Kenwood TM-621A User manual

GOO/ANA
144/220MHz FM DUAL BANDER
M-621A
144/440MHz FM DUAL BANDER
IM-721A
144/430MHz FM DUAL BANDER
IM-721A
TM-721E
INSTRUCTION MANUAL
KENWOOD CORPORATION
@©PRINTED IN JAPAN B50-8225-10(K, M, T.W)(T)
89/121110987654321 881211098

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-621A : 144/220 MHz FM DUAL BANDER
TM-721A : 144/440 MHz FM DUAL BANDER
(U.S.A. version)
TM-721A : 144/430 MHz FM DUAL BANDER
(Other market)
TM-721E : 144/430 MHz FM DUAL BANDER
(with Tone Burst for U.K. version)
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.
Illustrations show the TM-721A.

CONTENTS
Pioh>
BEFORE OPERATION 4
SPECIFICATIONS and ACCESSORIES . a6
INSTALLATION INSTRUCTIONS ... as
OPERATION ie vin csnntgs nnn esispicensnspiivsadveredeavenses 10
OPERATING CONTROLS
RECEIVER OPERATION. s.vesencoscossneivses esses een 15
Reception
Frequency Selection
Frequency Step Selection ie
A.B.C. (Automatic Band Change) .............0+ 18
Beep Tone
TRANSMITTER OPERATION
REPEATER OPERATION ...0.ce3tvasivauasitecseaseeas
Transmitter Offsets
Reverse Function
Tone Operation
Autopatch (U.S.A. version only)
MEMORY 7.05 s25e sins shswcasennasacsdcteuansecuvee este
Microprocessor Memory Back-up
Microprocessor Initialization
Memory Channel
Memory Contents
Memory Enithyiscistesesescectssssevecssnexsas ceases 23)
Simplex/Normal SHIFT
Odd Split Channel
Call. CHANG) aides nnsnexrcinesnasnsinediiencwexe 25
Memory Recall
Memory Shift
Scan Options
Programmable Band Scan/Band Scan
Memory Channel Scan
Hold Resume Programming
Priority Alert, ccscssousesveceurascsarsacetiaewsserews 27
Memory Channel Lockout
BLOCK DIAGRAM
and
SCHEMATIC
DIAGRAM
°7"""""
another
sheet
MAINTENANCE.....
in Case of Difficulty ....
OPTIONAL ACCESSORIES....
CTCSS unit TSU-6 (U.S.A. version) ...
REMOTE CONTROLLER RC-10....
REFERENCE

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-
BBUny
of
2
tally, a serious electric shock might occur.
DC Power Supply:
Touching
the
power
plug
when
your
hands
are
wet
may
result
in
a
serious
electric
shock.
Never touch internal parts.
F
vie
F
~Qury
If
a
metal
object,
such
as
a
hair
pin
or
a
needle,
comes
into
4
\
contact
with
the
power
socket
on
the
rear
panel,
a
o*
%\___
Never
touch
with
wet
hands.
dangerous
electric
shock
may
result.
Never
permit
children
jp
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.
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.
Oe
.
pV
Do not store or use the unit in a dusty location or in a moist
atmosphere. Select a location where there is good ventila-
tion.
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.
(3
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
TM-721A
‘eure Other markets TM-721E TM-621A
version
Frequency range
144 to 148 MHz|144 to 148 MHz|144 to 146 MHz|144 to 148 MHz.
438 to 450 MHz/|430 to 440 MHz|430 to 440 MHz/220 to 225 MH:
Mode
F3E (FM)
Antenna impedance
50 ohms
Power requirements
13.8 VDC +15%
Ground
Negative _
Less than 9.5 A
5G] Receive mode with no
135] signal
rf Transmit mode
Less than 0.6 A
Operating temperature
— 20°C to +60°C (—4°F to +140°F)
Dimensions (W x H x D)
(Projections included)
150 x 50 x 219 mm (5.9 x2" x 8.6")
Weight
1.8 kg (3.97 Ibs)
Output
power*
144 MHz: 45 W, 220 MHz: 25 W, 430/440 MHz: 35 W
5W
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
500 to 600 ohms
Circuitry
Double conversion superheterodyne
U.S.A, version
Intermediate
144 MHz: 16.9 MHz/455 kHz,
220 MHz: 30.825 MHz/455 kHz,
440 MHz: 21.6 MHz/455 kHz
frequency
Other market
144 MHz: 10.7 MHz/455 kHz,
430 MHz: 30.825MHz/455 kHz
2)| Sensitivity(12 dB SINAD)
144 MHz: Less than 0.2 uV, 220 MHz: Less than 0.18 2V,
430/440 MHz: Less than 0.16 wV
Selectivity
—6 dB: More than 12 kHz,
— 60 dB: Less than 24 kHz
Spurious response
Better than 60 dB
Squelch sensitivity
Less than 0.09 «V
Output
More than 2 W across 8 ohms load (5% distortion)
External
Notes:
8 ohms
1. Circuit and ratings are subject to change without notice due to ad-
vancement in technology.
2. *: Recommended duty cycle:
1 minute : Transmission, 3 minutes : Reception
2-2. ACCESSORIES
Unpack your new transceiver carefully, and con-
firm that the accessories listed below are included
in the box.
MC-48B DTMF Microphone
(U.S.A. only) .........0086 791-0359-15..... 1 ea.
or
Dynamic Microphone...... T91-0365-15..... 1 ea.
Microphone Hook
(U.S.A. (only): ......2.00008 J20-0319-24...... 1 ea.
Self tapping Screw
(U.S.A. only) .. -N46-3010-46 .
Mobile Mounting Kit
Bracket
SEMS Screw ..
Self tapping Screw.
-N99-0318-05.....1 ea.
-J29-0418-03...... 1 ea.
-NO9-1530-05.....4 ea.
-NO9-0335-05 .....4 ea.
Flat Washer.sc..,csossensnsaenivsovpaccaresysaonees
DC Power Cable -E30-2111-05 .
Fuse (10A) -FO5-1031-05.....
Instruction Manual ......... B50-8225-XX ..1 copy
Warranty) Cards: caamccsssssevecscgarsececcssnetone 1 ea.
After unpacking
Shipping container:
Save the boxes and packing in the event your unit
needs to be transported for remote operation, main-
tenance, or service.

