Kenwood TM-241A User manual

GOOMNA»
144MHz FM TRANSCEIVER
TM-241A/241E
430/440MHz FM TRANSCEIVER
TM-441A/441E
1200MHz FM TRANSCEIVER
TM-541A/541E
INSTRUCTION MANUAL
KENWOOD CORPORATION
62-0031-00(T)

Thank you for purchasing this new transceiver.
IMPORTANT:
Please read this instruction manual carefully
before placing your transceiver in service.
SAVE THIS INSTRUCTION MANUAL.
CAUTION:
NOTE:
If
disregarded,
inconvenience
only,
no
risk
of
equipment
damage
or
personal
injury.
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.
Equipment
damage
may
occur,
but
not
personal
injury.
This instruction Manual covers the following models.
TM-241A: 144MHz FM TRANSCEIVER
(U.S.A. and general markets)
TM-241E: 144MHz FM TRANSCEIVER
(U.K. and European markets)
TM-441A: 440MHz FM TRANSCEIVER
(U.S.A. only)
TM-441A: 430MHz FM TRANSCEIVER
(General markets)
TM-441E: 430MHz FM TRANSCEIVER
(U.K. and European markets)
TM-541A: 1200MHz FM TRANSCEIVER
(U.S.A. only)
TM-541E: 1200MHz FM TRANSCEIVER
(European markets)
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
Ls
Ch PON
BEFORE:OPERATION | s..2c00 e064 820 ees 4
SPECIFIGATIONS 22tecicae spacers > 6
ACCESSORIES (20a) tien 3 7
INSTALLATION INSTRUCTIONS ...... ¥
OPERATION
CONTROL FUNCTIONS. 2 ......00000 a0. 10
RECEIVER OPERATION
Reception! © ....2. lot eer aT JEON 16
Frequency Selection ................... 17
Frequency Step Selection .............. 17
Programmable VFO Tuning Limits ...... 18
ALT(TM-541A/E only)...........-.-0-.- 19
TRANSMITTER OPERATION.............- 20
Time-out Timer'CFOT)) cc oceccen esses 20
MEMORY
Microprocessor Memory back-up ....... 21
[ittialiState oon. cee pis os So asa Oars 21
Microprocessor Initialization ........... 21,
Memory'Channél) 22:8. .60.. 62. c.eeces- 21
Memory Contents 2... 2.0 e..s.e3 bbe. ees 22
Memory Entfy) ). .2:0: .- cee sates S38. oes 22
Memory Channel Recall ............... 24
Memory SINE ya. cna sic eae bees kee 24
SCAN
ScaniOperation «is cscu cewsiesuwun aes 25
6.
Hold/Resume Programming ........... 25
Band Scatin’ 3o3. 2s Scdenes seems snares 26
Programmable Band Scan ............. 26
Memory ChannelScan ................ 27
Memory Channel Lockout ............. 27
Priority Alert Function .........60. e000 28
REPEATER OPERATIONS
Transmitter Offsets ................... 28
Reverse Function 29
Tone Operation 29
Tone Frequency Selection ............. 29
Autopatch (U.S.A. version only) ........ 30
TONE / CTCSS OPERATION.......... 30
DTSS (Dual Tone Squelch System)
OPERATION esnadeiccn arsine et annie: 31
DRS (Digital Recording System)
OPERATION. fin. ate ce see es bah ges ak 34
PAGING Xi. 5. hun. etter pase nes 41
TONE AEERT, SYSTEM... dcccccew ess. 47
APO (Automatic Power Off) ... 48
DIM@Diramer): ee sc uss 3 se asx 05.2 208 < 48
BEEP IMs $09 [er mos 49
LOCK/MILOCK! Men a5 a BAA 49
BLOCK DIAGRAM and
SCHEMATIC DIAGRAM Another sheet

