Kenwood TM-441A User Manual

144MHz FM TRANSCEIVER

TM-241A/241E

430/440MHZ FM TRANSCEIVER

TM-441A/441E

1200MHz FM TRANSCEIVER

TM-541A/541E

INSTRUCTION MANUAL

KENWOOD CORPORATION

©PRINTED IN JAPAN B62-0031-00(T) 91/12 1110 9 8 7

Thank you for purchasing this new transceiver.

NOTE:

IMPORTANT:

Please read this instruction manual carefully before placing your transceiver in service.

SAVE THIS INSTRUCTION MANUAL.

CAUTION:

Long transmission or extended operation in the HI power mode might cause the rear of this transceiver to get warm. Do not place the transceiver where the heat sink (rear panel) might come in contact with plastic or vinyl surfaces.

This instruction Manual covers the following models. TM-241A:

TM-241E: TM-441A: TM-441A: TM-441E: TM-541A: TM-541E:

144MHz FM TRANSCEIVER

(U.S.A. and general markets)

144MHz FM TRANSCEIVER (U.K. and European markets) 440MHz FM TRANSCEIVER (U.S.A. only) 430MHz FM TRANSCEIVER (General markets) 430MHz FM TRANSCEIVER (U.K. and European markets)

1200MHz FM TRANSCEIVER (U.S.A. only)

1200MHz FM TRANSCEIVER (European markets)

If disregarded, inconvenience only, no risk of

equipment damage or personal injury.

CAUTION:

Equipment damage may occur, but not personal injury.

FCC WARNING This equipment generates or uses radio frequency

energy. Changes or modifications to this equipment may cause harmful interference unless the modifications are expressly approved in the instruction manual. The user could lose the authority to operate this equipment if an unauthorized change or modification is made.

CONTENTS

1. BEFORE OPERATION ..................................... 4

2. SPECIFICATIONS ............................................ 6

3. ACCESSORIES ................................................ 7

4. INSTALLATION INSTRUCTIONS

5. OPERATION CONTROL FUNCTIONS RECEIVER OPERATION

Reception ...................................................... 16

Frequency Selection ..................................... 17

Frequency Step Selection Programmable VFO Tuning Limits ALT(TM-541A/Eonly)

TRANSMITTER OPERATION

Time-out Timer (TOT) ................................... 20

MEMORY

Microprocessor Memory back-up

Initial State .................................................... 21

Microprocessor Initialization ......................... 21

Memory Channel Memory Contents Memory Entry Memory Channel Recall

Memory Shift ................................................. 24

SCAN

Scan Operation

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17 18 19 20

21 22 22

Hold/Resume Programming ......................... 25

Band Scan .................................................... 26

Programmable Band Scan

Memory Channel Scan ................................. 27

Memory Channel Lockout Priority Alert Function

REPEATER OPERATIONS

Transmitter Offsets Reverse Function

Tone Operation ............................................. 29

Tone Frequency Selection

Autopatch (U.S.A. version only) TONE / CTCSS OPERATION DTSS (Dual Tone Squelch System) OPERATION DRS (Digital Recording System)

OPERATION ................................................... 34

PAGING TONE ALERT SYSTEM

APO (Automatic Power Off) ............................ 48

DIM(Dimmer) .................................................. 48

BEEP............................................................... 49

LOCK/A.LOCK ................................................ 49

6. BLOCK DIAGRAM and SCHEMATIC DIAGRAM Another sheet

7. MAINTENANCE

IN CASE OF DIFFICULTY

8. OPTIONAL ACCESSORIES

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26 27

28 28

29 29

30 30

50 51

AWARNING BEFORE OPERATION

TO PREVENT ELECTRIC SHOCK, FIRE AND OTHER

INJURY. PLEASE NOTE THE FOLLOWINGS:

To avoid risk of electric shock,under no circumstances

Do not place this unit,where it will be exposed to direct sunlight or close to heating appliances.

To ensure good ventilation, do not put anything on top of the cabinet and allow at least 15 cm (6 inches) of space behind the unit.

The power requirement is 13.8 VDC. Never attempt connection to a 24 VDC source.

Do not place the unit in areas off excessive dust, high humidity or on unstable surfaces.

Do not drop pieces of metal, needles, coins and other

electrically conductive materials into the unit.

Do not touch the power plug, when your hands are wet.

