Kenwood TM-231A User manual

COOMN=>
144MHz FM TRANSCEIVER
TM-231A/231E
220MHz FM TRANSCEIVER
440/430MHz FM TRANSCEIVER
A/431E
1200MHz FM TRANSCEIVER
TM-531A/531E
INSTRUCTION
MANUAL
KENWOOD CORPORATION

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:
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-231A : 144 MHz FM transceiver
(U.S.A. and general markets)
TM-231E : 144 MHz FM transceiver
(U.K. and European markets)
TM-331A : 220 MHz FM transceiver (U.S.A. only)
TM-431A : 430 MHz FM transceiver
(Genreral market)
TM-431A : 440 MHz FM transceiver (U.S.A. only)
TM-431E : 430 MHz FM transceiver
(U.K. and European markets)
TM-531A : 1200 MHz FM transceiver (U.S.A. only)
TM-531E : 1200 MHz FM transceiver
(European market}
The following explicit definitions apply in this manual:
Note : If disregarded, inconvenience only, no risk of
equipment damage or personal injury.
Caution =: Equipment damage may occur, but not per-
sonal injury.
CONTENTS
1. BEFORE OPERATION...........cc.cccssseesseee
2. SPECIFICATIONS and ACCESSORIES....
3. INSTALLATION INSTRUCTIONS ...........
4. OPERATION
OPERATING CONTROLG...........ccecceceenseeceees 9
RECEIVER OPERATION........scnessncvesenecerennes 15
Reception
Frequency Selection
Frequency Step Selection .....cccccccccseeseeees 16
Programabie VFO ........c.cccessessseeeenaeseneee 17
ALT as iscsnsoswonaaitcvanhcaececueeeeaseanenersteevsee 19
TRANSMITTER OPERATION ......ccccscceeeseseees 20
MEMOR ¥ .. Sassinubas pevkctnedeeeeedederenaaasats arene 21
Microprocessor Memory Back-up
Microprocessor Initialization
Memory Channel
Memory Contents
Memory Entry
Memory Recall
Memory Shift
SCAN 3 oss tieetced ooureds vaenizadewias ccs tana dee eeee 25
Scan Operation
Hold/Resume Programming
Band Scan
Programmable Band Scan.......sseeceeseseeeees 26
Memory Channel! Scan
Memory Channel Lockout