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 Flat
and self tapping screws (4 __ washer —~
Self tapping —-
pcs. each). seid
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.
3-2. CONNECTIONS
3-2-1. Mobile Installations
TM-721A/721E:
The MA-4000 dual band
antenna is recommended.
To 144 MHz antenna
The SP-40 or
= the SP-50B is
_ recommended. _
¥ External a)
Duplexer \
- Pp
+
TM-621A: TM-721A/721E:
To
144
MHz
To
430
MHz
To
220
MHz
To
430/440
MHz
antenna = 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.
Red
Engine compartment -—}|—-~ Passenger compartment
Fuse
To the
transceiver
Select a location where
E power cable is pro- brargpondet bran pmo
does not directly con
tact the edge of the hole
¢ by using a grommet.
Chassis or
fire wall
tected from heat, mois-
ture or abrasion when
securing
Battery
the cable.
@ lf the wiring hole in the fire wall or chassis is too small,
disassemble the fuse holder to thread the wire through the hole.
From passenger
compartment
oy ——————
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:
. Never connect the AC power cable to the AC outlet until
1
2.
all other connections have been made.
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.
. 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)
f
+
To
144
MHz
antenna
+
[ ? TM-621A or SP-430
6
—
TM-621A : To 220 MHz antenna
TM-721A/721E : 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 ® ®@ 3@ a 46 a 6
+ +) || mom scan = 7 goliney | ereas
ea ky 06. eo
es Aoaeaae seeoaga|
! Le
He t gE
ee
® wo i @ (09
(@) Main Tuning control ® VFO key
This
control
is
used
to
select
the
desired
transmit/
This
key
is
used
to
return
to
VFO
operation
after
oper-
receive frequency, Memory Channel, Frequency Step, ating in the MR (Memory Recall), or CALL Channel mode
Tone Frequency, and Scan direction of the MAIN fre- (TM-621A/721A only).
quency band. The MAIN tuning control will increase frequency in the
@ CALL key (TM-621A/721A) selected step size, the tone frequency (TM-621A/721A
The CALL key selects the CALL channel of the MAIN only), and/or the frequency step.
frequency band. The frequency has been factory-set as @ MR/M key
follows, but may be reset to any desired frequency. (See This key is used to select Memory Recall operation af-
CALL Channel P25.) ter operating in the VFO or CALL channel mode. The
TM-621A ; 220.000/144.000 MAIN Tuning control may be used to select the desired
TM-721A memory channel in this mode.
U.S.A. version ; 440.000/144.000 ® VOL control/Power switch
Other market + 430.000/144.000 The volume control and power switch are combined.
TONE key (TM-721E) Rotating the control clockwise will turn ON the tran-
European version: This key is used to transmit a Tone sceiver.
signal. When the key is depressed the repeater con- Advancing the control further clockwise will increase
trol signal of 1750 Hz is activated. the total volume of two bands. The BALANCE control
U.K. version: This key is used to activate the proportions the volume among the two bands.
1750 Hz tone burst. © MAIN SOL control
This control is used to select the desired SOL threshold
level of the MAIN frequency band.
10