Do not pull the power cord, when disconnecting it from the AC wall outlet. Grasp the plug and ensure that your fingers do not touch the live pins.

If an abnormal odor or smoke is detected, immediately turn the power off and pull out the power plug. Contact the KENWOOD service station or our dealer.

CLEANING

1. Turn the power off, before cleaning the unit.

2. Do not use any type of abrasive pad, thinner, benzine or any substances which may damage the unit.

3. Wipe the front panel and other exterior surfaces of the unit with a soft dry cloth or a soft cloth lightly moistened with water.

2 SPECIFICATIONS

TM-241A(U.S.A) TM-241A/E TM-441A(U.S.A) Frequency range MHz Mode Antenna impedance Operating temperature

Power requirements

Ground

Current drain Frequency stability

Dimensions (WXHXD) (mm) (Projections included)140 X 40 X 160(5-1/2” X1-37/64"X6-19/64") ( 140 X 40 X172(5-1/2"X1-37/64"X6-25/32") Weight (kg) 1.2(2.65lbs)

Output power *

Modulation

Spurious radiation

Maximum frequency deviation

Audio distortion (at 60% modulation) Less than 3% (300 to 3000 Hz)

Microphone impedance

Circuity

Intermediate frequency lst/2nd

Sensitivity (12dBSINAD)

Selectivity

Squelch sensitivity Less than 0.1 jzV

Output (5% distortion)

External speaker impedance 80

'Jotes

2.* Recommended duty cycle :1 minute; Transmit,3 minutes Reception

Transmit mode Receiver mode

HI 50W 35W

MID Approx low

LOW Approx. 5W

144 to 148 144 to 146

Less than llA

10.7MHz / 455kHz

—6dB: More than 12 kHz —60dB Less than 24 kHz

438 to 450 430 to 440 430 to 440

-20°Cto +60”C (-4°Fto +140°F)

13.8V DC±15%(11.7~15SV)

Less than 0.6A

Less than ±10 ppm

Reactance modulation

Less than — 60 dB

Double conversion superheterodyne

Less than 0.16 //V

More than 2 W across 8 0 loads

TM441A

F3E(FM)

50Q

Negative

Less than lOA

Approx low

Approx. 5W

±5KHz

6000

30.825MHz / 455kHz

Less than 0.177 jaV

TM441E TM-541A/E

1240 to 1300

Less than 6A

Less than±3ppm

low

59.7MHz/455kHz

Less than 0.1 juV

3 ACCESSORIES

Unpack your new transceiver carefully, and examine it for visible damage If the equipment has been damaged in shipment, notify the transportation company immediately. Save the boxes and packing material for future shipping. The following accessories should be included in the box with the transceiver.

DTMF Microphone (U.S.A. CANADA only) or Dynamic Microphone (GENERAL market only) or Dynamic Microphone (EUROPE market only) Microphone Hook (U.S.A. CANADA only) Mobile Mounting Kit

Bracket Screw set Self tapping Screw (U.S.A. CANADA only) ... N46-3010-46 2 ea.

Hex wrench Stacking plate (TM-441A/441E/541A/541E).. J21-4147-14 2 ea.

DC power Cable

Fuse (TM-241A/241E: 15A).. F05-1531-05 1 ea.

(TM-441A/441E: lOA).. F05-1031-05 1 ea. (TM-541A/541E: 8A) ... F05-8021-05 1 ea.

Instruction Manual ....................... B62-0031-XX 1 copy

Warranty Card ..................................................... 1 ea.

(U.S.A., CANADA , EUROPE market s only)

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T91-0380-X5 1 ea.

T91-0379-X5 1 ea.

T91-0382-X5 1 ea. J20-0319-24 1 ea. J29-0436-03 1 ea.

N99-0331-05 1 ea.

WOl-0414-041 ea.

E30-2111-05 1 ea.

4 INSTALLATION INSTRUCTIONS

4-1 INSTALLATION Mounting Bracket

When installing the transceiver in a vehicle consider the

ease of operation and safety when selecting the

location for the mounting bracket.

1. Install the bracket using the supplied flat washers and self tapping screws ( 4 pcs.each).

2. Attach the transceiver loosely using the 4 SEMS screws.

3. Align the grooves in the bracket with the transceiver’s screws ( Fig. A) and slide the transceiver to the rear.

4. Adjust the viewing angle in the bracket to the desired position ( Fig. B).

5. Hold the transceiver in place and tighten the 4 SEMS screws using the supplied wrench.

4-2 CONNECTION 4-2-1 Mobile Installations

Cautions :

1. Before installing the power cable, be sure to remove the negative lead from the battery for safety.

2. After installation and wiring, be sure to double check for correct installation before reconnecting the negative lead to the battery terminal.