A WARNING) BEFORE OPERATION
TO PREVENT ELECTRIC SHOCK, FIRE AND OTHER
INJURY. PLEASE NOTE THE FOLLOWINGS:
To avoid risk of electric shock,under no circumstances
should the unit be opened.
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
Ee
(a8
Turn the power off, before cleaning the unit.
Do not use any type of abrasive pad, thinner,
benzine or any substances which may damage the
unit.
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(USA) | TM-241A/E |TM-441A(US.A)| TM-441A TM441E TM541A/E
Frequency range MHz 144 to 148 | 144 to 146| 438 to 450 430 to 440 | 430 to 440 | 1240 to 1300
Mode F3E(FM)
Antenna impedance 500
Operating temperature —20°C to +60 (—4F to +1407)
‘s | Power requirements 13.8V DC +15%(117~158V)
S Ground Negative
S Cc t drai Transmit mode Less than 11A Less than 10A Less than 6A
urrent drain :
Receiver mode Less than 0.6A
Frequency stability Less than +10 ppm Less than 3ppm
Dimensions (WXHXD) (mm) (Projections included) 14040 x 160(5-1/2” X1-37/64"X6-19/64") (140 X40 X172(5-1/2"X 1-37/64"X6-25/32”)
Weight (kg) 1.2(2.65lbs)
HI 50wW 35W 10W
Output power * MID Approx 10W Approx 10W i
5 LOW Approx. 5W Approx. 5W 1w
_ Modulation Reactance modulation
2 | Spurious radiation Less than — 60 dB
£ Maximum frequency deviation E5KHz
Audio distortion (at 60% modulation) Less than 3% (300 to 3000 Hz)
Microphone impedance 6000,
Circuity Double conversion superheterodyne
Intermediate frequency 1st/2nd 10.7MHz / 455kHz 30.825MHz / 455kHz _59.7MHz/455kHz
S Sensitivity (12 dB SINAD) Less than 0.16 «V
'S | Selectivity —6dB: More than 12 kHz —60dB_ Less than 24 kHz
ce | Squelch sensitivity Less than 0.1 nV Less than 0.177 nV Less than 0.1 uV
Output (5% distortion) More than 2 W across 8 Q, loads
External speaker impedance 80
otes : 1.Circuit and ratings are subject to change without notice due to advancement in technology.
2.* Recommended duty cycle :1 minute: Transmit,3 minutes Reception

3 ACCESSORIES 4 INSTALLATION INSTRUCTIONS
Unpack your new transceiver carefully, and examine it
for visible. pes If ets pra ie has been 4-1 INSTALLATION
damaged in shipment, notify the transportation 7
company immediately. Save the boxes and packing Mounting Bracket
material for future shipping. When installing the transceiver in a vehicle consider the
The following accessories should be included in the box ease of operation and safety when selecting the
with the transceiver. location for the mounting bracket.
DTMF Microphone 1. Install the bracket using the supplied flat washers
(U.S.A. CANADA only) ......... T91-0380-X5 1 ea. and self tapping screws ( 4 pcs.each).
or E " 2. Attach the transceiver loosely using the 4 SEMS
Dynamic Microphone screws.
ENE market only) ......- T91-0379-X5 1 ea. 3. Align the grooves in the bracket with the
a Microphone transceiver’s screws ( Fig. A) and slide the transceiver
(EUROPE market only) ........ T91-0382-X5 1 ea. totherear, :
Microphone Hook 4. Adjust the viewing angle in the bracket to the
(U.S.A. CANADA only) ........ J20-0319-24 1 ea. desired position ( Fig. B). ;
Mobile Mounting Kit 5. Hold the transceiver in place and tighten the 4 SEMS
BYACKEES 51. ~ ave. oterare nia sieve J29-0436-03 1 ea. screws using the supplied wrench.
SCROW'SOE coca. morele e onstese N99-0331-05 1 ea.
Self tapping Screw
(U.S.A. CANADA only) ... N46-3010-46 2 ea.
Hexwrench: ...26c00sece08ce0s W01-0414-041 ea.
Stacking plate
(TM-441A/441E/541A/541E).. J21-4147-14 2 ea.
DC power Cable ............. E30-2111-05 1 ea.
Fuse (TM-241A/241E: 15A).. FO5-1531-05 1 ea.
(TM-441A/441E: 10A).. FO5-1031-05 1 ea.
(TM-541A/541E: 8A)... FO5-8021-05 1 ea.
Instruction Manual ........... B62-0031-XX 1 copy
Weartany (Cad... ais 2 sii ves won oxen sce 1 ea.
(U.S.A., CANADA , EUROPE market s only)

4-2 CONNECTION
4-2-1 Mobile Installations
Cautions : Make sure the positive (+) and negative (—) lead polarity is correct
1. Before installing the power cable, be sure to wvizen iconnecdngiiesthicibatteny
remove the negative lead from the battery for Pete Gore er Passengeneoinnartnent
safety. To the
2. After installation and wiring, be sure to double transceiver
check for correct installation before reconnecting
the negative lead to the battery terminal. Moke sure acti one
3. If the fuse opens, be sure to check that each Battery ‘ "when sian of ie hele by ua
Chassis or
conductor has not been damaged by short >
fire wall
circuiting,
etc.
Then
replace
with
a
new
fuse
of
If
the
wiring
hole
in
the
fire
wall
or
chassis
is
too
small,
disas-
the
same rating.
semble the
fuse
holder
to thread the
wire through
the
hole.
4.
After
completing
the
wiring,
wrap the
fuse
holder
From
passenger
with
heat resistant
tape to
protect
against
heat
oe
and
moisture.
Thread
like
this
.
Do
not
remove
the fuse
even
if
the
power
cable
is
too
long.
ao
A. Battery Connections
Connect the power cable directly to the battery B. Ignition Noise
terminals. Using of the cigarette lighter socket will lead : ; . Late 3
to
a
poor
connection,
and
will
result
in
poor
This
transceiver
has
been
designed
to
suppress
ignition
performance. Pay close attention to the polarity of the "0ise; however, if excessive noise is present, it may be
cables
when
connecting
them
to
the
battery.
necessary
to
use
suppressor
spark
plugs
(with
resistors).