Priority Alert FUNCTION .......cceceecaeeeeeeereees 27
REPEATER OPERATION ......sccccecereeceesccereees 28
Transmitter Offsets
Reverse Function
Tone and CTCSS Operation
Autopatch Operation
TONE ALERT SYSTEM......ccrseeeceness
DIGITAL RECORDING SYSTEM
Tone Quality Level Selection
Maximum Recording Phrase Selection
RECOrdING wavecc caedineseewewsweevecdrednvdedsasesess 33
Play {Back wesdscenesviectadeti heaton ate das eteey see 34
Automatic Recording
BLOCK DIAGRAM and
SCHEMATIC DIAGRAM............... another sheet
MAINTENANCE ..........:::ccceeee ese eeeeneeeenenteres 35
In Case of Difficulty ........cscsscescnsreeeeeeeeee 36
OPTIONAL ACCESSORIES
CTCSS unit TSU-6 0... cccceceeneeerseeeeneeeees 37
Digital Recording Unit DRU-1
Remote Controller RC-10
1.[a.warning] BEFORE OPERATION
TO PREVENT ELECTRIC SHOCK, FIRE AND OTHER INJU-
RY. 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.
24 VDC source.
Do not place the unit in areas of excessive dust, high hu-
midity or on unstable surfaces.
Do not drop pieces of metal, needles, coins and other elec-
trically conductive materials into the unit.
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 your 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 AND ACCESSORIES
2-1. SPECIFICATIONS
Models TM-431A
Specifications TM-231A TM-231E TM-331A (U.S.A. versk )/TM-431A/431E TM-531A TM-531E
Frequency range [MHz] | 144 t0 148 | 144 to 146 | 220 to 225 | 438 to 450 | 430 to 440 | 1240 to 1300
Mode F3E (FM)
Antenna impedance 500
Power requirements 13.8 VOC +15% (11.7 to 15.8)
Ground Negative
Frequency stability Less than +10 ppm Less than +3 ppm
Current | Transmit mode Less than 11 A Less than 6.5 Al Less than 9.5A Less than 5.5 A
drain Receiver mode with no signal Less than 0.6 A
Operating temperature — 20 °C to +60 °C (-4 °F to +140 °F}
Dimensions (WxHxD) [mm] 140 x 40x 160 (5-1/2” x 1-37/64” x 6-19/64")
(Projection included) (141 x 42x 171 (5-9/16" x 1-21/32” x 6-47/64"})
Weight {kg] 1.2 (2.65 Ibs)
HI 50 W } 25 W 35 Ww 10W
Output | MID 10 W 10 W 10 Ww =
power” | LOW Approx. 5 W Approx. 5 W Approx. 5 W TW
Modulation Reactance modulation
Spurious radiation Less than — 60 dB Less than -50 dB
Maximum frequency deviation +5 kHz
Audio distortion (at 60% modulation) Less than 3% (300 to 3000 Hz)
Microphone impedance 500 to 600 0
Circuitry Double conversion superheterodyne
Intermediate frequency 1st/2nd 10.7 MHz/455 kHz 30.825 MHz/455 kHz 59.7 MH2/455 kHz
Sensitivity (12 dB SINAD} Less than 0.16 4V
Selec- -6 dB ___More than 12 kHz
tivity -60 dB Less than 24 kHz Less than 36 kHz
Squetch sensitivity Less than 0.1 pV
Output (5% distortion) More than 2 W across 8 0 loads
External speaker impedance 8a
Lt
od
Pe]
=
E
@
c
s
=
=
Receiver
Notes:
1. Circuit and ratings are subject to change without notice due to advancements in technology.
2. * Recommended duty cycle: 1 minute Transmit, 3 minutes Reception.

2-2. ACCESSORIES
Unpack your new transceiver carefully and examine it for
visible damage. If the equipment has been damaged in ship-
ment, notify the transportation company immediately. Save
the boxes and packing material for future shipping.
The following accessories should have been included in the
box with the transceiver.
MC-44DM DTMF Microphone
(US CAL CORIY) is siete es peceeinitaeccendeciiins T91-0380-X5....... 1 ea.
or
Dynamic Microphone ..........:ccceeeecneeeeee T91-0379-X5....... 1 ea.
or
Dynamic Microphone (European version}..T91-0382-X5....... 1 ea.
Microphone Hook (U.S.A. only).........008 J20-0319-24 ....... 1 ea.
Self Tapping Screw (U.S.A. only)...... N46-3010-46....... 2 ea.
Mobile Mounting Kit (1 ea.)
Bracket .00......ceceeceeseeene eee eereeeren teen ee J29-0436-03 ....... 1 ea.
Mounting SCrewS........c. ce eceeeeneeeeeens N99-0331-05....... 1 ea.
SEMS -Scraw vsessctesdccecshacnat eeenters
Self Tapping Screw s
Flat Washer i. ccasscicapeceesesatecnteareenss
Stacking Plate
(TM-331A/431A/431E/531A/531E)..J21-4147-14
DC Power Cable... cei ccecceereceneees E30-2111-05...
TM-431A/431E: 10A ..FO5-1031-05
TM-331A/TM-531A/S31E: 8A... FO5-8021-05
Instruction Manual........ccccsesceceeeseeeeeeee B50-8286-XX....1 copy
Warranty Card (U.S.A. version, European version) ........... 1 ea
3. INSTALLATION INSTRUCTIONS
3-1. INSTALLATION
Mounting Bracket
When installing the transceiver in your vehicle consider the
ease of operation and safety when selecting the location
for the mounting bracket.
1. Install the bracket using the flat washers and self tap-
ping screws that were supplied with the transceiver. (4
Pieces ea.)
2. Attach the transceiver loosely using the 4 SEMS screws
that were supplied.
3. Align the grooves in the bracket with the transceivers
screws (Fig. A) and slide the transceiver to the rear.
4. Adjust the viewing angle of the bracket to the desired
position. (Fig. B)
5. Hold the transceiver in place and tighten the 4 SEMS
screws, using the wrench that was supplied.
a)
+B
Fig. A

