Kenwood TH-25A Series User manual

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144MHz FM TRANSCEIVER
TH-25A
SERIES
TH-45A SERIES
430/440MHz FM TRANSCEIVER
1200MHz
FM TRANSCEIVER
TH-55A T SERIES
INSTRUCTION MANUAL
KENWOOD CORPORATION
© PR INT ED IN JAPAN BSD-817D-3O(K , M,W,T, X )(T)
89 / 12 11 10 9 8 7 6 S 4 3 2 1 88 112 11 10 9 8 7 6 S 4 3 2

Thank you for purchasing this new transceiver.
IMPORTANT: _________ _
Please read thi s in struction manual carefully before placing
your transceiver in service.
SAVE THIS INSTRUCTION MANUAL.
This Instruction Manual covers the following model s:
TH - 25AT : 144 MHz FM transceiver with DTMF Pad .
TH- 25A : 144 MHz FM transceiver without DTMF Pad .
TH - 25E : 144 MHz FM transceiver with Tone.
(with Tone
Burst for U.K. version)
TH- 45AT :430 / 440 MHz FM transceiver with DTMF
Pad .
TH- 45A : 430 / 440 MHz FM transceiver without DTMF
Pad .
TH-45E : 430 MHz FM transceiver with tone.
(with Tone Burst for U.K. version)
TH- 55AT : 1200 MHz FM transceiver with DTMF Pad .
TH-55E : 1200 MHz FM transceiver with Tone.
(with Tone Burst for U. K. vers ion)
Under normal circumstances, the transceiver will operate in
accordance with these operating instruction s. The
transceiver
has been adjusted at the factory and sh o uld on-
ly be readjusted by a qualified technician with proper test
equipment.
Attempting service
or alignment without factory authoriz a-
tion can void the transceiver's warranty.
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.
Use of an external antenna for fixed station is recommended.
Illustrations show the TH- 25A.
CONTENTS
1. SPECIFICATIONS and ACCESSORIES .................... . 4
2. BATTERY PACK.....
................. .... ........ .... ......... ... 6
3. OPERATION
OPERATING CONTROLS...
........ . ..... .... .......... ....... 8
RE CEIVER OPERATION. ................... . ......... .... ....... 12
TRANSMITTER OPERATION
ME MORy ....... ....... ........ ............. ..... .......... ......... 13
AUTOMATIC MEMORY INITIALIZATION
MEMORY ENTRY
MEMORY SHIFT. ........ .... .... ......... ..... ......... ...... 14
MEMORY RECALL
ODD SPLIT
MEMORY CHANNEL LOCKOUT . ........ ....... ...... ... 15
CLEARING ALL MEMORy ....... ... ....... ....... ......... 16
MEMORY BACK- UP BATTERY
SCAN
REPEATER OPERATION.... ........ ....... .............. .. .17
TRANSMITTER OFFSETS
REVERSE FUNCTION
TONE OPERATION
AUTOPATCH ......
.......... .... ............ .. .......... . 19
BEEP TONE
TONE ALERT SYSTEM ....
.......... .... ............ . ...... 20
BATTERY SAVER
AUTOMATIC POWER OFF
BATTERY SAVER and AUTOMATIC POWER OFF
function CANCEL (TH- 55AT /55E only)
4. BLOCK DIAGRAM and
SCHEMATIC DIAGRAM ............ .... ..... ... Another sheet
5. MAINTENANCE .....
....... . ............. .... ......... . .......... 22
IN CASE OF DIFFICULTY ....... . ........... ............... 23
6. OPTIONAL ACCESSORIES ......... . ......... ......Back cover
3

