Kenwood TM-721A User manual

GOO/MNA»
144/440MHz FM DUAL BANDER
IM-721A
144/430MHz FM DUAL BANDER
IM-721A
TM-721E
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 piace the transceiver where the heat sink (rear
panel) might come in contact with plastic or vinyl surfaces.
The following explicit definitions apply in this manual:
Note 2 If disregarded, inconvenience only, no risk of
equipment damage or personal injury.
Caution : Equipment damage may occur, but not per-
sonal injury.
illustrations show the TM-721A.

CONTENTS
PWN>
INSTALLATION INSTRUCTIONS ..............00008
OPERATION.........:ccccccecnsccescncsarectsaseceascees
OPERATING CONTROLS
RECEIVER OPERATION. ..ccsccccescacccesscusccensces
Reception
Frequency Selection ....ccccccsreccssenccnvecscccae
Frequency Step Selection........ccccsssncceeesace
A.B.C. (Automatic Band Change) .......sesssees
Beep Tone
TRANSMITTER OPERATION ......ccccccssactecceees
REPEATER OPERATION ......cccessesecccsscccesecees
Transmitter Offsets
Reverse Function
Tone Operation
Autopatch (U.S.A. version only) ..cccsseoesseeoes
MEMORY .....ccccecscctecsccuccscuvesscevorseeeentscces
Microprocessor Memory Back-up
Microprocessor Initialization
Memory Channel
Memory Contents
Memory Entry .....cccscsecesccunnsscenccerscceueres
Simplex/Normal SHIFT
Qdd Split Channel
Call Channel.......cecccccsecccsestsecsscernacses
Memory Recall
Memory Shift
Scan Options
Programmable Band Scan/Band Scan
Memory Channel Scan
Hold Resume Programming
Priority Alert .......scccececesceseccrscentcsvercenses 27
Memory Channel Lockout
BLOCK DIAGRAM
and SCHEMATIC DIAGRAM 77°77" another sheet
MAINTENANCE ...........00.0cecsnsecsseccsceressensens 28
In Case of Difficulty ..........cccecescsscesesseeneneeee 29
OPTIONAL ACCESSORIES.............0:c+ececceceas 31
CTCSS unit TSU-6 (U.S.A. version) .....cccsenseees 33
REMOTE CONTROLLER RC-10.........0sesenccseeee 34
REFERENCE .............ccscesceeseecccscvcvccecnsvrscres 37

1. BEFORE OPERATION
Safety precautions The power requirement is 13.8 VDC.
Never remove the case unless instructed to do so in this In- Never attempt connection to a 24 VDC source.
struction Manual. If the internal parts are touched acciden-
tally, a serious electric shock might occur.
Never touch internal parts.
DC Power Supply:
Touching the power plug when your hands are wet may
result in a serious electric shock.
. _ . ~\Gnv”
If a metal object, such as a hair pin or a needle, comes into na \
contact with the power socket on the rear panel, a oT. Never touch with wet hands.
dangerous electric shock may result. Never permit children | ON
to put anything, especially metal objects, inside this unit.
DC Power Supply:
Never pull, bend or extend the power cord. This could
damage the power cord, resulting in a broken cord or short-
circuit.
rn ,
(MPBEN
Always grasp the plug.

Installation notes
Do not place this unit in a location that is exposed to direct
sunlight, near a heating appliance, etc.
oo
~
Do not store or use the unit in a dusty location or in a moist
atmosphere. Select a location where there is good ventila-
‘
-s
In case of an abnormal odor
If an abnormal odor or smoke is detected, immediately turn
the power OFF and pull out the power cord. Contact your
dealer or nearest Service Station.
Ox
(ges
To maintain good ventilation, do not put books or papers on
the unit. Position the unit at least 10 cm away from the
walls. ,
Cleaning
Do not use volatile solvents such as alcohol, paint thinner,
gasoline, benzine, etc. to clean the cabinet. Use a silicone
cloth or a clean dry cloth.
