Manuals+

Kenwood TM-401A UHF FM Transceiver

Instruction Manual

Introduction

You are the owner of the new TM-401A transceiver. Please read this instruction manual carefully before placing your transceiver in service. The unit has been carefully engineered and manufactured to rigid quality standards, and should give you satisfactory and dependable operation for many years.

Illustrated is the USA version.

Contents

1. Features

* European and British versions excluded.

2. Controls and Their Functions

Note: Illustrated is a version other than that of Europe/England.

Front Panel Controls

1. Tuning control (VFO):
Used to set frequency for transmission and reception. One step (depending upon VFO step) per one click shifts up and down. During memory recall operation, turning this control restores the operation to VFO with the frequency displayed. Note: One click rotation shifts the displayed frequency one step up or down. However, the frequency step may not be changed due to microcomputer transient.
2. POWER/VOL:
Power ON-OFF switch and volume control are combined. Turning the control fully counterclockwise will turn the power OFF. Clockwise rotation increases the volume.
3. SQUELCH:
The squelch control is used to eliminate noise during no-signal time. Normally, this control is adjusted clockwise until the noise disappears. For scan operation, this control must be set to the threshold point.
4. Keyboard:
  • MR/M1 (memory recall) key: Used to recall memory channel. When depressed, memory channel 1 is recalled. The MR indicator lights to show the memory recall is in operation. When recalling one of the memories in M2~M5, depress the MR/M1 key then the corresponding key of M2~M5.
  • MS/M2 (memory scan) key: Used to initiate scan for memory channels. During memory recall operation, depressing this key recalls memory CH2. During memory scan, depressing this key recalls the next memory channels.
  • MHz/M3 (1 MHz up) key: When depressed, the displayed frequency shifts up 1 MHz. During memory recall operation, depressing this key recalls memory CH3.
  • M/M4 (memory input) key: Used to store the desired frequency in memory channel (and in COM channel: European and British versions excluded). For memory input, refer to page 15. During memory recall operation, depressing this key recalls memory CH4. In memory CH4, transmit and receive frequencies are stored independently for odd split operation.
  • AL/M5 (alert) key: When depressed, the ALERT indicator lights to show alert operation is in progress. Depressing this key again releases this operation. For more details, refer to page 17. During memory recall operation, depressing this key recalls memory CH5. Memory channel 5 is used for odd split operation as for memory channel 4. The frequencies (transmit and receive) stored in CH5 designate frequency range limits for programmable scan operation. For more details, refer to page 15.
  • A/B (VFO A/B selection, scan stop) key: As shown in the table, this key provides three types of operation.
    ModeA/B key functions
    VFOEach time the key is depressed, VFO A and B are selected alternately.
    MRWhen depressed, VFO before memory recalled is restored.
    SCANWhen depressed, scan is released.
5. MIC connector (8 pin):
Microphone audio input. Frequency UP/DWN control and PTT lines are included. Pin assignments of the MIC connector are shown below.

FRONT VIEW

Note: Do not apply voltage to pins 2, 3, and 4. The pin 5 should not be shorted nor applied any voltage.

  • Pin 1: 5+8V (10 mA Load)
  • Pin 2: STBY (PTT)
  • Pin 3: MIC
  • Pin 4: UP
  • Pin 5: DWN
  • Pin 6: NC
  • Pin 7: GND (MIC)
  • Pin 8: GND
6. COM (common channel) key:
For users other than Europe and England. When the key is depressed, the common channel can be recalled any time. This channel can be changed to your desired frequency. For common channel replacement, refer to page 15. To release common channel operation, depress this key. No other key can release the operation. When the optional TU-3 tone unit is installed, the 1st tone frequency is emitted when operating the COM channel.
TONE switch (For British version):
When this switch is pressed, the repeater control tone burst signal (1,750 Hz) is emitted for about 0.5 seconds at the beginning of each transmission.
TONE switch (For European version):
When this switch is pressed, the repeater control tone signal (1,750 Hz) circuit is activated and the unit is set in the transmit mode.