1. SPECIFICATIONS and ACCESSORIES
1-1 SPECIFICATIONS
• GENERAL TH-25A 125 AT 125E TH - 45A 1 45AT 145E
TH-55AT I55E
2 m Band 70 em Band 23 em Band
FREQUENCY RANGE (MHz) U.S.A.version
'44 .000,,'47.995
440.000~49.995 1258.()()(h.1300.000
European and U.K. version 144 . 000 " 145.995 430.000~39.995 1258.()()(h.13oo .000
Others 144.00 0" 147 . 995
430 . 000~39.995
1258.()()(h.13oo .000
MODE
F3E (FM)
MEMORY CHANN EL S
14
FREQUENCY STEP (kHz) TH -25A/25AT ITH-25EITH-45A/45ATITH -45 EI
5. 10
112.5. 51
25 . 5 1
12 .5. 51
25 . 12 .5
ANTENNA IMPEDANCE
(01
50
POWER REQUIREMENT
6",16 (7.2 VDC nominal)
CU RRENT DRAIN HI 12 V (with PB-8 or DC - ') Les s than 1 .2 A Less than 1.8 A Less than 1.0 A
9 V (with BT-6) Appro x. 0.9 A Approx. 1.4 A Less than 1
.0 A
7.2 V (with PB-5161719) Approx. O.S A
Approx. 1.1 A Approx. 0.8 A
LO transmit mode Less th an 0.4 A Less than 0.6 A Less than 0.6 A
RECEIVE mode with no signal Approx. 55 rnA Approx. 60 rnA Approx. 60 rnA
BA
TIERY SAVER mode Approx. 16mA Approx. 17 rnA Approx.
17 rnA
AUTOMATIC POWER OFF mode Approx. 6 rnA
Approx. 5 rnA
FREQUENCY STABILITY (
lODe _ + 60
D
C)
±3 ppm
GROUND Negative
DIMENSIONS (W x H x D)
Projections not included {mm} 58 x 13 7.5 x 29.5 (2.3x 5.4 x 1.2 inch) 58 x
157 .5 x 29.5
Projections included (mm) IAlE 68.5 x 15 2.0 x 34.5 (2.7 x 6.0x 1.35 inch)
68.5xl72x37.5
I AT
68.5 x 1 52.0x 35.5 (2.7 x 6.0 x 1.4 inch) (2.7x7.0xl . Sinchl
WEIGHT (g) With NiCd Battery and Antenna
400 (0.88 Ibs.)
450 (0.99 Ibs)
OPERATING TEMPERATURE -
20
De _ +
50°C( -4 ° F -122°F)
MICROPHONE IMPEDANCE 2 kO
.TRANSMITTER
OU TPUT POWER HI 12 V (with PB -8 or DC·' ) More
than 5 W
lW
9 V (with BT·6) Appro x. 3.5 W I Approx. 3.5 W
lW
7.2 V Iwith PB -516 171 9) Appro x, 2.5 W I Approx. 2 W
Approx . 0.8 W
4

OUTPUT POWER I LO Approx.
0.5W
I Appro
x. 0.1 W
MODULATION REACTANCE
MAXIMUM FREQUENCY DEVIATION (kHzl
±5
SPURIOUS RADIATION l
ess than - 60 dB
I Le ss than - 50 dB
DUTY CYC LE OPERATION 1 minute t
ransmiss io n 3 minutes reception recommended
• RECEIVER
CIRCUITRY DOUBLE CONVERSION SUPERHETERODYNE
INTERMEDIATE FREQUENCY I
1st IF (MHzl
16.9
I
30 .8 25
I
59.7
I 2nd IF (kHzl
455
SENSITIVITY 12 dB SINAD
Less than 0.16 p.V I Less than 0 . 18 p.V I Less than
0.25 p.V
SQUELCH SENSITIVITY
Less than 0.1 p.V
I
Less than 0. 16 JlV
SELECTIVITY I
-6 dB More than 12 kHz
I - 40 dB Less than 28 kHz I
Less than 32 kHz
RIT variable range I More than ± 5 kHz
AUDIO OUTPUT POWER (ac ro ss 8 nload 10 % distortion) More than
200 mW
Note: Circuit and ratings are subject to change without notice. due to development In technology.
1-2 ACCESSORIES
Unpack your transceiver ca refully and confirm that the accessories list ed bel ow are included in the box.
1 Antenna ............................... .. ..... ........ ..... ........... 1 for U.S.A . version (120 VI ... WOS - 0382 -XX
For 144 MHz ..................... TSO - 03S6-0S for European version (220 VI .. WOS-0388-XX
or For 430 / 440 MHz ............ .. TSO -03SS-0S for U.K. version (240 Vi ....... WOS-0387 -XX
or For 1200 MHz ..... . ........... .. TSO - 0364-0S for Oceania version (240 VI .. WOS-0386-XX
2 Belt Hook. ........ ..... ..... ........... J2S - 0424-04 ........... 1 for Other market (220 VI ..... WOS-0384-XX
3 Rubber Cap .............. ..... ........ B09 - 030S - 04 ........... 1 (120 Vi ..... WOS-038S- XX
4 Hand Strap ............... .. .. ......... J69 - 0312-04 ........... 1 7 Label .......... . ........ .. ..... .... ...... B42 - 332S-04 ........... 1
S Battery ............ ..... ........... .... ......•......................... 1 8 Warranty Card .......... ............. .. .. . .. ..... ............. .... .. 1
NiCd battery pack
(PB-61 ...... WOS -OS07-0S S Instruction Manual .................. BSO·8170-XX .. ...... .. 1
6 Battery Charger.........
..... ... ............. .... .. ............... ..1
After unpacking
Shipping container: Save the boxes and packing
in the event your unit ne eds to be transported for remote operation,
maintenance,
or service. 5