4-2-2 Fixed Station
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.
. 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)
nN
4-2-3 Antenna
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
5-1-1 CONTROL FUNCTIONS
- - REV =
miesBBBBs a0
ae
AL cToss
@ POWER switch
Press to turn the transceiver on or off.
Press the VFO/MPV 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.
@Tuning control
This control is used to select the desired
transmitter /receiver frequency, MHz step, memory
channel, frequency step, tone frequency, scan
direction, etc.
@VOL 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.
@®SQL (Squelch) control
This control is used to select the desired squelch
threshold level.
©LOW/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
@
GND
(Microphone
audio)
D
MIC
(Microphone
Audio).
ery
®
RX
Audio
Output
@
pir
(Approx
100
mV/10
k
ohm)
(Push
to
Talk)
@
DWN
@ up
@® 8 VDC (Max 150 mA)

Te CCAT |
oe Se lake
SEORSECESCES)
@VFO/MPV 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.
@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.
@ MHz/LOCK key
This key is used to tell the microprocessor that you
wish to increase or decrease the operating
frequency in 1 MHz 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)

@CALL key
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.
© SHIFT/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
12
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.
© TONE/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)

@ 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.
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.
5-1-2 LCD Display Panel
oo eta a
@ LOCK
A.LOCK
@ <Eea>
@® Low mip
ORT)
° Ea
AES S 8 ®
5 ,
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.
13

Indicates the active memory channel
number. * indicates that the chan-
nel is locked out.
C is displayed during call channel.
Either PO, P1, P2, P3, or PA is dis-
played during paging.
On whenever the F key has been de-
pressed. Also shows the last memory
channel number that had been se-
lected.
xe) Q On when the Tone Alert function is
active. The indicator flashes when
signal has been received.
@CTCSS On when the Tone Decode and En-
{ code function has been activated.
On when the Tone Encode function
has been activated.
®, 8G
eF |
@® AL On when the Priority Alert function
has been activated.
4) REV On when the Reverse function has
been activated.
Q- + Display the selected transmitter off-
set direction.
Both — and + light at the same
@ time during split channel operation.
! Displays the operating frequency to
888885 the nearest kHz digit; or the tone
frequency etc.
The indicator flashes when scan-
ning.
5-1-3. Rear Panel
ES
Os
—
:
x
eee
@ ANTENNA connector
Attach an antenna with a
impedance of 50 ohms.
@ 13.8 VDC power input connector
Connect the supplied DC power cable to this
connector.
Pay close attention to the polarity. Red is positive and
black is negative.
@ Fuse holder
Contains a requaired fuse.
TM-241A: 15A, TM-441A: 10A, TM-541A: 8A
Do not use a larger fuse as damage might result to
the transceiver.
@ External speaker jack
This jack is used to connect an external speaker. The
speaker should have an impedance of 8 ohms.
e
low SWR and an

5-1-4 Microphone
=1om)
® © ©9 @@ © ©® 0®
att
Gam!
European version
@@UP/DOWN switches
These switches can be used to increase or decrease
the VFO frequency, the Memory channel number,
and the Tone frequency, etc..
@ 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.
®VFO key
This key functions just like the VFO key on the front
of the radio.
© MR key
This key functions just like the MR key on the front of
the radio.
U.S.A.
version
@ 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.
16-Tone DTMF keypad (U.S.A. and CANADA version
only)
These buttons are used to activate the DTMF encod-
er.
@LOCK key
This key will deactivate all functions of the micro-
phone except the PTT function and DTMF key pad.
15

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:
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.
Power Switch .. 2 OFF
Vol Control Full Counterclockwise
Power switch of power supply
(Fixed station) . 2, “OFF
SQL Control... ...+ Full Counterclockwise
Turn on the Power Supply and then turn on the
transceivers POWER switch. The display should
indicate a frequency. Fig.1 shows examples of
frequencies that will appear on the various models.
In addition to the frequency you may see one or
more control indicators Viupanats on the display.
TM-241A/241E (U.S.A. version) TM-' -541A/541E
44008
| 8008 298008
TM441A/TM-441E
Rotate the VOL control clockwise until a signal or
noise is heard coming from the speaker.
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.
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.