Rear Panel Controls

9. REV switch:
Used to reverse the repeater shift to monitor a signal coming to a repeater. Setting this switch to ON in simplex operation locks the displayed frequency regardless of VFO, keyboard, and COM* CH operations. * European and British versions excluded.
10. TX OFFSET switch:
Used to set transmit frequency shifted from the displayed receive frequency when transmitting. For operation other than that of a repeater, place this switch to the "S" position. This equalizes the transmit frequency with the receive frequency. '+' setting shifts +5 MHz; '-' setting shifts -5 MHz from the receive frequency when transmitting. For European and British versions, refer to the table at the left. This operation is only effective in VFO and MR (M1~M3) operations. If a shift frequency goes beyond the operating frequency range when depressing the PTT switch to transmit, a beep will sound three times to indicate the misoperation. However, transmit frequency is emitted in simplex mode. *With the optional TU-3 tone unit installed, either '+' or '-' setting of the TX OFFSET switch interconnects the TU-3 2nd tone frequency setting. (* European and British versions excluded.)
11. ANT connector lead:
Connect a 50-ohm antenna to this terminal.
12. DC Power Terminal:
DC power input terminal. Connect the supplied power cord with plug. Input voltage is 13.8 V DC. Observe plus (+) and minus (-) polarity!
13. SP Terminal:
Connect the supplied 8 ohm speaker to this jack.

Right Side Panel Controls

14. Remote jack:
Used to connect the optional FC-10 unit, controlling the operation frequency.

Front Panel Indicators

7. HI/LOW switch:
HI setting: This setting allows the transmitter to transmit power output up to 12 watts. LOW setting: This setting allows the transmitter to transmit power output approx. 1 watts.
8. Display:
  • a. Frequency display: During VFO A or B, frequency, for example, 435.025 (445.025 for USA) is displayed in four digits as "5.025". During MR (M1~M5) operation, frequency, for example, 435.250 (445.250 for USA) is displayed in four digits as "5.250". During COM* operation, frequency is displayed in four digits. At this time, zero at the last digit is half size. * European and British versions excluded.
  • b. Scan indicator: During scan operation, this dot flashes.
  • c. VFO B indicator: In operation other than scan, this dot lights to show MHz. Lights when VFO B is in operation.
  • d. MR indicator: Lights during memory recall operation (M1~M5, MS).
  • e. ALERT indicator: Lights during alert operation.
  • f. ON AIR indicator: Lights when transmitting.
  • g. BUSY indicator: Lights during reception with squelch opened. This can be used to see if the channel is busy or not.
  • h. S & RF meter: Indicates the incoming signal strength by LEDs during reception. During transmission, LEDs light to show the RF output level strength. With the HI/LOW switch HI, all LEDs light. With the HI/LOW switch LOW, two to four LEDs light.

3. Installations and Connections

Antenna

The performance of the transceiver depends upon the type of antenna to be used. To ensure the maximum performance of the TM-401A, select a suitable antenna and adjust it for low VSWR.

Various types of antennas for UHF mobile operation are available.

Note: For gutter-mount installation, the antenna bracket must be grounded to the car body as shown below. Affix the antenna securely, referring to the antenna instruction.

Antenna Installation Diagram Description: Shows various antenna mounting locations on a vehicle: Roof-top system, Roof side system, Front fender, Trunk lid system. It also illustrates routing the coaxial cable through the rear window, door fitting, or trim plate to the transceiver.

Mobile Installation

Interconnection: The TM-401A is equipped with a speaker.

Installation location: Using the supplied mounting bracket, install the transceiver under the dashboard or on the side of the console in your car as shown. If your car is equipped with an electronic fuel injector, the transceiver should be as far from the control equipment as possible. The transceiver should be located away from your knees.

Installation procedure:

  1. Secure the bosses on each side with 4 flat head screws.
  2. Affix the cushion (C) on each side of the mounting bracket.
  3. Secure the mounting bracket to a car chassis as shown. When installing the bracket, be sure the front part of the bracket faces you.
  4. Insert the transceiver so the bosses on the transceiver slide into the grooves of the mounting bracket.
  5. To stack with the TM-201A (2 m), first secure the supplied stack plate to the TM-401A with bosses, then stack the TM-201A. Second, insert the stacked transceivers so the bosses on the upper transceiver slide into the grooves of the mounting bracket.

Note: Be sure to use flat washers. Otherwise, installation to the mounting bracket is not done well. However, when stack installation with the TM-201A is attempted, do not use these washers since the stack plates are used.

Diagram Descriptions:

  • Fig. a Boss securing: Shows securing bosses with flat head screws and flat washers.
  • Fig. b Cushion attachment: Illustrates affixing cushions (B and C) to the mounting bracket.
  • Fig. c Mounting bracket installation: Depicts mounting the bracket to a surface using flange nuts, flat washers, spring washers, and hex. head bolts.
  • Fig. d Transceiver installation: Shows how to slide the transceiver onto the mounting bracket using its bosses. Also shows stacking with another unit using a stacking plate.