2. BATTERY PACK
2-1 NiCd BATTERY PACK (PB-G)
This battery pack has not been charged at the facto ry in
order
to provide you with the greatest number of
charge/discharge cycles. You must charge the battery
before use. The battery pack will require several
charge/discharge cycles before you can expect
to see the
maximum operating period between charges. If the battery
will be stored for greater than 2 month s it should be
re charged before use.
2-2 RECHARGING
1. Slide the adapter onto the
NiCd battery pack.
2. Plug
the supplied charger
into an AC o utlet .
3. Do not allow the battery
to charge for greater than
15 hours.
The useful life and battery
performance will be reduc-
ed if you exceed the recom-
mended charge period.
Note: -- -- ------
Recharging should be performed
within an ambient temperature
range of between 50 C - 40 °C
(41°F_104° F ).
Recharging the battery outside
of this range ma y n ot allow the
battery to reach full cha rge.
6 to
AC outlet
2-3 MANGANESE or ALKALINE BATTERIES
(Optional Battery Case BT
-G)
In st all 6 x A6 (AA) man- Press down on the hook in the
9anese or alkaline batteries in middle of the battery case top
th e battery holder. Pay close to open.
attention the battery polari-
tie s marked in the holder. We Hook
re c ommend the use of high
performance manganese bat-
teri es for the greatest operat-
ing time .
Note:
---------
Do not install NiCd batteries and
att e mpt to charge them with the
supplied charger. There is no
ba tt ery protection circuit in the
ba tt ery holder.
2 -4 INSTALLING THE BATTERY PACK
Align the grooves in the bat-
tery pack with the trans- Release button
ceiver and slide the pack to
th e r ight until it locks in
place.
To remove the battery pack
push up on
the release button
and slide the pack to the left.