3-2. CONNECTION
3-2-1. Mobile Installations
Cautions:
1.
Before
installing
the
power
cable
disconnect
the
nega-
tive
lead
from
the
battery
for
safety.
2. After installation and wiring have been completed go
back and check your work to ensure that you have not
made any errors, before you reconnect the negative bat-
tery lead.
3.
If
the
fuse
opens
be
sure
to
check
that
each
conductor
is
undamaged,
then
replace
the
fuse
with
one
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.
Use
of
the
cigarette
lighter
socket
will
lead
to
a
poor
con-
nection,
and
will
result
in
poor
performance.
Play
close
at-
tention
to
the
polarity
of
the
cables
when
connecting
them
to
the
battery.
Remember
Red
is
positive
and
black
is
nega-
tive
!
Make sure the positive (+) and negative (—) lead polarity is correct
when connecting to the battery.
aa Engine compartment ~— }—+ Passenger compartment
: Fuse
(i =5)
To the
transceiver
t
Chassis or
fire walt
B 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.
From passenger
compartment
Thread like this
B. Ignition Noise
This transceiver has been designed to suppress ignition
noise, however, you may occasionally encounter an instal-
lation where the use of suppressor type plugs might be called
for.
3-2-2. Fixed Station
A
regulated
DC
power
Supply
(13.8
VDC)
is
required.
The
PS-430 or the PS-50 are recommended.
CAUTION:
1.
Never
connect
the
AC
power
cable
of
the
Power
supply
to
the
AC
outlet
until
all
other
connections
have
been
made.

2. Before connecting and disconnecting the power connec-
tor be sure to turn OFF the POWER switch on the front
panei of the transceiver and the power supply.
3. Observe proper polarities when connecting the DC power
cable to the supply.
Remember red is positive and black is negative.
3-2-3. Antenna
The type of antenna that is used will greatly affect the per-
formance of the transceiver. Use a properly adjusted anten-
na, 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 con-
nection. If the antenna is far from the transceiver the use
of low loss cable is recommended. Match the impedance
of the coaxial cable and that of the antenna so that the SWR
will be less than 1.5 to 1. The protection circuit in the tran-
sceiver will activate if the SWR is particularly poor (greater
than 3 to 1). High SWR values will cause the transmitter
output to fall off and may lead to TVI or BCI reports.
CAUTION:
We recommend that you install a high quality lightening ar-
restor in your antenna lines for protection against fire, elec-
tric shock, personal injury, or damage to the radio itself.

4. OPERATION
4-1. CONTROL FUNCTIONS
@) POWER switch
Press to turn the transceiver ON or OFF.
@ Tuning control
This control is used to select the desired transmit-
ter/receiver frequency, MHz step, Memory Channel, Fre-
quency Step, Tone Frequency, Scan Direction, etc.
@) VOL control
This control is used to adjust the volume from the inter-
nal and external speaker (if used). Clockwise rotation will
increase the volume and counterclockwise rotation will
decrease the volume.
@) SQL (Squeich) 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 pow-
er level (Hi, MID, or LOW). Note the TM-531A/531E does
not have a MID position.
DIM
This function is used to select the intensity of the front
panel display illumination. It is used in conjunction with
the F key, i.e. press the F key and then the LOW/DIM
key to alternate between High and Low display inten-
sities.
Microphone connector
Attach the supplied microphone to this connector. The
pin out of the connector is described in the accompany-
ing illustration.
GND @ GND (Microphone audio)
@ MIC
(Microphone Audio)
RX Audio Output
@
PTT
{Approx
100
mV/10
k.ohm)
(Push
to
Talk)
@ DWN
@ up
@® 8 VDC (Max 150 mA)

®
10
LOCK - - REV + AL ORS cTCSsS x)
(ge8B88s: +88 |
VFO key
This key is used to return to VFO operation after operat-
ing in the MR or CALL channel mode. Pressing this switch
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 initi-
ate VFO scan. Pressing the key after scan has been in-
itiated 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 chan-
nel 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 Car-
rier 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 key
This key is used to select MR (Memory Recall) mode from
the VFO mode. The tuning contro! 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 POW-
ER switch you will clear all the microprocessor’s, opera-
tor programmed, memory section.
@ MHz 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.