3. If the fuse opens, be sure to check that each conductor has not been damaged by short circuiting, etc. Then replace with a new fuse of the same rating.

4. After completing the wiring, wrap the fuse holder with heat resistant tape to protect against heat and moisture.

5. Do not remove the fuse even if the power cable is too long.

A. Battery Connections

Connect the power cable directly to the battery terminals. Using of the cigarette lighter socket will lead to a poor connection, and will result in poor performance. Pay close attention to the polarity of the cables when connecting them to the battery.

Make sure the positive (+) and negative (—) lead polarity is correct w/hen connecting to the battery.

Engine compartment-

Fuse

Select a location where the power cable is pro tected from heat, mois

Battery

If the wiring hole in the fire wall or chassis is too small, disas semble the fuse holder to thread the wire through the hole.

ture or abrasion when securing the cable.

Passenger compartment

^ Make sure the cable does

Chassis or fire wall

From passenger compartment

(№===

Thread like this

To the

, transceiver

not directiv contact the e^ of the hole by usir>g a grommet.

B. Ignition Noise

This transceiver has been designed to suppress ignition noise; however, if excessive noise is present, it may be necessary to use suppressor spark plugs (with resistors).

4-2-2 Fixed Station

4-2-3 Antenna

A regulated DC power supply (13.8 VDC capable of supplying at least 11 Amperes) is required. The PS-430 or the PS-50 are recommended.

1. Never connect the AC power cable to the AC outlet until all other connections have been made.

2. Before connecting and disconnecting the power connector, be sure to turn OFF the POWER switches of both the transceiver and the DC power supply.

3. Observe polarity of the DC power cable. The transceiver operates on 13.8 VDC, negative ground. Battery polarity must be correct. The power cable is color coded :

Red + (Positive polarity) Black -> — (Negative polarity)

The type of antenna that is used will greatly affect the

performance of the transceiver. Use a properly adjusted antenna, of good quality, to enable your transceiver to perform at its best. The antenna input impedance is 50

ohms. Use 50-ohm coaxial cable such as RG-8U or 8D-2V for this connection. If the antenna is far from the transceiver the use of low loss coaxial cable, such as RG-

8U is recommended. Match the impedance of the coaxial cable and that of the antenna so that the SWR is

less than 1.5 to 1. The protection circuit in the

transceiver will activate if the SWR is particularly poor

(greater than 3 to 1).

High SWR values will cause the transmitter output to

drop, and may lead to TVI or BCI reports.

Caution : We recommend that you install a high quality

lightening arrestor in your antenna lines for protection against fire,electric shock,personal

injury,or damage to the radio itself.

5 OPERATION

511 CONTROL FUNCTIONS

AL CTCaS

‘188.8.8.8.8.5 f ss

TM-241A

(1) POWER switch

Press to turn the transceiver on or off. Press the VFO/M^V or MR/M key and switching the power on will reset the VFO or MEMORY, The microphone PF key can be programmed when the power is switched on.

(2) Tuning control

This control is used to select the desired transmitter/receiver frequency, MHz step, memory channel, frequency step, tone frequency, scan direction, etc.

(DVOL control

This control is used to adjust the volume from the internal and external speaker (if used). Clockwise rotation will increase the volume and counterclockwise rotation will decrease the volume.

(i)SQL (Squelch) control

This control is used to select the desired squelch threshold level.

(DLOW/DIM key

LOW This function is used to select the transmit output power level (HI, MID(Except TM-541A/E), or LOW). DIM This function is used to select the intensity of the front panel display illumination. (See page 48) Pressing the F key for longer than 1 second and then press the LOW/DIM key while the F indicator is flash ing will turn the time-out timer function on and off.

(§) Microphone connector

Attach the supplied microphone to this connector. The pin out of the connector is shown in the accompanying illustration.

® GND (Microphone audio!

, ® RX Audio Output

(Approx 100 mV/10 k ohm)

(D 8 VDC (Max 150 mA)

®VFO/M^V key

This key is used to return to VFO operation after

operating in the MR or CALL channel mode. Pressing this key will allow the tuning control and microphone UP/DWN keys to increase or decrease

the operating frequency.