2-5 BATTERY VOLTAGE LEVEL METER
The S meter indicates the relative battery voltage during
transmit.
Recharge/replace the batteries when the level reaches the
low indicator.
NiCd Battery pack
MODEL V mAh Fully charged Fully discharged
PB·5
~
...... . "~ .... ~~
..•
PS-6
01
..
7.2 600
........ :-;:-;~
••••
-.- ..
PB~9 .
PB -7
r;-;oo
P8 -8 12
600
..........-
........ :::::: .
..
Manganese or Alkaline battenes (ApprOXimate battery con
dition) -
New batteries
BT -S, 9 V
•••••••• [::u~
2-6 OPERATING TIME
TH-25 series
Batt vohage IVI
Transmitting •.
Receiving .
AFOU1PUT ..
Need to replace
...... :.:::;:::~-::
....................... 1 minute
3 minutes
0 .2 W/8 0
14 NiCd battery 12\1
I\, SOOmAh IPB-BI
,,1 '
• Battery voltage is measured 81 transmis-
sion (Hi).
10
NiCd battery 7.2\1
8 ~~", §''?-='''':-t~ 1 ~Ioo=m=A=h:..c.IP~ .. ~7~I_,
6 ., ••• ':\'-=..~~, '\
lower ~mjt voltage range
for transmissiOn
4 1
,1 '••••/.... r 'J;;,;,~;;.~ b'''~
--....
\ ( low - Power ) 18T 6)
N,Cd battery 7 2V 600mAh IPS-51
Manganese battery ( 8T 6)
Alkaline manganese
battery \8T-6)
L
!N~;C~d~b.~'~'.~~~7.~2~v~2~OO2?m~A~h~I~P~8·r5~' ____ ~~ ____ ~~ __ -:~
60 120 180 240 300 360 (minu18$)
TH-45 series
Batt Voltage (V)
TransmIttIng .............................. 1 minute
Receiving ............................... 3 minutes
AF OUTPUT .............. . ...... .. 0.2 W/8 0
'4 NoCd battery 12V
600mAh IPB-B)
• Battery vonaga is measured at transmis-
SIOn (Hi) ,
"
10
8
6
4
NiCd battery 7.2V
1100mAh (Pe-7) lower limrt voltage range
for transmIssion
...... _._ ~AA Allr;eIihe manganese
/
'-1' r'" -.,.- --' - ,,,,..., '8T·S'
Manganese battery (Low'Power) IBT-6)
N,Cd battery 7
2V 800mAh IPS-s)
Manganese battery (8T 6)
N, Cd battery 7.2V 200mAh IPS-5)
60 120 180
240
300 (minutes)
lH·55 series Transm'tling
.............................. 1 minute
B
att vohage IV)
Receiving ·................................3 mil'll1t8S
14
12
10
8
6
4
NiCd
banery 12V
600mAh IPB ·B )
NiCd battery
72V 200mAh
IPS-51
'- -
AF OUTPUT.. ................... 0.2 W/B 0
• Banery voltage is measured al transmis-
sion IHi).
NiCd battery
7.2V 600mAn IPS-6)
NiCd battery 7.2V
11DOmAh IPS-7)
-:----
'.
lower ~mit voltage range for transmission
e- ~~-.~--~-=====~===-=== __ ~~
Manganese Manganese battery AA Alkeline manganese
ba ttery IST-61 (Low 'P ower) IBT-61 battery (BT.6)
60
120 18 0 240
300 Iminutes)
We r ecommend use of the NiCd battery pack. for long
tran smission or extended operation.
Man ganese battery (except Alkaline manganese battery) is
available for Low position. 7

3. OPERATION
3-1 OPERATING CONTROLS
CD Antenna connector
Connect the antenna that is supplied to this jack. Twist
to lock.
® TX indicator
ON whenever the transceiver is in the transmit mode.
®Volume 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 volume.
@SOL control
This control is used to select the desired Squelch
threshold level.
@MHz key
This key is used to select the tuning rate of the Tuning
control. When the MHz indicator is lit, the Tuning con-
trol will cause the transceiver to increase or decrease
in 1 MHz step.
®VFO key
8
This key is used to switch back to VFO operation after
operating in the MR (Memory Recall) mode. The tuning
control will increase or decrease frequency in accor-
dance
with the VFO indicator. See the chart below for
your transceiver. (kHz)
Pressing this key for longer than second will initiate
the Band Scan function.
(j) MR key
This key is used to switch from the VFO mode to the
MR (
Memory Recall) mode. The tuning control may be
used to select the desired memory channel in this
mode.
Pre ssing this key for longer than 1 second will initiate
the
Memory Scan function.
® Tuning control
Rotate this control clockwise to increase frequency
and counterclockwise
to decrease the transmit /receive
frequency.
This control is also used
to select the desired memory
channel and the scan direction.
® Tone Alert key
This key is used to activate the Tone Alert function .
®Tone key
u.s. version: This key is used to activate the
subaudible tone encoder.
European version: This key is used to transmit a Tone
signal. When the key is depressed
the repeater control signal of
'750 Hz is activated .
U.K. version: This key is used
to activate the
'750 Hz tone burst.