@ 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.
Press the F key for jonger than one second so that the
F indicator begins to flash. Then press the CALL key to
enter the lower limit for the programmable VFO tuning
limit function. If you wait longer than 10 seconds to press
the CALL key after the F begins flashing the microproces-
sor will assume that you pressed the key in error and can-
cel the function. You will have to start over again if the
F indicator turns off.
To operate the transceiver with the RC-10 press and hold
the CALL key on the transceiver and then turn on the
POWER switch.
C= SHIFTAL TONET.ALTREVSTEP DRS
® 2)
@ SHIFT/AL key
SHIFT funciion
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 other, ie. “’ + "
to “‘—’’ to simplex where no indicator shows. (’’—"’ to
‘*_ _** for TM-431E European versions)
AL function
Pressing the F key momentarily and then pressing the
SHIFT/AL key will cause the radio to activate the Priori-
ty Alert function. When this function is active the radio
will scan the contents of memory channel 1 at approxi-
mately 5 second intervals. If there is activity on the fre-
quency 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 dis-
played cata as the upper limit for the programmable VFO
tuning limit function.
@ TONE/T.ALT key
Pressing this key by itself causes the radio to select the
desired tone signalling 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 subau-
dible tone and will also remain squelched until the proper
subaudibie tone is received.
If you press the F key momentarily and then press the
TONE/T.ALT key the T.ALT function will be activated.
This function will cause the radio to emit a series of beeps
when an incoming signal is received that will open the
squelch. The function will work with or without the
CTCSS option installed.
11

TONE frequency selection
Pressing the F key for longer than one second and then
pressing the TONE/T.ALT key will allow you to select the
desired tone frequency. The display will indicate the cur-
rent Tone frequency. To change to a different tone fre-
quency rotate the tuning control or press the UP/DWN
switches on the microphone until the desired tone fre-
quency appears in the display. To return to the normal!
frequency display you can press any front panel key ex-
cept the power switch.
SHIFTAL TONET.ALTREVSTEP DRS
@
12
|
@ ®
REV/STEP key
This key is used to reverse the transmit/receive frequen-
cies during repeater operations. If you have selected sim-
plex 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 fre-
quency 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.
@ DRS/ALT (ALT: TM-531A/531E only)
This key is used to turn the Digital Recording System off
or on. Please see page 31 for additional information on
this optional accessory.
Pressing the F key momentarily and then the DRS/ALT
key will cause the ALT function of the TM-531A/531E
to activate.

LCD DISPLAY PANEL
RIOTS)
@ LOCK On when the LOCK function has been ac-
tivated.
@- + Displays the selected transmitter offset
== direction.
(European version)
@REV Qn when the Reverse function has been
activated.
@AL On when the Priority Alert function has
been activated.
®DRS Gn when the Digital Recording System is
active.
@®ctTcss On when the Tone Decode function is
t active.
On when the Tone Encode function is
active.
@ <acoD> On when the Auto Lock Tuning function
is active. When the ALT system is oper-
ating direction the direction indicator will
turn on if the system shifts the receiver
frequency.
g On when the Tone Alert function is active.
The indicator flashes when an incoming
signal has opened the squelch.
@ Displays the operating frequency to the
188 88a Gs nearest kHz digit; the frequency step size;
or the tone frequency.
fom The indicator flashes when scanning.
@ (Gusyl On when the squelch opens.
® eocmmmmm This level meter indicates the relative
receiver signal strength or the -relative
transmitter power output.
ar Ee ™~"1"1On whenever the F key has been
| | depressed. Also shows the last memory
L — — _.— J channel number that had been selected.
ro ~~ 1 The * indicator is on whenever the dis-
| * | played memory channel will be skipped
__ during memory scan operations.
GD) On during transmit.
ONATR
LOWMID Indicates the relative output power setting
for transmit. No indicator indicates full
power.
13

