans, it’s necessary to decide under what condition you want your transceiver to
continue scanning after detecting and stopping for a signal. You can choose one of the following
modes. The default is Time-Operated mode.
Your transceiver stops scanning when detecting a signal, remains there for approximately 5
seconds, and then continues to scan even if the signal is still present.
Your transceiver stops scanning when detecting a signal and remains on the same frequency until
the signal drops out. There is a 2 seconds delay between signal drop-out and scan resumption to
allow time for any responding stations to begin transmitting.
Note: Pressing and holding [MONI] causes the transceiver to stop scanning; releasing [MONI]
causes it to resume scanning.
Selecting Scan Resume Method
1. Press [F] + [S] to enter Scan Menu mode.
2. Press [UP] or [DOWN] to select Time-Operated (TO), or Carrier-Operated (CO) mode.
3. Press any key other than [LAMP], [MONI], and [F] to exit Menu mode.
MEMORY CHANNEL SCAN
Memory Scan allows all memory channels containing data to be scanned.
1. Press [S].
Scan starts with the channel last recalled.
To reverse the scan direction, use [UP] (upward scan) or [DOWN] (downward scan).
2. To quit Memory Scan, press any key other than [LAMP], [MONI].
Note: The squelch must be closed for Scan to function.
Locking Out Memory Channels
Memory channels that you prefer not to monitor while scanning can be locked out.
1. Recall the desired memory channel.
2. Press [F],  to switch Lockout ON (or OFF).
A star appears below the memory channel number to indicate that the channel has been locked
CONTINOUS TONE CODED SQUELCH SYSTEM
You may sometimes want to hear calls from only specific persons. The Continuous Tone Coded
Squelch System (CTCSS) allows you to ignore (not hear) unwanted calls from other persons who are
using the same frequency. Simply select the same CTCSS tone as selected by the other persons in
your group. A CTCSS tone is sub audible and is selectable from among the 50 standard tone
Note: CTCSS does not cause your conversation to be private. It only relieves you of listening to
1. Select the desired channel number.
2. Press [F],  to switch the CTCSS function ON (or OFF).
“CT” appears when CTCSS is ON.
3. Press [F], .
The current CTCSS frequency appears.
4. Use [UP], [DOWN] to select a tone frequency.
5. Press any key other than [LAMP] and [MONI] to complete the setting.
This function prevents unauthorized individuals from changing the transceiver settings.
1. Press [F] (1 second) to switch the function ON (or OFF).
A key icon appears when the function is ON.
Battery Saver becomes active when the squelch is closed and no key is pressed for more than 10
seconds. This function becomes passive whenever the squelch is opened or any key is pressed.
1. Press [F] +  to switch the function ON (default) or OFF.
AUTOMATIC POWER OFF (APO)
Automatic Power Off is a background function that monitors whether any keys have been pressed, or
whether any control has been turned. After 1 hour passes with no operations, APO turns OFF the
power. However, 1 minute before the power turns OFF, “APO” blinks and a series of warning tones
1. Press [F] +  to switch the function ON or OFF (default).
Note: If the squelch opens or any settings are changed during the 1 hour period while APO is ON,
the timer resets. When the squelch closes or you stop changing the settings, the timer begins
counting again from 0.
You can illuminate the transceiver display by pressing [LAMP]. Approximately 5 seconds after
releasing [LAMP], the light goes OFF if no other key is pressed. Pressing any key other than [LAMP]
while the display is
lit restarts the 5 second timer; pressing [LAMP] turns OFF the light immediately.
To latch the light ON, press [F], [LAMP]. The light remains ON until you press [F], [LAMP] again.
The transceiver beeps each time you press a key on the keypad. You can also switch this function
1. Press [F] + , the menu appears, use [UP] or [DOWN] to switch the function ON (default) or
SWITCH MEMORY NAME/FREQUENCY DISPLAY
You can switch the display between memory channel and frequencies. You may sometimes want to
confirm frequencies stored in the memory channels.
1. Press [MR] to enter Memory Recall mode.
2. Press [MR] again to switch between memory channel and frequencies display.
Press [F] + , you may enter for the timer function.