Press and hold the key for longer than 1 second to initiate VFO scan. Pressing the key after scan has been initiated will cause scan to stop.

Pressing the key within 10 seconds of pressing the F key will copy the memory channel or call channel data to the VFO. This allows you to change parameters of that channel without actually changing the data that has been stored in memory.

Pressing the F key for longer than 1 second and then pressing the VFO key will cause radio to toggle the hold / resume mode between Time Operated scan

and Carrier Operated scan.

If you press and hold the VFO key while you turn on the POWER switch you will reset the

microprocessor’s VFO memory, without destroying the memory channel or call channel data.

(D MR/M key

This key is used to select MR (Memory Recall) mode from the VFO mode. The tuning control can then be used to select the desired Memory channel.

Pressing the key for longer than 1 second will initiate memory channel scanning.

Pressing the key within 10 seconds of pressing the F key will store the displayed data into memory. In the MR channel mode pressing the F key for longer than 1 second and then pressing the MR key

will cause the Memory channel to skip during

Memory channel scan mode. If you hold and press this key while you turn on the

POWER switch you will clear all the microprocessor’s operator programmed memory section.

(DMHz/LOCK key

This key is used to tell the microprocessor that you

wish to increase or decrease the operating frequency in 1 MFIz increments.

Pressing this key within 10 seconds of pressing the F

key will cause the key lock function to activate, protecting the currently displayed data from accidental erasure.

Pressing the F key for longer than 1 second and then pressing MHz/LOCK key while the F indicator is flashing will turn the AUTOMATIC POWER OFF function on or off.(See page 48)

frequency a beep will sound from the speaker.

Pressing the same key sequence again will cancel

the function.

Pressing the F key for longer than 1 second and then pressing the SHIFT/AL key will store the currently displayed data as the upper limit for the program mable VFO tuning limit function.

Press this key to activate the call channel function.

Press the F key momentarily and then press the CALL key to store the currently displayed data into the CALL channel. The radio will allow you up to 10 seconds to press the CALL key after pressing the F

key.

Pressing the F key for longer than 1 second and then pressing the CALL key will store the currently displayed data as the lower limit for the programmable VFO tuning limit function. To operate the transceiver with the RC-10 press and hold the CALL key on the transceiver and then turn on the POWER switch.

(DSHIFT/AL key

SHIFT function

Pressing this key alone to select the desired transmitter offset direction. Pressing the key will cause the radio to shift from one offset direction to the next, i.e. “+” to " to simplex where no

indicator shows, (“—’’to“— —’’ for European

versions)

AL function

Pressing the F key momentarily and then pressing

the SHIFT/AL key will cause the radio to activate the

Priority Alert function. When this function is active

the radio will scan memory channel 1 at approxi

mately a 5 second interval. If there is activity on the

(DTONE/T.ALT key

TONE function

Pressing this key by itself causes the radio to select the desired tone signaling mode. When the “T’’ indicator is illuminated in the display the transceiver will transmit the selected subaudible tone. When the “CTCSS’’ indicator is illuminated the transceiver will both transmit the subaudible tone and will also

remain squelched until the proper subaudible tone

is received.

TONE frequency selection

Pressing the F key for longer than 1 second and then

pressing the TONE/T.ALT key will allow you to select the desired tone frequency. To change to a

different tone frequency rotate the tuning control

or press the UP/DWN switches on the microphone

until the desired tone frequency appears in the

display. To return to the normal frequency display

you can press any front panel key except the power

switch.

TONE ALERT function

If you press the F key momentarily and then press the TONE / T.ALT key, T.ALT function will be activated. This function will cause the radio to emit a series of beeps when an incoming signal is received. (See page 47)

'I88.8.8.B.8.S ififi

fJ« WP.

tc© °© ©°0

CTcsa ^

5-1-2 LCD Display Panel

(i)--(-A.LOCK

^-----

0—-DTSSir«-.

B8.8.8.8.8.sm8

(Z)REV/STEP key

This key is used to reverse the transmit / receive frequencies during repeater operation. If you have selected simplex this key will not function! Pressing the F key momentarily and then the REV/STEP key will allow you to select the desired VFO tuning step and Scan step size. Use the tuning control to select the desired tuning step and then press any front panel key except the POWER switch to return to the normal frequency display. Pressing the F key for longer than 1 second and then pressing the REV / STEP key will turn the BEEP function Off or ON.