Rear Panel
@ ANTENNA connector
Attach an antenna with a low SWR and 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 one of the following fuse. Do not use a larger
fuse as damage might result to the transceiver.
TM-231A/231E:15A
TM-431A/431E: 10A
TM-331A/TM-531A/531E : 8A
@ External speaker jack
This jack is used to connect an external speaker. The
speaker should have an impedance of 8 ohms.
14
Microphone @ ©
U.S.A.
European version version
@ @ UP/DWN 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 cancelled 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 ac-
cess 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 function just like the MR key on the front of the
radio.
@) PF (Programmable Function) key
This key can be programmed to perform any of the fol-
lowing functions:
Mtz key (Initial setting from the factory); or SHIFT key;
or TONE key; or REV key; or DRS 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 pane! of the transceiver. This is
known as the MONITOR function. This will allow you to
open squelch to check the band for a clear frequency.
This will function even if you are operating in the CTCSS
decode 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. version only)
These buttons are used to activate the DTMF encoder.
See 4-6-4. for further information on their use.
@) LOCK switch
This key will deactivate all functions of the microphone
except the PTT function and DTMF key pad.
4-2. 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.
4-2-1. RECEPTION
1. Connect the power supply, antenna, and microphone and
then adjust the controls as follows:
Power Switch OFF
Vol Control Full Counterclockwise
Power switch of power supply OFF
(Fixed station)
SQL Control Full Counterclockwise
TM-431A
TM-231A/231E
(U.S.A.
version}
TM-531A/531E
(om tC ¥ | |
ert. - oe so 3-6 a a ena
TM-431A/TM-431E
Fig. 1
2. Turn on the Power Supply and then turn on the tran-
sceivers 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 fre-
quency you may see one or more control indicator turn
on in the display.
15

Note:
The frequencies shown above are the default frequencies
after a microprocessor reset. If the display shows incom-
plete data or you think the displayed frequency is in error
you should reset the microprocessor using the instructions
provided in 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 ro-
tate the SQL control clockwise until the noise just dis-
appears and the BUSY indicator turns off. This point is
known as the Squeich Threshold point. The squelch con-
trol must be adjusted to this setting for the Scan func-
tions to operate properly.
5. Select the desired operating frequency using the micro-
phone 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 you vehicles engine, or home power supply.
4-2-2. Frequency Selection
You can change the dial frequency while in the VFO made.
The frequency can then be also be stored in memory, or in
the call channel using the techniques that will be described
in this manual.
VFO mode
MR key VFO key VFO key CALL key
Z CALL key
MEMORY channel mode CALL channel mode i
MR key
@ VFO Mode Operation Frequency Selection
. Press the VFO 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
. Press the MR key.
2. Rotate the tuning contro! 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.
4-2-3. Frequency Step Selection
The frequency step is indicated in the chart below.
5 + 10 4 15 — 20 + 125 25
TM-231A/231E | O ° ro) ° ° ro)
TM-331A ° ° oO ° ro) O
TM-431A/431E | O ° oO oO ro) oO
TM-531A/531E | NAO NA O O ° |

To select the desired tuning or scan step size use the fol-
lowing procedure:
1. Press the VFO 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 dis-
played.
4. Rotate the tuning control or press the UP/DWN switches
on the microphone until the desired tuning step size ap-
pears 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 cor-
rect a new step size.
5, 10, 15, 20 to 12.5, 25 12, 5, 25 to 5, 10, 15, 20
0, 5 “9 0 0
10, 18 12.5 10
20, 25 25 25 20
aa = 37.5 30
50, 55 ne as
60, 65 :
70,
75
75
75
70
80, 85 87.5 80
90, 95 |
4-2-4. Programmable VFO tuning limits
The TM-231 series radios provide the capability of program-
ming the VFO tuning range, in 1 MHz band segments, as
well a providing a separate programmable band scan func-
tion (See section 4-5). For example you could tell the tran-
sceiver that you only wish to tune the 144.000 MHz and
145.000 MHz band segment by specifying any frequency
with these two segments. The tuning controls, microphone
UP/DWN switches would then only tune within these specif-
ic bands. The procedure for specifying the bands is described
below.
1. Press the VFO key to select ee
the VFO mode. oO
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-431 you might want to
select the 432.000 MHz
band, and dial up
432.560 MHz.
3. Press the F key for longer
than 1 second. The F indi- 42 3 6.
cator should begin flashing. aa
17