Communications Speaker Installation

Note: To keep driving safe, do not install the speaker to the ceiling.

Diagram Descriptions: Illustrates several examples (1-2, 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8) of how to mount the speaker using brackets, cushions, tapping screws, and nuts onto various surfaces in a vehicle, such as seats or dashboards.

Power supply

Connect the supplied power cable with fuse directly to the battery terminals. Connecting to the cigarette lighter socket can cause a poor connection, and excessive voltage drop.

Diagram Description: Shows the TM-401A connected to a car battery via a fuse and power cable, with a rubber grommet for firewall entry.

Ignition noise

The transceiver is designed to suppress ignition noise; however, if excessive noise is present, it may be necessary to use suppressor spark plugs (with resistors). For this purpose, the TRIO-KENWOOD PG-3A is available.

Fixed Station Installation [general]

Power supply: A regulated DC power supply (13.8 V DC, 3.8 A or more) is required. It is recommended that the TRIO-KENWOOD PS-430 be used for a power supply. NOTE: Preferably, voltage should be adjusted to 13.8 V DC. Current capacity is more than 3.8 A. The regulated supply should be equipped with a built-in protection circuit for both overcurrent and overvoltage. CAUTION: A battery charging power supply cannot be used.

Antenna: Various types of fixed station antennas are commercially available, select your desired antenna according to your installation space and application. Note that the SWR of your antenna should be less than 1.5:1. A high SWR will cause the TM-401A protective circuit to operate, reducing the transmit output power. Transceiver performance depends largely on the type of antenna used. For fixed station operation there are ground plane antennas (omnidirectional) and Yagi antennas (unidirectional). The Yagi antenna is suitable for long distance operation (DX) or communication with a specific party. The ground plane antenna is generally used for local operation.

Diagram Descriptions:

  • Shows a typical fixed station setup with a Yagi antenna on a tower and a ground plane antenna.
  • Illustrates connecting the TM-401A to a PS-430 power supply.

4. Operation

Reception

When power and antenna connections are complete, set the controls and switches as follows:

Diagram Description: Shows the front panel of the TM-401A with numbered controls.

After verifying the initial setup of controls and switches, proceed as follows:

  1. Turn the POWER/VOL control to turn on power. The indicators on the display light to show the transceiver is operating.
  2. As the POWER/VOL control is turned clockwise, either noise or a QSO is heard.
  3. To eliminate the no-signal noise, use the SQUELCH control. For SQUELCH control operation, refer to next explanation.
  4. Tune to the desired frequency using MAIN DIAL.

SQUELCH control: To eliminate receiver noise at the no-signal condition, slowly adjust the squelch clockwise until the noise disappears and the BUSY indicator goes off (threshold point). When a signal is received, the squelch will open, the BUSY indicator will light and the speaker will operate. The SQUELCH control is also used for scan operation control. If the signal is weak or fades during mobile operation, readjust the squelch for constant reception.

Transmission

To transmit, first select frequency to be used and see whether it is busy or not. If it is not busy, simply depress the mic PTT switch for transmission. The ON AIR indicator lights.

Transmitter precautions:

  1. The TM-401A antenna impedance is 50 ohms. Be sure to use only an antenna of 50 ohms impedance.
  2. Check the intended transmit frequency before operating to prevent interference with other stations.
  3. Pressing the microphone PTT switch places the transceiver in transmit mode; the ON AIR indicator will light and the LED bar meter shows transmitter power. Recommended talk distance to the microphone is approximately 5 cm.

HI/LOW power switch: QSO in locals can be enjoyed with less interference to others and with less power consumption by reducing the RF output power. This is accomplished by depressing the HI/LOW switch, which reduces power from 12 W to approx. 1 W. Power indication will drop to approximately "2~4" on the meter.

16 key AUTO PATCH OPERATION (For U.S.A. version only)

To operate, hold the mic PTT switch depressed until keys are started operating.