(D DR/DT/ALT key(ALT: TM-541A/541E only)

DR/DT function

Pressing this key alone to select the DTSS(Dual Tone Squelch System) function or DRS (Digital Recording System) function.

ALT function

Pressing the F key momentarily and then the

DR/DT/ALT key will cause the ALT(Automatic Lock Tuning) function of the TM-541A/541E to activate.

Pressing the F key for longer than 1 second and then

pressing the DT/DR/ALT key will turn the DRS function ON or OFF.

(D LOCK

A.LOCK

DTSS DRS

APO

BUSY

® »afjifjilMfJii!

LOW MID

ON AIR

On when the Lock function has been activated. On when the All Lock function has been activated. On when the Automatic Lock Tun ing function is active. When the ALT system is operating the direction in dicator will turn on if the system shifts the receiver frequency. On when the DTSS function has been activated. On when the Digital Recording Sys tem is active. On when the Automatic Power Off function has been activated. On when the squelch opens. This level meter indicates the rela tive receiver signal strength or the

relative transmitter power output. Indicates the relative output power

setting for transmit. No indicator for high power. On when the Time Out Timer func

tion has been activated.

On during transmit.

® ★ ¿/¿/ Indicates the active memory channel

number. ★ indicates that the chan nel is locked out. C is displayed during call channel. Either PO, PI, P2, P3, or PA is displayed during paging.

® F I On whenever the F key has been de

pressed. Also shows the last memory channel number that had been se lected. On when the Tone Alert function is active. The indicator flashes when signal has been received.

@ CTCSS

____

REV

@ — + Display the selected transmitter off

On when the Tone Decode and En code function has been activated.

— On when the Tone Encode function

has been activated. On when the Priority Alert function

has been activated.

On when the Reverse function has

been activated. set direction.

Both — and + light at the same time during split channel operation.

@ :388.888s Displays the operating frequency to

the nearest kHz digit; or the tone frequency etc.

— The indicator flashes when scan

ning.

5-1-3 Rear Panel

Attach an antenna with a low SWR and an

impedance of 50 ohms.

Connect the supplied DC power cable to this

connector.

Pay close attention to the polarity. Red is positive and black is negative.

d)Fuse holder

Contains a requaired fuse. TM-241A: 15A, TM-441A: lOA, TM-541A: 8A Do not use a larger fuse as damage might result to the transceiver.

0 External speaker jack

This jack is used to connect an external speaker. The speaker should have an impedance of 8 ohms.

5-1-4 Microphone

(D ®

@ ®

@ p@ 0® 00

European version version

U.S.A.

dXDUP/DOWN switches

These switches can be used to increase or decrease the VFO frequency, the Memory channel number, and the Tone frequency, etc..

(D PTT (Push to Talk) switch

The transceiver will transmit whenever this switch is depressed. Scan operations may be canceled by press ing this switch without transmitting.

@CALL key (except European version)

This key functions just like the CALL key on the front

of the radio. 1750 key (European version) The transceiver will transmit with 1750 Hz repeater access tone whenever this switch is depressed.

(DVFO key

This key functions just like the VFO key on the front of the radio.

(D MR key

This key functions just like the MR key on the front of the radio.

(Z) PF (Programmable Function) key

This key can be programmed to perform any of the following functions: MHz key (Initial setting from the factory); or SHIFT-

key; or TONE key; or REV key;or DR/DT key ; or LOW key.

To program the key use the following procedure:

1. Turn the POWER switch on the transceiver OFF.

2. Press and hold the key on the front panel of the set that corresponds with the function you wish to program the microphone key to perform.

3. Turn on the POWER switch while the key on the front panel is held in.

4. Release the front panel key.

One additional function can be programmed that is

not included on the front panel of the transceiver.

This is known as the MONITOR function. This will al

low you to open squelch to check the band for a clear frequency. This will function even if you are operat ing in the CTCSS decode mode or DTSS mode or PAG

ING mode.

MONITOR programming

Press and hold the F key on the front panel as you turn on the POWER switch of the transceiver and then release the F key.

(D 16-Tone DTMF keypad (U.S.A. and CANADA version

only) These buttons are used to activate the DTMF encod er.

(D LOCK key

This key will deactivate all functions of the micro

phone except the PTT function and DTMF key pad.