@) Microphone connector
Plug the standard or optional microphone into this jack.
GND (PTT)
(1)
Microphone
audio
—
—(7)GND
(Microphone)
@ PTT (STBY) switch
~ (Approx. 150 mV/600 Q)
(©)8 V/Max. 50 mA
@ DOWN
(@) UP
Front view
(8) 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
SUB SQL 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/220 MHz:25 W/
430 MHz:35 W
LOW : 5W
rs)
Ties ADA BAER To) Oe
EE fais 528880 ©
[site eS vie =| oy
eT ae I/O
ooo (°° 2]
Hm a Gy
A.B.C. DUAL BAND
(4 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.
1 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

T™M- ~ oO ®
Lod
d hi
Tt
eae pe ea "OUT
I ae
TM- ne
-
@ 5
poebe
® wo
@ SCAN Key
This key is used to start or
stop scanning.
(2) SHIFT key
This key is used to select
the desired transmitter of-
fest during repeater
operations. When the key
is pressed the shift mode
cycles from + to — [— to
— — (European version)]
to simplex (no indicator).
_ TONE key (TM-621A/
721A)
This key is used to ac
tivate the subaudible tone
encoder.
@ REV key
This key is used to reverse
the transmit/receive fre-
quencies during repeater
operations. This will allow
you to check the input of
the repeater or to operate
on a reverse repeater pair.
(5) MUTE key
This key is used to reduce
the volume of the SUB
band (Approximately
20 dB).
This key is used to tem-
porarily skip unwanted
Memory Channels during
the Memory Channel Scan
mode.
12
This key is used to check
Memory Channel 1 at ap-
prox. 5 second intervals.
If the channel is busy, a
beep will sound.
TM-721E need not press-
ing the F key to activate
the AL key.
721A)
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.
Vv Vv 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-621A/|
|
((
STEP
key
(1)
CTCSS
key
(TM-621A/
This key is used to switch
to the frequency selection
mode during VFO opera-
tion. The MAIN Tuning
control can then be used
to select the desired fre-
quency step.
721A)
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.

LCD display
| The MAIN band indi The SUB band
Indicators
7) ||A common 10)
Indicator | Wo)
The MAIN band Indicators
the nearest kHz, the frequency step,
g and/or the tone frequency (TM-621A/
i) 721A);
This level meter indicates the relative
receive input signal strength or
transmitter RF output.
ON whenever the squelch is open.
ON during transmit.
ye Displays the operating frequency to
1
Om CALL ON when the CALL channel is ON.
(TM-621A/721A)
@ SCAN ON when Scanning.
@®-
+
Displays
the
selected
transmitter
off-
a at, set direction.
(TM-721E European version)
® T ON when the Tone function is ac-
tive.
® REV ON when the Reverse function is ac-
tive.
© LOW Indicates low power has been
selected.
@
AL
ON
when
the
Priority
Alert
system
is
active.
ON whenever the F key is depressed.
F 7 (Always displays the last Memory
ay Channel number that had been
selected.)
— Displays the current Memory Chan-
* 4 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
Displays
the
receive
frequency.
PEEEEET
2 titmmmnlltill <-————!Ndicates relative signal strenght dur-
ing reception.
ON whenever the squelch is ON.
@ cTcss
ON when the CTCSS function is ac-
(TM-621A/721A)
tive.
a MUTE ON when the volume of the SUB
band is reduced.
13

4-1-2. Rear Panel +
14
ANT (Antenna) connector
Attach an antenna with an impedance of 50 ohms to
this connector (PL-259).
A for 144 MHz
B for 220 MHz (TM-621A)
430 MHz, 440 MHz (TM-721A/721E)
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 nega-
tive), 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) control
wr wit
a! Sf tl oto ot
control
LOCK switch BALANCE control SUB 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.
MAIN SQL
3. Turn the VOL contro! clockwise until a signal or noise
frorn MAIN band frequency is heard.
4. Rotate the MAIN Tuning control and select an open
channel. Then, turn the MAIN SQL control 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 |B] 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 |B] indicator will turn
ON and each S-meter will deflect.
3. To distribute volume among MAIN band and SUB band,
slide the BALANCE control to the desired point.
The VOL control regultate 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.