4.
Press the CALL key within
10 seconds. A long beep
will sound and the F indica-
tor will turn off in the dis-
play. This indicates that the
lower limit has been suc-
cessfully stored in memory.
. Now select the desired
upper tuning limit using
the MHz key and tuning
control, or microphone
UP/DWN switches.
With our example TM-431
we want the upper band
limit to be in the 435 MHz
band, and therefore dial up
435.560 MHz.
. Press the F key for longer
than 1 second. The F indi-
cator will again begin
flashing.
. Press the SHIFT/AL key wi-
thin 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
successfully stored in
memory.
For longer than 1 second
Flashing
SHIFTAL
8. To confirm that the
programming was properly
performed rotate the tuning
control or press the * 3 sed
UP/DWN switches. The ;
transceiver should not go YJ 69 8 Hy
above or below the
programmed band limits.
9. To clear both programmed
limits simultaneously you
should initialize the VFO
memory using the proce- re) |
dures discussed on page
10. You can reprogram
either limit independently
by following the appropri-
ate instructions above.
Nota:
An
internal
heterodyne
tone
resulting
from
internal
mixing
may be encountered near by 1244.150 MHz.
(TM-531A/531E only}

4-2-5. ALT (TM-531A/531E only)
The ALT system operates similar to an AFC (Automatic Fre-
quency Control) system. This system is useful when the fre-
quency 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.
(Example)
Frequency
Transmit Frequency Receive Frequency
of the Distant Station
ALT System is
performed.
Ca
Frequency
Transmit Frequency Receive Frequency
of the Distant Station
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.
To activate the ALT function
1. Press the F key momentar-
ily. The F indicator will turn
on in the display.
. While the F indicator is on
press the DRS/ALT key.
The ALT indicator will turn
on and the receiver will au-
tomatically center itself on
the incoming signal.
. To release the ALT func-
tion press the F key
momentarily and then the
DRS/ALT key.
Turns on when the transmit
frequency of the distant sta-
tion is higher than your receive
frequency.
Turns on when the transmit
frequency of the distant sta-
tion is lower than your receive
frequency.
19

4-3. TRANSMITTER OPERATION
Cautions:
1. Ensure that an antenna with a low standing wave ratio
(SWR) is attached to the antenna connector before at-
tempting to transmit. Failure to provide proper termina-
tion 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 possi-
ble, to avoid interfering with other stations.
Transmit
1. Select the desired operating frequency using any of the
methods previously discussed.
2. Check the frequency to see if it is occupied before you
transmit.
3. Press the PTT switch. The ON AIR indicator will light,
and the RF meter will deflect to the right.
Note:
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 swing full scale.
4. Speak into the microphone. The recommended distance
to the microphone is 5 cm (2 inches).
Note:
Talking closer may result in overdeviation of your trans-
mit signal, which might be reported as a loss of clarity
or of an excessively wide transmit signal. Talking too far
away may result in reports of weak audio.
20
5. Release the PTT switch to return to the receive made.
The ON AIR indicator should go out, and the RF meter
will return to zero.
4-4. MEMORY OPERATIONS
4-4-1. Microprocessor Memory back-up
A lithium battery is contained in this transceiver to retain
memory. Turning OFF the POWER switch, disconnecting the
power cable or an intermittent power failure will not erase
the memories. The battery life is estimated at 5 years. When
the battery has been exhausted erroneous information might
appear in the display.
Lithium battery replacement should be performed by an
authorized KENWOOD service facility, or your authorized
KENWOOD dealer. This equipment contains CMOS circuitry
and can be damaged by improper replacement procedures.
4-4-2. Microprocessor Initialization
The
initial
state
of
the
microprocessor,
as
delivered
from
the
factory is shown in the following chart.