Silicone cloth Thinner Benzine

2. SPECIFICATIONS AND ACCESSORIES
2-1. SPECIFICATIONS
Model
TM-721A4
TM-721E
. Other markets
Specifications U.S.A. version version
144 to 148 MHz |144 to 148 MHz] 144 to 146 MHz
Frequency range 438 to 450 MHz |430 to 440 MHz | 430 to 440 MHz
Mode F3E (FM}
Antenna impedance 50 ohms
3 Power requirements 13.8 VOC +15%
S Ground Negative
& | [Transmit mode (Max.} O5A
5-5/ Receive made with no
58 Sena 0.6 A
Operating temperature 20°C to +60°C (-4°F to +140°F)
Dimensions (W x H x 0} "yO" ™
(Projections included) 180x 50x 219 mm (5.9%x 27x 8.6%}
Weight 1.8 kg (3.97 Ibs)
Output | HI 144 MHz: 45 W, 430/440 MHz: 35 W
power = [ LOW 5 Ww
FY Modulation Reactance modulation
€ | Spurious radiation Less than —60 dB
¢ Maximum frequency deviation +5 kHz
& | Audio distortion {at 60%
modulation) Less than 3% {300 to 3000 Hz)
Microphone impedance §00 to 600 ohms
Circuitry Double conversion superheterodyne
: 144 MHz: 16.9 MH2z/455 kHz,
intermediate | O=* version 440 MHz: 21.6 MHz/455 kHz
frequency 144 MHz: 10.7 MH2/455 kHz,
-, Other market 430 MHz: 30.825MH2/455 kHz
2 Sensitivity(12 dB SINAD) MMizeLess than 0.2 nV .450/440iiizsLess_ then 0.16 7
oe
a yt —6 dB: More than 12 kHz,
& | Selectivity ~60 dB; Less than 24 kHz
Spurious response Better than 60 dB
Squelch sensitivity Less than 0.09 gV
Output More than 2 W across 8 ohms load (5% distortion)
External speaker impedance 8 ohms
Notes:
1. Circuit and ratings are subject to change without
notice due to advancement in technology.
2. * : Recommended duty cycle:
1 minute : Transmission, 3 minutes : Reception
2-2. ACCESSORIES
Unpack your new transceiver carefully, and confirm that
the accessories listed below are included in the box.
MC-48B DTMF Microphone
(U.S.A, only) ............. peceeeeeeee T91-0359-05....1 ea.
or
Dynamic Microphone ...... seeeeeeeee 1 91-0365-15....1 ea.
Microphone Hook (U.S.A. only)...J20-0319-24 ....1 ea.
Self tapping Screw (U.S.A. only) .N46-3010-46....2 ea.
Mobile Mounting Kit ;
Bracket ........cscsceceveer even ree »-» JZ9-0418-03 ....1 ea.
SEMS Screw ....... venta eeeeeecene ..NO9-1530-05....4 ea.
Self tapping Screw ........-...06 NO9-0335-05....4 ea.
Flat Washer..........++ be ereeeeere ba eseeeeeeeee 4 ea.
DC Power Cable.............. seeereee-EGO-2111-05 ....1 ea.
Fuse (10A).......-c0esreeeeeeee beeeerees FO5-1031-05 ....1 ea.
Instruction Manual..............6. ....B50-8225-00...1 copy
Warranty Card (U.S.A. only)... veseel C8,
After unpacking
Shipping container:
Save the boxes and packing in the event your unit needs to
be transported for remote operation, maintenance, or ser-
vice.

3. INSTALLATION INSTRUCTIONS
3-1. 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
5
washer
—
pcs.
each).
.
ne
capping
—4
2. Attach the transceiver
loosely using the SEMS
screws (4 pcs.).
3. The angle of the bracket
may be adjusted to any of
9 possible viewing angles.
Select the desired angle. Fig. 1
(Fig. 2)
4. Hold the transceiver in
place and tighten the 4
SEMS screws using a
wrench or.screwdriver.
To 144 MHz To 430 MHz
3-2. CONNECTIONS
3-2-1. Mobile Installations
The MA-40C0 dual band
. To 144 MHz antenna
antenna is recommended.
4 External Speaker(_]
The SP-40 or
» the SP-5OB is Oe
i recommended.
Duplexer
| To 430/440 MHz
antenna
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.