KEYPAD DIRECT ENTRY
You can select the desired operating channel by entering digits directly from the keypad. Enter the next
digit within 10 seconds.
Memory Channel Number Entry
1. Press the numeric keys to enter a 2-digit memory channel number.
To recall channel 3, for example, enter “03”.
Operating temperature range -20
C to +55
Power supply requirement
110 x 50 x 30 mm.
Adjacent channel power 63dBm.
Max.diviation mod 2.5KHz/ UP 20dB
Hi: 5w. /Lo: 1w.
TX. Frequency response (Narrow band)
+1dB to -3dB of +6dB.Octave with
<0.25 µV at 12dB SINAD
Spurious response rejection
Audio frequency response (Narrow band)
+1dB to -3dB of +6dB.Octave with
300~3000Hz.For Reference DE/EMP
ADJUSTMENT INSTRUMENT LIST
Frequency Range: 0.1 ~ 300MHz
Output Level: 0.1uV ~ 50mV
Measuring Range: 1mV ~ 15V
Measuring Range: 0.1 ~ 20%
Frequency Range: 0.1 ~ 300MHz
±1ppm or Better
Sensitivity: 100mV or Better
Frequency Range: DC ~ 20MHz
Measuring Range: 0.01 ~ 15V
RF Power Meter
Measuring Range: 0.1 ~ 10W
Frequency Range: 1 ~ 300MHz
Stabilized Power Supply
Output Voltage: 0 ~ 15VDC
Output Current: 3A or more
Connection Type: 3.5
FM Modulation Analyzer Frequency Range: 20Hz ~ 5kHz
Measuring Range: 0 ~
Audio Signal Generator
Frequency Range: 20Hz ~ 5kHz
Output Level: 1mV ~ 1V
FREQUENCY TABLE (80 CHANNELS)
CH. FREQ. CH. FREQ. CH.
FREQ. CH. FREQ.
The receiver utilizes double conversion. The first IF is 44.545 MHz and the second IF is 455 kHz. The first
local oscillator signal is supplied from the PLL circuit. The PLL circuit in the transmitter generates the
2-1 Front End (RF AMP)
The signal coming from the antenna passes through the transmit/receive switching diode circuit, is amplified
by the RF amplifier (Q4), and passes through a BPF (L19). Then passes through the low-pass filters and goes
to the mixer.
2-2 First Mixer
The signal from the front end is mixed with the first local oscillator signal generated in the PLL circuit by
Q5 to produce a first IF frequency of 21.4 MHz. The resulting signal passes through the F1 MCF to cut the
adjacent spurious and provide the optimum characteristics, such as adjacent frequency selectivity.
2-3 IF Amplifier
The signal then passes through the first IF (Q6), and is amplified and goes to the IF IC (U2). U2 incorporates
the functions of the second OSC, second mixer, second IF amplifier, detector, noise amplifier, and noise
detector. The signal input to the IC is mixed with the RF signal of the second OSC to produce a 455 kHz
second IF signal. The signal is amplified by the IF amplifier. The signal passes through the ceramic filter
(F3) to provide the necessary selectivity. Finally, the IC (U2) and output as an AF signal detect the signal.
2-4 AF Amplifiers
The AF signal from the IF IC is amplified and decoded by IC (U2), and the signal passes through AF VOL
circuit and enters the audio power amplifier IC (U205) to drive the speaker.
Part of the AF signal from the IF IC enters the FM IC again, and the noise component is amplified and
rectified by a filter and an amplifier to produce a DC voltage corresponding to the noise level. The DC signal
from the FM IC goes to the analog port of the microprocessor (U3). U3 determines whether to output sounds
from the speaker by checking whether the input voltage is higher or lower than the preset value. To output
sounds from the speaker, U205 sends a high signal to the MUTE and turns U205 on though Q12, Q17.
2-6 Receive Signaling
300 Hz-and-higher audio frequencies of the signal output from the IF IC are cut by a low-filter (U5). The
resulting signal enters the microprocessor (U3). U3 determines whether the CTCSS matches the preset
value, and controls the MUTE and the speaker output sounds in line with the squelch results of that content.