5-2-2. Frequency 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.
VFO mode
VFO key MR key
VFO key CALL key
CALL key
MEMORY channel mode CALL channel mode
MR key
VFO Mode Operation Frequency Selection
Press the VFO/MPV key to select the VFO mode.
Rotate the tuning control or press the microphone
UP/DWN switches to select the desired frequency.
Memory Channel Selection
Press the MR/M key.
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.
Nr@ Pre
5-2-3. Frequency Step Selection
The frequency step is indicated in the chart below.
STEP
§210215220212.5225
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OOO
T™-441A/E
|
O
CO
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O O
O
TM-541A/E
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eh
als
Sd
SD
el
To select the desired tuning or scan step size use the
following procedure:
1. Press the VFO/MP 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.

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 12.5,25 to 5,10,15,20
0,5,10,15 0 0 0
20,25,30,35 25 125 10
40,45,50,55 50 25 20
60,65, 70,75, 375 30
80,85,90,95
75
50 50
62.5 60
75 70
87.5 80
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.
. Press the VFO/MP 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.
Press the key for longer than
1 second.

5. Now select the desired upper tuning limit using the
N
9:
. Press the F key for longer than 1 second.
MHz key and tuning control, or microphone UP/DWN
switches.
With our example TM-241 we want the upper band
limit to be in the 145 MHz band, and therefore dial
up 145.100 MHz.
The F
indicator will again begin flashing.
. Press the SHIFT/AL key within 10 seconds. A long
beep will sound and the F indicator will turn off in
the display. This indicates that the upper limit has
been stored in memory.
1 second.
To confirm that the programming was _ properly
performed rotate the tuning control or press the
UP/DWN switches. The transceiver should not go
above or below the programmed band limits.
To clear both programmed limits simultaneously you
should initialize the VFO memory using the
procedures discussed on page 21. You can reprogram
either limit independently by following the
appropriate instructions above.
5-2-5 ALT (TM-541A/541E only)
The ALT system operates similar to an AFC (Automatic
Frequency Control) system. This system is useful when
the frequency of either station starts to drift. When this
occurs distortion of the signal is the usual result. The
ALT system will detect the drift and shift the frequency
to compensate.
To activate the ALT function
1. Press the F key momentarily. The F indicator will turn
on in the display.
2. While the F indicator is on press the DR/DT/ALT key.
The ALT indicator will turn on and the receiver will
automatically center itself on the incoming signal.
<ai>
Turns on when the transmit
frequency of the distant
station is lower than your
receive frequency.
Turns on when the transmit
frequency of the distant
station is higher than your
receive frequency.
Note:
The frequency display will not actually change, even though the
receive frequency might shift in order to properly tune the
incoming signal. When the ALT system is operating the Direction
indicator in the display will turn on to signal a change in the
receiver frequency. The direction indicator will show you if the
incoming signal was higher or lower than the displayed frequency.
3.To release the ALT function press the F key
momentarily and then the DR/DT/ALT key.
19

5-3. TRANSMITTER OPERATION
Caution
1. Ensure that an antenna with a low standing wave
ratio (SWR) is attached to the antenna connector
before attempting to transmit. Failure to provide
proper termination may result in damage to the
final amplifier section.
2. Always check to ensure the frequency is clear
before transmitting.
Note
The use of LOW power is recommended whenever
possible, to avoid interfering with other stations.
5-3-1 Transmit Basics
1. Select the desired operating frequency using any of
the methods previously discussed.
2. Press the LOW/DIM key to select the desired transmit
output.
20
3. Check the frequency to see if it is occupied before
you transmit.
4. Press the PTT switch. The ON AIR indicator will light,
and the RF meter will deflect to the right.
If you have selected the LOW power position, the low
indicator will appear in the display and the RF meter
will only deflect slightly. When HI power has been
selected the RF meter will deflect full scale.
5. Speak into the microphone. The recommended
distance to the microphone is 5 cm (2 inches).
5-3-2 Time-out Timer (TOT)
The TOT can limit the continuous transmission time to
30 minutes.
1. Press the F key for longer than 1 second, then press
the LOW/DIM key. The T indicator will light. To cancel
Press the key for longer than
1 second.
. When the time-out timer reaches the transmission
time limit, a beep will sound and the transceiver will
return to the receive mode. To transmit again,
release the PTT switch and press it again.
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