5-2 RECEIVER OPERATIONS

Audio confirmation is provided whenever a front panel

key is depressed. You can disable this function by pressing the F key for longer than 1 second and then pressing the REV/STEP key.

5-2-1 Receptoin

1. Connect the power supply, antenna, and microphone and then adjust the controls as follows:

Power Switch

Vol Control ................... Full Counterclockwise

Power switch of power supply (Fixed station) SQL Control

2. Turn on the Power Supply and then turn on the transceivers POWER switch. The display should indicate a frequency. Fig.l shows examples of frequencies that will appear on the various models. In addition to the frequency you may see one or more control indicators illuminats on the display.

TM-241A/241E

ihHDDO

............

.................

TM-441A

(U.S.A. version)

TM441A/TM-441E

OFF

Full Counterclockwise

,,,, o o o n

HHu.u u u

^^nnnn

'^3u.u u u

TM-541A/541E

,,.,nnnn

id'iu.u u u

Note The frequencies shown above are the default frequencies after a microprocessor reset. If the display shows incomplete data or you think the displayed frequency is in error you should reset the Microprocessor. Memory Initialization on page 21.

3. Rotate the VOL control clockwise until a signal or noise is heard coming from the speaker.

4. Rotate the tuning control or press the microphone UP/DWN switches to select an open channel. Then rotate the SQL control clockwise until the noise just disappears and the BUSY indicator turns off. This point is known as the Squelch Threshold point. The squelch control must be adjusted to this setting for the Scan functions to operate properly.

5. Select the desired operating frequency using the microphone or tuning control. When a signal is received the S-meter will deflect and the BUSY indicator will turn ON.

Caution Turn off the transceivers POWER switch before you start or stop your vehicles engine, or your home power supply.

Fig. 1

5-2-2 Frequency Selection

5-2-3 Frequency Step Selection

You can change the dial frequency while in the VFO mode. The frequency can then also be stored in memory, or in the call channel using the techniques that will be described in this manual.

MR key

# VFO Mode Operation Frequency Selection

1. Press the VFO/M^V key to select the VFO mode.

2. Rotate the tuning control or press the microphone UP/DWN switches to select the desired frequency.

# Memory Channel Selection

1. Press the MR/M key.

2. Rotate the tuning control or press the microphone UP/DWN switches to select the desired memory

channel.

# CALL Channel Selection

Press the CALL key to select the Call channel.

The frequency step is indicated in the chart below. STFP

5i =^15^

TM-241A/E TM-441A/E TM-541A/E

To select the desired tuning or scan step size use the following procedure:

1. Press the VFO/M^V key to select the VFO mode.

2. Press the F key momentarily. The F indicator should light in the display.

3. Press the REV/STEP key within 10 seconds of pressing the F key. The current frequency step size will be displayed.

o o o o o o

o o o

±20t

o o o

n2.5?

o o

:^25

4. Rotate the tuning control or press the UP/DWN switches on the microphone until the desired tuning step size appears in the display.

5. To complete the programming of the step size you can press any key on the front panel except the

POWER key, or simply wait 10 seconds and the microprocessor will automatically return to the normal frequency display.

The chart below shows how the microprocessor will correct a new step size.

5,10,15,20 to 12.5,25

0,5,10,15 0 20,25,30,35 25 40,45,50,55 50

60,65,70,75,

80,85,90,95

12.5,25 to 5,10,15,20 0

12.5 25

37.5 30 50

62.5 75 70

87.5 80

0 10 20

50 60

5-2-4 Programmable VFO Tuning Limits

The TM-241/441/541 series radios provide the capabil ity of programming the VFO tuning range, in 1 MHz band segments, as well a providing a separate program mable band scan function(See page 26). For example you could tell the transceiver that you only wish to tune the 144 MHz and 145 MHz band segments. The tuning controls and microphone UP/DWN switches would then only tune within these specific frequency limits. The procedure for specifying these limits is described below.

1. Press the VFO/M^V key to select the VFO mode.

2. Rotate the tuning control or press the microphone UP / DWN switches until the desired lower tuning range appears in the frequency display. For example with the TM-241 you might want to select the 144 MHz band, and dial up 144.100 MHz.

3. Press the F key for longer than 1 second. The F indicator should begin flashing.

4. Press the CALL key within 10 seconds. A long beep will sound and the F indicator will turn off in the display. This indicates that the lower limit has been successfully stored in memory.

+ 41 hidden pages