Use of the cigarette lighter socket can lead to poor connec-
tion, and result in poor performance. Pay close attention to
the polarity of the cables when connecting them to the bat-
tery.
Make sure the positive (+) and negative (—) lead polarity is correct
when connecting to the battery.
Engine cornpartment ~—{—+~ Passenger compartment
Red Fuse
(
To the
transceiver
Select a location where
the power cable is pro-
tected from heat, mois-
ture or abrasion wi
securing the cable.
4
Chassis or
fire wall
by using a grommet.
@ If the wiring hole in the fire wall or chassis is too small,
disassemble the fuse holder to thread the wire through the hoie.
From passenger
compartment
Thread like this
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).
3-2-2. Fixed Station
A regulated DC power supply (13.8 VDC capable of sup-
plying at least 10 Amperes) is required. The PS-430 and
the PS-50 are recommended.
CAUTION:
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 connec-
tor, 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 polari-
ty must be correct. The power cable is color coded:
Red — + (Positive polarity)
Black ~ ~— (Negative polarity)
£ To 144 MHz antenna
PS-430 SP-430
To 430/440 MHz antenna

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
connection. If the antenna is far from the transceiver the
use of low loss coaxial cable, such as RG-8U is recom-
mended. 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:
For protection against fire, electric shock, personal injury,
or damage to the radio, use a lightning arrester in your
antenna lines.

4.
OPERATION
4-1. OPERATING CONTROLS
4-1-1. Front Panel
©
@
10
D @
ert
REV
ERI
cy | Meats
BANDE TM-7PtA] vO “Ge '2n"
cTcbs
BAS Se
& iran = FF
DO
@=——op =
Chae a lc
BUSY LOW AL
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ot
BALL
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AB MUTE
Main Tuning control
This control is used to select the desired transmit/
receive frequency, Memory Channel, Frequency Step,
Tone Frequency, and Scan direction of the MAIN fre-
quency band.
CALL key (TM-721A)
The CALL key selects the CALL channel of the MAIN
frequency band. The frequency has been factory-set
as follows, but may be reset to any desired frequency.
(See CALL Channel P25.)
U.S.A. version ; 440.000/144.000
Other market ; 430.000/144.000
TONE key (TM-721E)
European version: This key is used to transmit a Tone
signal. When the key is depressed the repeater con-
trol signal of 1750 Hz is activated.
U.K. version: This key is used to activate the
1750 Hz tone burst.
VFO key
This key is used to return to VFO operation after
| |
@ BY
operating in the MR (Memory Recall), or CALL Channel
mode (TM-721A only).
The MAIN tuning control will increase frequency in the
selected step size, the tone frequency (TM-721A
only), and/or the frequency step.
MR/M key
This key is used to select Memory Recall operation
after operating in the VFO or CALL channel mode. The
MAIN Tuning control may be used to select the desired
memory channel in this mode.
VOL control/Power switch ;
The volume control and power switch are combined.
Rotating the control clockwise will turn ON the
transceiver.
Advancing the control further clockwise will increase
the total volume of two bands. The BALANCE control
proportions the volume among the two bands.
MAIN SQL control
This control is used to select the desired SOL threshold
level of the MAIN frequency band.

@) Microphone connector
Plug the standard or optional microphone into this jack.
GND (PTT)
~~~
()GND
(Microphone)
@RX Audio output
(Approx. 150 mvV/600 ©)
~~ @8 V/Max. 15 mA
@ up
Front view
MHz key
This key is used to change frequency in 1 MHz steps
during VFO operations.
Pressing and holding the key will continuously change
the frequency in 1 MHz steps.
@) Sub Tuning control
This control is used to select the desired receive fre-
- quency and Memory channel of the SUB band.
LOCK switch
This key will deactivate all functions except the PTT
switch.
@) BALANCE control
This control proportions the total audio volume among
the two bands.
MAIN position : Audio only from the MAIN band
Center position : Equal audio from both bands
SUB position : Audio only from the SUB band
@2 SUB SOL control
This control is used to select the desired SQL threshold
level of the SUB band.