LCD display
(jJ) EI + (European version: EI _)
Displays the selected transmitter offset direction.
When neither indicator is
ON the transceiver is in the
Simplex mode. When both indicators are ON the
transceiver is in the Split Channel mode.
When a indicator flashes the transceiver is in the
Reverse
function.
@ Frequency display
Di splays the operating frequency to the nearest kHz.
TH-55AT/55E: Displays the operating frequency from
10 MHz digit. r aBBBB
L ______ ~- _______ 1
(jji Busy indicator
ON whenever there is a Signal present strong enough
to open the squelch. or when the squelch is not ac-
tivated. and the CTCSS key is OFF.
@ ••••••••••-
Used to indicate the relative receive signal strength, or
as an indication
of the battery voltage level during
transmit.
@ MHz indicator
This indicator flashes during MHz tuning steps.
@ MHz dot
This indicator flashes during scan operations.
@ VFO indicator
This indicator lights during VFO operation.
@ Hz dot
This indicator lights during cress frequency selec-
ti on, and is used to show the 1 Hz digit.
TH-55AT/55E: Additionally ON when the Battery
Saver and Automatic Power Off function have been
cancelled.
(jji 5 kHz tuning step indicator
This indicator lights during VFO operation when tuning
in 5 kHz steps.
@ 500 Hz dot (TH-25E/TH-45E only)
This indicator show 500 Hz.
@ T indicator
This indicator is ON when the Tone function is active.
@ CTCSS indicator
This indicator is ON when the CTeSS function is ac-
ti ve. ...(1
@ T. ALT indicator ~
This indicator is ON when the Tone alert system is ac-
ti ve. The indicator will flash when a signal is received.
@ Memory channel indicator
This indicator is used to show the selected memory
channel number.
@ Memory indicator
This indicator lights during Memory Recall mode, and
fl ashes during Memory entry.
9

@ !
KENWOOD
nl "~'"
® @
@ @
@
430MHz FM TRAN SC [IV {A
TH· 45A
@ MONITOR switch
When operating in the CTCSS (Tone Squelch) mode
you can use this key to determine if the frequency is in
use
before transmitting. Pressing this key will disable
the CTCSS function as long as the key is held depress-
ed.
® lamp switch
This switch is used to control the night lamp on the
LCD display. The lamp will turn itself OFF automatical-
ly 5 seconds after the last key operation.
@ PTT (Push To Talk) switch
Press this switch whenever you wish to transmit.
10
TH-45AT
GI GI
®l Release button
Press this button up to
release the battery pack.
@ F. Lock key
This key will deactivate
all functions except the
Lamp, MONI, PTT func ·
tions.
@ Speaker
@ Microphone
@ Battery case
@ SP jack
This jack is used to con-
nect an external speaker
or earphone. The recom-
mended impedance is
8 n.
@ MICjack
This jack is used for con-
nection of an external
microphone. The use of
an electret type micro-
phone is recommended.
Input impedance is 2 kG and the DC voltage on this ter-
minal is Approx. 4 V (MAX 3.5 mA).
Not.: ---- ________________________________ __ __
The use of a dynamic microphone is not recommended.
Speaker ,
,
..
SP
V
~
'"
¢2 .5
Ground Plug x
w
,!;
,
5V
, u
,
5V
M~C
V ~
. ~
!
~
•
MIC
1=
II
~
PIT PIT , +
10
::;
,
, x
w