Note:

  1. When the tone encoder is started operating, the transceiver is in transmit mode even with the PTT switch released.
  2. More than about 0.8 seconds keying interval restores the transmit mode to receive mode.
  3. The touch-tone encoder level can be readjusted according to your requirement. When readjusting, set the deviation to 3 kHz by the mic built-in VR with both the 3 and 6 keys of the encoder held depressed. Next, hold both the 2 and 3 keys depressed to verify the deviation which is within 1.2 kHz ±0.3 kHz.

VERIFICATION BEEP TONE

When operating, the beep sounds to indicate operation. Beep level can be adjusted by the potentiometer inside. (page 18)

BeepWhen beep will sound
OnceWhen key operated correctly.
TwiceWhen CH1 is busy during alert operation.
Three timesWhen ordering memory scan with all memory channels empty. When an offset frequency is out of operating frequency range.
Four times repeatedlyWhen transmit frequency for odd split is not stored, the beep will sound until the frequency is stored.
Five timesDuring REVerse operation.
Eight timesWhen memory is ready to be stored.
Once for approx. 1.5 sec.When memory is stored.

MEMORY INPUT IN (REPEATER COM CHANNEL AND*) MEMORY CHANNEL

(1) In memory channels 1 - 3 (Simplex channels)

ProcedureOperation
1 Freq. settingSet frequency to be stored using the tuning control or mic UP or DWN switch.
2 Memory standbyDepress the M/M4 key. The beep will sound eight times.
3 Memory inputDepress M1, M2 or M3 key while the beep is sounding. The 1.5 second beep sounds to verify the memory input.

(2) In memory channels 4, 5 and COM* (split channel)

ProcedureOperation
1 Receive freq. settingSet receive frequency to be stored using the tuning control or mic UP or DWN switch.
2 Memory standbyDepress the M/M4 key. The beep will sound eight times.
3 Memory inputDepress M4, M5 or COM* key while the beep sound is sounding. The 1.5 second beep sounds when the memory is input. Then the beep sounds 4 times repeatedly to require a transmit frequency input.
4 Transmit freq. settingSet transmit frequency to be stored using the tuning control, mic UP or DWN switch, or MHz key.
5 Memory input (transmit)Depress the same key used in step 3. The 1.5 second beep sounds when the memory is input.

* European and British versions excluded.

SCAN OPERATION

(1) Memory scan (Memory channels 1 - 5 are scanned.)

Before operating scan, adjust the SQUELCH control to eliminate the noise.

ProcedureOperationIndication
1 Scan startDepressing the MS key initiates scan from memory channel 1 to 5 as shown.Flashes
Empty channel is skipped. Scan will stop at busy station.
2 Quick scanDepressing the MS key recalls the next memory channel.
3 Scan releaseDepressing the A/B key or the mic PTT switch stops the scan. The displayed memory channel is restored to memory recall mode.Lights

To perform MS operation again, depress the A/B key to release MR operation.

(2) Programmable scan

During VFO A or B operation, depressing the mic UP or DWN switch initiates scan programmed within the range set between receive and transmit frequencies designated in memory channel 5. As shown in the figure, R denotes the receive frequency in CH 5; T denotes the transmit frequency in CH 5.

Diagram Description: Shows scan operation in VFO A and VFO B, illustrating up scan and down scan directions. Also notes that when R and T are equal, scan operates through the whole frequency range.

ProcedureOperationIndication
1 Scan range settingStore lower and upper limit frequencies in memory channel 5 by operating the M, M5, tuning control UP, DWN or MHz switch.Flashes
2 Scan startHold the mic UP or DWN switch depressed for more than one second. The scan starts. The dot starts flashing.
3The scan will stop at busy station and resume in 6 seconds.
4 Scan resumeScan resumes regardless of signal when operating the tuning control or UP/DWN switch.
5 Rapid scanHolding the UP/DWN switch depressed allows rapid up or down scan. Holding the MHz key depressed allows rapid scan in 1 MHz steps.
6 Scan directionDuring up scan, depressing the DWN key or turning the tuning control one click to the left reverses the direction. During down scan, reversing the above procedure reverses the direction.
7 Other scan range operationHolding the UP/DWN key depressed allows the scan to go beyond the upper or lower frequency limit. Example: During up scan from R to T, hold the UP key depressed and allow the scan to go beyond T. The scan goes from T to R.
8 Scan releaseDepressing the A/B key or mic PTT switch releases the scan. The flashing dot will stop.Lights

ALERT OPERATION

Used to monitor the frequency stored in memory channel 1, whether or not it is busy, during any mode operation. When memory channel 1 is busy, two beeps sound.