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-621A/721A).
(See Memory Entry page 23, CALL CHANNEL page 25.)
You can select the VFO mode, MEMORY Recall mode, and
CALL Channel mode using the following keys.
VFO mode
MR/M key CALL key
uf VO kev! VEO key.
CALL key
| mode |= | CALL channel mode
MEMORY Channel NOs MRI/M key __(TM-621A/721A)
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 +H
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
3. To return to the VFO mode press the
[KENWOOD
® Memory Recall mode
. Press the MR/M key. The previously
selected memory channel will be
displayed on the LCD display.
2. Rotate the MAIN Tuning control or
Microphone UP/DWN_ switches to
select the desired Memory Channel.
mn
VFO key.
@ CALL Channel mode (TM-621A/721A)
1. Press the CALL key to select the CALL
Channel mode. The CALL indicator and
the call channel frequency are dis-
played 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.
@ SUB BAND
@ If the current frequency is in VFO
mode; Rotate the SUB Tuning control sii
to select the desired frequency.
@ |f the current frequency is in MR mode;
Rotate the SUB Tuning control to select ©
the desired Memory Channel. (The
Channel number is not displayed.)

® Current frequency is in CALL Channel mode (TM-621A/
721A); 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;
es : | _TM-621A _TM-721A TM-721E
144 MHz Band 5 kHz 5 kHz 12.5 kHz
| _220MHz Band | 20 kHz - | =
430/440 MHz Band | — 25 kHz _ 25 kHz
The frequency step can be selected by using the following
procedures:
MAIN Band
1. Press the VFO key to select veo
the VFO mode.
If you are already in the
VFO
mode
you
can
skip
ae
inaea
this
step.
ec
Say
SH
{Ri
oe
MER
POMEL
TR
EI
SD
Sea
dicator will be displayed on
the LCD display.
Press the REV/STEP key wi-
thin 5 seconds. (If the in-
dicator goes off, you must
press the F key again.) The
current frequency step will
be displayed on the LCD
display.
3. Rotate the Tuning control a
or press the Microphone i i
UP/DWN switch to select
the desired frequency
step. The accompanying EESEDaesccssnsas|
figure shows how the
Tuning control will in-
crease or decrease the
a 0-15--20--25~-1 <a
. (Hz)
step size.
4. To complete the Frequen-
2 Microphone
cy step selection press the MAIN Tun: | Up/pWN
i
VFO key or any other key. ing control | “switches
Automatically return 5 | _, | Rotate Press UP
" ‘lock wi: k
seconds of the selection. San = ee
jotate
=. counter- Press DWN
key
clockwise
SUB Band
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.
17

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
turn on displayed in the
LCD display.
4-2-5. BEEP TONE
lf 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.
2. As soon as a signal is
received in the SUB band,
exchange the bands. *
Frequency
If press the PTT switch,
A.B.C. function is released.
If does not press the PTT
switch 3 seconds after the
signal goes off, the MAIN
band return to SUB band.
M4900 Wasa
Ls sn
Wee un
vies
7
Caution:
* The Tuning controls are not effective during this exchange.
18
Scale (Hz) Key operation
A “| 440.00 | CALL, REV, TONE, CTCSS, F, SCAN, LOUT, AL,
ee A.B.C., MUTE, DIM:OFF
At 466.16 | 144 MHz MAIN BAND, SUB BAND OFF, LOW
POWER ON _
493.88 | SCANSTOP
J]ODE SELECTION
SET
887.33 | SIMPLEX
622.26 | + OFFSET
E | _659.25 | MRMODE SELECTION _ A
F 698.46 | To complete the MEMORY Entry
To complete the CTCSS Frequency selection |
Fe 739.98 | 220 MHz selection (TM-621A), 430 MHz selection
Ss (TM-721A/721E), SUB BAND ON, HI POWER ON
G 783.98 | CALL, REV, TONE, CTCSS, SCAN, L.OUT, AL,
A.B.C., MUTE ON ri £
Gt 830.61 | MEMORY CHANNEL, Tone frequency, Frequency step
S selection
A 880.00 | F mode, Split channel ON
At 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.
4428
= Fi er
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.
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.
19

For most repeaters offsets are as follows:
Band | 144MHz | 220 MHz 430/440 MHz
Model| TM-621A TM-721E
TM-721A | TM-621A | TM-721A | European UK.
Display \| TM-721E version version
+ | +600 kHz | +1.6 MHz| +5 MHz +1.6 MHz
— | 600 kHz | —1.6 MHz| —5 MHz | —1.6 MHz | —1.6 MHz
- = el ~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.
@ Auto-Offset (TM-621A only)
The TM-621A has been programmed according to the stan-
dard ARRL Band Plan, regarding transmitter offsets. Please
see the accompanying chart for additional information. You
can, of course, override this by using the SHIFT function,
if desired.
S: Simplex Channel
144.00 145.10 146.00 146.60 147.40 148.00
1 A fi ‘ i
Si 8. l=] 8 ja] — Tals = 18
145150 146.40 147/00 147.60
220.000 223.920 224.995
s s = s
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 TM-621A/721A, 38 different sub-audible tone
frequency 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.