•
~
u 4
KE NWOOO
TH · 55AT
TH· 45A TH · 55AT
@ DTMF PAD (with the TH-25AT/45AT/55AT)
This key pad is used in conjunction with a repeater to
provide AUTO PATCH capabilities.
@ M (Memory) key
This key is used to enter a frequency, offset, etc. into
the desired Memory channel..
When this key is pressed during Memory channel
operation
the contents of the Memory channel are
duplicated in the VFO, and
the transceiver returnes to
VFO operation. .
The
contents of the memory are not lost during this
procedure.
@ CTCSS key
This key is used to select the CTCSS (Tone squelch)
f
unction.
I3l SHIFT key
This key is used to select the desired transmitter offset
for repeater operation. When the offset function is ON,
+ or Gi3 will be displayed in the display.
@ REV key
Pressing the REV key allows you to reverse the
transmit/receive frequencies
dur ing repeater opera-
ti ons. This will allow you to check the input of the
repeater
or to operate on a reverse repeater pair.
® HI-LO switch
This switch is used to select the transmit output
p ower .
T
H·25A/45A SERIES
TH-55AT SERIES
(II)
HI La
(II)
LO HI
@ RIT control (TH-55AT/55E only)
When the transmit frequency of the distant station
d
rifts a little bit during the OSO, but you do not wish to
a lter your transmit frequency to compensate, you may
wish to make use of the RIT control function. This con-
tr ol allows shifting the receive frequency apploximate-
Iy ± 5 kHz without shifting the transmit frequency.
11

3-2 RECEIVER OPERATION
Connect the battery pack, and the supplied antenna.
Set the controls as follows:
1. Rotate the POWER (VOLI control clockwise to turn the
transceiver
ON . A frequency will appear in the display.
2.
As the VOL control is rotated clockwise either
background noise or a aso will be heard coming
from
the speaker. provided the CTCSS and Squelch are not
ON.
3. To eliminate the no signal noise turn the SOL control
clockwise to the point the background noise just disap-
pears. This
point is known as the Squelch Threshold
point.
4. Select the desired operating frequency using the tuning
control.
Frequency Selection
Press the VFO key. An operating frequency will appear in
the display.
• VFO
Mode
1. Press the VFO key.
2. Turn the tuning control to increase/decrease the fre-
quency. The step size is determined by the location of
the VFO indicators (See Step Size Selection below).
•
MHz Mode
1. Press the MHz key. The MHz indicator will begin
flashing.
2. The tuning control will now increase/decrease the
operating frequency in 1 MHz increments.
3. The tuning step will revert to the VFO mode 5 seconds
after you stop turning the tuning control.
12
Step Size Selection
1. Press the VFO key .
2. Pr ess the M key.
3. Within 5 seconds
of pressing the M key press the MHz
ke y. The VFO indicator will toggle between 5 kHz and
10 kHz (See the chart below for your transceiver.) each
time
th is sequence is performed. I
kHz l
Not . :-- -- -------- -- ---- ------ ---- -------------
If you are al ready in the V FO mo de y ou can skip s tep number 1.
3-3 TRANSMITTER OPERATION
CA UTION: --------------------- --- -------------------
Ensu re that an antenna with a low standing wave ratio
(SWR) is attached to the antenna connector before attemp-
ting to transmit . Failure to provide proper termination may
result in damage to the final amplifier section.
Always check to ensure the frequency is clear before
transmitting .
, . Select
the desired operating frequency using any of the
methods described above.
2. Check the frequency
to see if it is occupied before you
tr ansmit. If you are using CTCSS (Tone Squelch) press
the MONITOR key
to allow the Squelch to open.
3. Press the PTT
switch. The TX indicator will light .
4. Speak into the microphone. The recommended distance
to the microphone is 5 em (2 inches). Talking closer
m
ay result in overdeviation of your transmit signal, and
ta lking too far away may result in reports of weak audio.
5. Release
the PTT switch to return to the receive mode.
The
TX indicator should go out.