Diagram Description: Shows a timeline indicating monitoring every 6 seconds, with a 0.3-second beep during alert operation, during which key operation is inhibited.

When the ALERT operation is in use, memory channel 1 is monitored once every 6 seconds. During this period, voice is silenced. During alert operation for 0.3 seconds, note that key operation is inhibited.

5. Maintenance and Adjustment

COVER REMOVAL

1. Loosen 5 screws ($2.6 imes5$ mm) of the side panels.

2. To remove the top cover, remove 2 screws ($2.6$ x $5$ mm).

3. To remove the bottom cover, remove 5 screws ($2.6$ x $5$ mm).

Diagram Description: Shows the transceiver with arrows indicating screw locations for cover removal.

BEEPER ADJUSTMENT

Adjust VR1 on the B unit (X53-1350-11/61) to your listening preference.

Diagram Description: Shows a circuit board with VR1 highlighted.

LITHIUM BATTERY

A lithium battery is contained in the transceiver to retain memory. Therefore, turning off the POWER switch, disconnecting the power cable, or a power failure will not clear the memory. The battery will last approximately five years. When the battery discharges an erroneous display may appear on the LED. Lithium battery replacement should be performed by an authorized TRIO-KENWOOD service facility, either your TRIO-KENWOOD dealer, or the factory.

Note: When the lithium battery is replaced, the microprocessor must be reset.

MICROCOMPUTER RESET

Depress the reset switch with a nonconductive rod through the reset opening of the bottom cover as shown.

Diagram Description: Shows the bottom of the transceiver with a reset opening.

6. Accessories

USE OF THE REMOTE FREQUENCY CONTROL (OPTION)

Connecting the remote frequency control (FC-10) allows you to operate the transceiver more handily.

Note: When connecting or disconnecting the FC-10 from the transceiver, the POWER switch of the transceiver should be set to OFF, or the FC-10 may be damaged.

Diagram Description: Shows the FC-10 remote controller with numbered controls and indicators.

1. Display:

  • ① Frequency display: Indicates in four digits. Example: Indication 5.000 MHz denotes 445.0 MHz (435.0 MHz: other than USA).
  • ② ALERT display: During ALERT operation, the (★) lights.
  • ③ VFO A/B: (8) denotes VFO A; (6) denotes VFO B.
  • ④ Scan display: Flashes during scan operation. In memory scan, memory address is displayed at 3. In programmable scan, (R) or (b) is displayed at 3.
  • 5 MHz key: When used, the VFO displayed frequency is shifted up in 1 MHz steps.
  • 6 MR key: This key has two functions: Memory recall; and COM* recall.
  • 7 UP/DWN key: These keys function the same as those of the microphone.
  • 8 A/B key: This switch functions the same as that of the transceiver. With this switch, COM* operation can be released.

* European and British versions excluded.

PS-430 POWER SUPPLY

KPS-7 POWER SUPPLY (in USA only)

7. Block Diagram

For users other than Europe and England, refer to this diagram.

Diagram Description: This is a functional block diagram illustrating the internal architecture of the Kenwood TM-401A transceiver. It shows the main functional units: B Unit (X53-1350-11), Final Unit (X45-1340-11), A Unit (X44-1540-11), and Display Unit (X54-1740-01). These units are interconnected via various signal paths, including RF, control signals, audio, and power. Key functional blocks within these units include the VCO, PLL, mixers, amplifiers, filters, detectors, and control logic. The diagram also indicates connections for accessories like the microphone, remote controller, and an optional tone unit (TU-3).

8. Specifications

For users other than Europe and England, refer to this specifications.

[General]

[Transmitter]

[Receiver]

[Auto patch microphone (MC-48) supplied]

Note: Circuit and ratings are subject to change without notice due to developments in technology.

Manufacturer Information

A product of TRIO-KENWOOD CORPORATION, 17-5, 2-chome, shibuya, shibuya-ku Tokyo 150, Japan.

TRIO-KENWOOD COMMUNICATIONS, Compton, California, U.S.A.

TRIO-KENWOOD COMMUNICATIONS, GmbH, Steinbach TS, West Germany.

TRIO-KENWOOD ELECTRONICS, N.V., Zaventem, Belgium.

TRIO-KENWOOD (AUSTRALIA) PTY. LTD., Lane Cove N.S.W. 2066, Australia.

© 35305 PRINTED IN JAPAN B50-4060-00KMW (T)

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