3 LOW key
This key is used to select the transmit output power
level as follows:
HI {no indicator) : 144 MHz:45 W/430 MHz:35 W
LOW : BW
Re
CALL, 1447440047 FH DUAL BANDER T= 721,
= - T + R€v cTess
SCAN
qd} DIM key
This key is used to select either high or low intensity of
both the LCD display and control’s illuminations.
For the key to function, it must be pressed within 5
seconds after pressing the F key.
(3) A.B.C. (Automatic Band Change)
When this key is pressed, the contents of the SUB
band will be transfered to the MAIN band whenever a
signal is received at the SUB band antenna, which is
strong enough to open the squelch. The contents of
the MAIN band are transfered to the SUB band at the
same time.
(§ DUAL band
This key is used to turn the SUB band ON or OFF.
> BAND key
This key is used to change the contents of the MAIN
band.
11

This key is used to start or
stop scanning.
This key is used to select
the desired transmitter of-
only)
This key is used to ac-
This key is used to reverse
the transmit/receive _ fre-
a: TM-721E
@
FE _ a ae t A _ os, SoAh SHIFT AL ay MUTE
So ojo cA so JARS
©) O)
@ SCAN Key @) SHIFT key @) TONE key (TM-721A || @ REV key ©) MUTE key
This key is used to reduce
the volume of the SUB
porarily skip unwanted
Memory Channels during
the Memory Channel Scan
mode.
Memory Channel 1 at ap-
prox. 5 second intervals.
lf the channel is busy, a
beep will sound.
TM-721E need not press-
ing the F key to activate
the AL key.
This key is used to switch
to the tone frequency
selection mode.
The MAIN Tuning control
can then be used to select
the desired tone frequen-
cy.
to the frequency selection
mode during VFO opera-
tion. The MAIN Tuning
control can then be used
to select the desired fre-
quency step.
fest during repeater tivate the subaudible tone quencies during repeater band (Approximately
operations. When the key encoder. operations. This will allow 20 dB).
is pressed the shift made you to check the input of
cycles from + to - [— to the repeater or to operate
— — (European version)] on a reverse repeater pair.
to simplex (no indicator).
a 4 Vv Vv Vv
® The F key is activate these keys below for 5 seconds after pressing the key, and during the ‘‘F’’ indicator is ON.
@
L.
OUT
key
AL
key
T.
SEL
key
(TM-
STEP
key
CTCSS
key
(TM-
This key is used to tem- This key is used to check 721A only) This key is used to switch 721A only}
With the TSU-6: This key
is used to activate
the CTCSS function.
Pressing the BAND
key to transfer the
contents of the SUB
band to the MAIN
band will release the
CTCSS function.
Tone will be ON dur-
ing transmitting.
Without the TSU-6: The
CTCSS function
does not actuate
even if the indicator
is ON.
12

LCD display
(indicators
? ? ORC) ® G}
f 1 [
wemm scan =| Lo ot + Revi cress|
HOO, | rhonoe
oy Para PER oe ee
xo ragga TT r= famaraaganres HEME
BUSY LOW i ABC] MUTE
i A common
g @ Indicator
| The MAIN band indicators |
Displays the operating frequency to
ae the nearest kHz, the frequency step,
and/or the tone frequency (TM-
es 721A only)
This level meter indicates the relative
receive input signal strength or
transmitter RF output.
ON whenever the squelch is open.
ON during transmit.
Om CALL ON when the CALL channel is ON.
@ SCAN ON when Scanning.
@- - Displays the selected transmitter off-
— -— set direction.
{TM-721E European version}
@ &T ON when the Tone function is ac-
tive.
® REV ON when the Reverse function is ac-
tive.
Indicates low power has been
selected.
ON when the Priority Alert system is
active.
ON whenever the F key is depressed.
(Always displays the last Memory
Channel number that had been
selected.)
Displays the current Memory Chan-
nel number.
The * indicator is ON when the
Memory channel will be skipped dur-
ing Memory Channel Scan.
| A common indicator |
ABC
ON when the A.B.C. (Automatic
Band Change) function is ON.
| The SUB band indicators |
Oe ee
Displays the receive frequency.
“S tomanmnifti-<————Indicates relative signal strenght dur-
‘ ing reception.
ON whenever the squelch is ON.