3-4 MEMORY
The transceiver provides 14 memory channels. In addition
to serving as a normal memory channel some of the
memory channels serve a dual purpose to specify other
parameters.
.. Memory channel 13 and 14 are used to store both a
transmit and a re ceive frequency for ODD sPLIr
operations.
• Memory channel contents
Each memory channel is capable of storing;
.. Frequency * cress status
.. Tone status (Excluding European Versions)
.. Tone frequency .. SHIFT status
3-4-1 AUTOMATIC MEMORY INITIALIZATION
CAUTION:
~--:::-- ______ ____ _
This procedure will erase all of the current data in memory
channels 1 thru 1 O.
This transceiver can automatically store data in memory
channels 1 thru lOin the following steps.
TH- 25A / 25AT TH-25E TH-45A145AT/45E155AT/ 55E
MR key
VFO ke
15 kHz
20 kHz 12.5 kHz
25 kHz 25
kHz
This automatic storage will begin from the frequency that
appeared in the display before the transceiver was turned
OFF.
1. Press and hold either the
MR or the VFO key and
turn ON the power .
2. Release the MR or the
VFO key. The memory
channel 1 indicator will be
on.
3. Rotate the tuning control
to confirm data entry in
the remaining channels (2
thru 10).
DO
MR or VFO
and Power ON
IIJ U '-'rIrI I
., -'.UUU •
3-4 -2 MEMORY ENTRY
1. Select the desired opera-
ting frequency, offset,
tone frequency. etc. (For
example 145.600 MH z)
2. Press the M key to select
the Memory Entry Mode .
3. Within 5 seconds of press-
ing the M key rotate the
tuning control until the
desired memory channel
number appears in the
display. (For example Ch.
12)
4. Press the MR key within 5
seconds
of selecting the
Memory channel number.
If you do not press the MR
key within 5 seconds data
will not be stored into
memory.
o
VFO
Flashes
IUS C rlrI",
., .OUU.,:
Flashes
o
MR
13

3-4-3 .MEMORY SHIFT
It is possible to copy the contents of a memory channel to
the VFO without erasing the memory channel.
1. Select
the desired Memory
Channel. (For example Ch.
12)
2. Press the M key.
3. Within 5 seconds press
the VFO key to copy the
data .
3-4-4 MEMORY RECALL
1. Press the MR key. The
memory channel that was
active before return to the
VFO mode will appear in
the display. (For example
Ch. 12)
2. Rotate the tuning control
until the desired Memory
channel number appears
in
the display. (For exam-
ple Ch. 5)
Not.: --------
If a channel contains no data
it cannot be displayed using
this procedure.
3. To return to the VFO
mode, press the VFO key.
14
,,,e cnrl,",
• -',Joa ... UJ II:
~
M
o
V FO
",eCriri
• '';''oOUU
o
MR
1tJ'~ J:. rI" , "'
• '..JoyUU.,;,
55
""
:'-1 0 uu 5
3-4-5 ODD SPLIT
Memory channels 13 and 14 store both a transmit and a
receive frequency. These channels
allow operation on
"O dd Split" repeater channels.
• Data entry
1. Select the desired receiver
frequency, tone frequen-
cy, and tone status. (For
example
145.080 MHz)
2. E nter the data into either
m emory channel 13 or 14
as described previously.
(For example Ch. 13)
3. Select the desired trans-
mitter frequency by press-
ing the VFO key and then
rotating the tuning control.
( For example 145 . 300
MHz)
4. Press the M key . Memory
channel 13 will appear in
the display.
It., C =l
rI
"
• -..,Jo..JUU
IU'~ riB",",
• '..JoU u.:,
Flashes

5. Press and hold the PTT
key.
6. Press the MR key and then
release both keys.
Note: ---- ____ _
The PTr switch will not initiate
transmit during this operation .
The ~ and + indicators
will be on to indicate that this
memory channel now contains
odd split frequency data.
• Release
PTT switch
and
Q
o
MR
PTT switch
••••••••••
:r
0 cancel
this Odd Split data simply store a new frequency
Into the memory channel using the normal memory channel
method.
Note: ---:-----:- _____________ _
• Only the receiver frequency will be transferred to the VFO during
a
Memory Shift operation.
·TH · 45A / 45AT / 55AT : During Odd Split operation the SHIFT key
does
not work .
3-4 -6 MEMORY CHANNEL LOCKOUT
The Memory Channel Lockout function allows you to tem-
pora ri ly skip unwanted Memory Channels except Channel 1.
1. Press the MR key and
sel ect the memory chan-
nel you
wish to skip. (For
example Ch. 13)
2. P re ss the M key for longer
than 1 second. Both the
channel number and the
Me mory indicator (.A.) will
fl ash.
3. P re ss the MR key within 5
s ec onds. The selected
me mory channel number
will disappear and the
channel number of the
n ex t active memory chan-
nel will appear. (For exam-
ple Ch. 1)
• Release
1. P re ss the MR key to select
th e MR mode.
2. Press
the M key for longer
th an 1 second. Both the
channel number and the
Me mory indicator (...) will
flash.
[0 for longer
than 1 second
M
o Flash
MR
[0 for longer
th an 1 sec ond
M
I
,
IUunnn I
'"l '.UUU Tl
Flash
15