@ CTCSS
(TM-721A only)
MUTE
ON when the CTCSS function is ac-
tive.
ON when the volume of the SUB
band is reduced.
13

4-1-2. Rear Panel an |
Oo)
14
ANT (Antenna) connector
Attach an antenna with an impedance of 50 ohms to
this connector (PL-259).
A for 144 MHz
B for 430 MHz, 440 MHz
13.8 VDC power input connector
Connect the supplied DC Power Cable to this connec-
tor. Pay close attention to the polarity (the DC Power
Cable is color-coded; red is positive and black is
negative), when connecting the cable to the power
source.
Fuse holder
Contains a fuse (10A}
SP (Speaker) jack
This jack is for connection of an 8-ohm external
speaker.
4-1-3. Microphone
U.S.A. version only
@ and@ UP/DWN (Up/Down) switches
These switches are used to step the VFO frequency or
Memory Channel up and down. The frequency will
change continuously if the switches are pressed and
held.
PTT (Push To Talk) switch
The transceiver will be placed into transmit whenever
this switch is pressed. Operations such as scanning
will be cleared when this switch is pressed.
16-Tone DTMF Keypad (U.S.A. version only)
Used to activate the DTMF encoder. See Section 4-4
REPEATER for additional information on this item.

4-2. RECEIVER OPERATION
The
transceiver
will
supply
audio
confirmation
whenever
a
function
is
activated.
(See
BEEP
TONE
page
18.)
4-2-1. Reception
1.
Connect
the
power
supply
and
antennas,
and
then
set
the switches and controls as follows:
POWER (VOL) control: OFF (Fully counterclockwise}
POWER
switch
of
the
DC
power
supply
(Fixed
Station)
: OFF
MAIN
SQL
control
:
Fully
counterclockwise
SUB SQL control : Full left
BALANCE control : Full left (MAIN)
LOCK switch : OFF
POWER!
{VOL) contro!
Nes Tai ites FM DUAL BANGER Te T2tA] “OO oa,
wre oe . Ltt — MAIN SOL
Peon pal Oe
Ss = EN
a ©. 2. SS ogo oe 2
Sr N aT 7
1 { |
LOCK switch BALANCE control SUBS SQL control
Fig. 1
2. Turn ON the DC power supply and then turn the
transceiver’s
power
switch
ON.
The
display
panel
will
indicate
as
shown
in
Fig.
1.
Additionally
some
control
and
key
lights
will
turn
on.
Note:
If
the
display
is
not
as
shown
Fig.
1
reset
the
micropro-
cessor
using
the
procedure
give
in
Microprocessor
memory
Initialization
Page
22.
3.
Turn
the
VOL
control
clockwise
until
a
signal
or
noise
from
MAIN
band
frequency
is
heard.
4.
Rotate
the
MAIN
Tuning
control
and
select
an
open
channel.
Then,
turn
the
MAIN
SOL
contro!
clockwise
until
the
noise
disappears
and
the
BUSY
indicator
goes
OFF
(Threshold
point).
5.
Slide
the
BALANCE
control
full
right
(SUB).
6.
Rotate
the
SUB
Tuning
control
and
select
an
open
chan-
nel.
Then
slide
the
SUB SQL
control
to
the
right
until
the
noise
disappears
and
the
indicator
goes
OFF.
Dual
band
reception
|
(Simultaneous
reception
on
both
bands}
1. Slide the BALANCE control to the middle.
2.
Select
the
desired
frequencies
in
each
band.
When
each
signal
is
received,
the
BUSY
or
the
indicator
will
turn
ON
and
each
S-meter
will
deflect.
3.
To
distribute
volume
among
MAIN
band
and
SUB
band,
slide
the
BALANCE
contro!
to
the
desired
point.
The
VOL
control
reguitate
the
amount
volume
of
two
bands.
| Single band reception
Press
the
DUAL
key.
The
SUB
band
frequency
display
will
turn
off.
Caution:
Turn
off
the
transceiver’s
POWER
switch
before
you
turn
off
the
power
supply,
or
if
in
a
vehicle,
before
you
stop
the
engine.
15

4-2-2. Frequency Selection
Frequency can be changed in the VFO mode. The selected
frequencies of the main band can be stored in the Memory
channels, and the Call channel (TM-721A only).
(See Memory Entry page 23, CALL CHANNEL page 25.)
You can select the VFO mode, MEMORY Recall mode, and
CALL Channe! mode using the following keys.
MR/M key CALL key
/ VFO key VFO key
, CALL key
MEMORY Channel mode |
CALL channel made
MR/M
key
{TM-721A
only)
It is impossible to change the mode directly in the SUB
band.
It is possible to transfer the mode of the MAIN band
to/from SUB band.
Exchange the Band
Press the BAND key. Eachtime the BAND key is pressed,
the contents of the SUB band are exchanged with the
MAIN band.
@ MAIN BAND
@ VFO mode
1. Press the VFO key to select the VFO
mode.
2. Rotate the MAIN Tuning control, MHz
keys, or Microphone UP/DWN swit-
ches to select the desired frequency.
16
@ Memory Recall mode co
. Press the MR/M key. The previously =< | &) i
selected memory channel will be = #m 7
displayed on the LCD display. T in
2. Rotate the MAIN Tuning control or
Microphone UP/DWN_ switches to
select the desired Memory Channel.
3. To return to the VFO mode press the
VFO key.
=
@ CALL Channel mode (TM-721A only)
. Press the CALL key to select the CALL
Channel mode. The CALL indicator
and the call channel frequency are
displayed on the LCD display.
2. To return to the previous mode press
the CALL key again.
Note:
The Memory Channel number will not disappear during
the CALL channel mode, if the call channel is selected
from the MR mode.
~~
2 z
r
tg)
ie
-
O
IG
=
2]
0
f
@ SUB BAND
@ \f the current frequency is in VFO
mode; Rotate the SUB Tuning control
to select the desired frequency. ave
@ if the current frequency is in MR
mode; Rotate the SUB Tuning control
to select the desired Memory Channel.
(The Channel number is not ae
displayed.)

@ Current frequency is in CALL Channel mode (TM-721A
only);
Frequency
can
not
be
changed
in
the
SUB
band.
(The CALL Channel indicator is not displayed.)
4-2-3. Frequency Step Selection
The
frequency
step
is
factory-set
to
the
following;
TM-721A TM-721E
144 MHz Band 5 kHz 12.5 kHz
430/440 MHz Band 25 kHz 25 kHz
The
frequency
step
can
be
selected
by
using
the
following
procedures:
. Rotate the Tuning control
or press the Microphone
UP/DWN switch to select
the desired frequency
step. The accompanying
figure shows how the
Tuning control will in- [7
crease or decrease the
5-~-10--15~-20--25~-12. *]
.
(Hz}
step
size.
.
To
complete
the
Frequen-
-
.
Microphone
cy
step
selection
press
the
MAIN
tur
UP/DWN
Ing
cont
5
VFO
key
or
any
other
key.
ing
contro!
|
switches
Automatically
return
5
|
—,
|
Rotate
Press
UP
.
clockwise
key
seconds
of
the
selection.
Rotate
Press
DWN
<-_
counter-
.
key
clockwise
1. Press the VFO key to
select the VFO mode. vro
If you are already in the
VFO mode you can skip
this step.
2. Press the F key. The F in-
dicator will be displayed on
the LCD display.
Press the REV/STEP key 25 Seay aD 2
within 5 seconds. (If the in- [i eeecerISTEt cs omer
dicator goes off, you must
press the F key again.) The
current frequency step will
be displayed on the LCD
display.
It is impossible to select the Frequency Step directly while
in the SUB Band. It is possible to transfer the selected Fre-
quency Step of the MAIN band to the SUB band. Press the
BAND key.
7

4-2-4. A.B.C. (Automatic Band Change)
The A.B.C. function allows you to exchange the contents
of SUB band to the MAIN band automatically whenever a
signal is received in the SUB band and SUB squelch is open.
1. Press the A.B.C. key.
The A.B.C. indicator will AB.C.
turn on displayed in the co
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2. As soon as a signal is _
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exchange the bands. *
ff press the PTT switch, If does not press the PTT
A.B.C. function is released. switch 3 seconds after the
signal goes off, the MAIN
band return to SUB band.
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Caution:
* The Tuning controls are not effective during this exchange.
18
4-2-5. BEEP TONE
If you would not like audio confirmation when a function is
activated, turn the POWER switch OFF. Then press and
hold the MUTE key and turn ON the power switch, then
release the mute key.
Repeating this procedure will turn the function back ON.
The transceiver supplies audio confirmation according to
the accompanying chart.
Scale Freaueney Key operation
A 440.00 CALL, REV, TONE, CTCSS, F, SCAN, L.OUT, AL,
A.B.C., MUTE, DIM:OFF
A# 466.16 144 MHz MAIN BAND, SUB BAND OFF, LOW POWER
ON
B 493.88 SCAN STOP
Cc 523.25 VFO MODE SELECTION
C# 554.37 — OFFSET
D 587.33 SIMPLEX
D# 622.26 + OFFSET
E 659.25 MR MODE SELECTION
F 698.46 To complete the MEMORY Entry
To compiete the CTCSS Frequency selection
F# 739.98 430 MHz selection, SUB BAND ON, HI POWER ON
G 783.98 CALL, REV, TONE, CTCSS, SCAN, L.OUT, AL, A.B.C.,
MUTE ON
G# 830.61 MEMORY CHANNEL, Tone frequency, Frequency step
selection
A 880.00 F mode, Split channel ON
Ad# 932.33 Band change during A.B.C.
F 1396.91 Key operation without effect

4-3. TRANSMITTER OPERATION
Caution:
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 in the MAIN
band 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.
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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
transmit 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.
5. Release the PTT switch to return to the receive mode.
The ON AIR indicator should go out, and the RF meter
will return to zero.
Duplex Operation
Pushing the PTT switch on the microphone allows the
simultaneous reception in the SUB band frequency and
sending in a MAIN band frequency.
Note:
With certain relationship between the sending and receiv-
ing frequencies, the receiver sensitivity may be suppress-
ed,
19

4-4. REPEATER OPERATION
4-4-1. TRANSMITTER OFFSETS
All amateur radio repeaters utilize a separate receiver and
transmitter section. The receiver frequency may be either
above or below the transmitter frequency.
For most repeaters offsets are as follows:
Band 144 MHz 430/440 MHz
Model TM-721A TM-721A TM-721€
Displ TM-721E European U.K.
isplay version version
+ +600 kHz +5 Miz +1.6 MHz
_ —600 kHz -—5 MHz —1.6 MHz —1.6 MHz
- - ‘ —7.6 MHz
@ Offset Direction
To select the desired transmitter offset direction press the
SHIFT key. Each time you press the key the transceiver will
advance from one offset to the other, i.e. + to —
(- to —- — with European version) to no offset
(simplex).
The transceiver allows you to store the frequency, and off-
set In memory, or you can select these functions directly
from the keyboard.
20
4-4-2. REVERSE FUNCTION
Some repeaters utilize a ‘‘Reverse pair’’, i.e. the transmit/
receive frequencies are exactly the reverse of another
repeater. For example repeater A uses 146.000 for a
transmit frequency (OUTPUT) and 146.600 for receive
(INPUT). Repeater B uses 146.000 for its receive and
146.600 for its transmit frequency. It would be inconve-
nient to have to reprogram the transceiver each time if you
were in range of both repeaters.
The REV key allows you to reverse the transmit and receive
frequencies. To use the REVERSE function press the REV
key. The offset indicator ( + or — / — or —
— } will flash OFF and ON in the display to remind you
that you are working a reverse repeater pair.
To return to normal offsets press the REV key again. This
function is also useful to check the input frequency of the
repeater, so that you can determine if you are within
SIMPLEX communications range.
4-4-3. TONE OPERATION
Some repeaters require the use of a control signal to ac-
tivate the repeater. Several versions are currently in use
worldwise.
In the United States sub-audible tones are sometimes used.
With the TH-721A, 38 different sub-audible tone frequen-
cy selections are possible.
With the use of the optional sub-audible tone en-
coder/decoder (TSU-6) also allows for CTCSS (Tone
Squelch) operations. When this option is activated the
squelch of the SUB band will only open when the proper
sub-audible tone is received.