3. Select the desired channel
number using
the tuning
control. You will be able to
see all channel numbers
with this procedure. (For
example Ch.
13)
4. Press the MR key within 5
seconds. The Memory
channel number will ap·
pear in the display.
3-4-7 CLEARING ALL MEMORY (Microprocessor
initialization)
To erase the data from all memory channels at the same
time you can reset the microprocessor. This will remove
any programmed information that you have entered.
1. Turn
the Power switch OFF.
2. Press and hold the M key.
3. Turn ON the power switch and then release the M key.
4. The display will
show: 144.000 ( TH-25A / 25AT /25E)
430.000 (TH-45A /45E)
440.000 (TH-45AT)
60.000 ( TH-55AT /55E)
3-4-8 MEMORY BACK-UP BATTERY
A lithium
battery is contained in the transceiver to retain
memory. Turning off the power switch, changing or fully
discharging the normal battery will not erase the memory .
The
battery should last for approx. 5 years. When the bat-
tery discharges, an erroneous display may appear in the
display. (For the lithium battery replacement, refer to IN
CASE
OF DIFFICULTY. Page 23)
16
3-5 SCAN
For proper scan operation the squelch must be adjusted to
the threshold point .
Th e MHz dot will flash ON and OFF as a visual indication
that the transceiver is scanning.
• Scan Modes
Band Scan: Scans the entire band.
Pressing
the VFO key for longer than 1 se-
cond
will initiate Scan. The scan step size
depends upon
the current step programming.
Me m ory Channel Scan: Scans those memories that ac-
tually have data and have not been locked
out.
• Scan Hold
Pressing the MR key for longer than 1 second
will initiate Scan.
Scan
will stop on a busy channel and hold for approximate-
ly 5 seconds. Scan will resume even if the station is still
pre
se nt . You can manually cause scan to resume by
rot ating the Tuning control.
• Scan Direction
Scan will begin in an upwards direction. You can reverse
the direction
by rotating the Tuning control counter-
clo
ck wise.
• Scan Release
Scan can be released by pressing PTT switch (no transmit -
ting ) or any key except the LAMP, or MONI key.

3-6 REPEATER OPERATION
3-6-1 TRANSMITTER O FF S ET S
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:
I ~
TH - 25A
TH-45E
TH-
25AT
TH- 45A
European U.k. TH- 55AT TH-SSE
TH-25E
TH - 4SAT
. .....,.,
. ..-
+
+600 kHl +S MHz +1.6MHz +12MHz + 36MHz
[3 -600kHz -5MHz -1.6MHz - 1. 6MHz - 12MHz
-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 ~
( [3 to ~ with TH-45E European version) to no offset
(simplex).
The transceiver allows you to store the frequency, offset in
memory, or you can select these functions directly from the
keyboard.
• Aut o-O ffset (TH-25AT only)
The
TH-25AT 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.
144 .00 145 . 10 146 .00 146.60
147 . 40
148 .00
51
5 I 5
1+151 1+151
i5
I I I
S: Simplex Channel
145.50 146.40 147.00
147 .60
3-6 -2 REVERSE FUNCTION
Some repeaters utilize a " Reverse pair
", i.e. the trans-
mi t/r eceive frequencies are exactly the reverse of another
rep
ea ter. For example repeater A uses 146.000 for a
trans
mit frequency (OUTPUT) and 146 . 600 for receive
(INPUT). Repeater 8 uses 146.000 for its receive and
14 6. 600 for its transmit frequency. It would be inconve-
nient
to have to reprogram the transceiver each time if you
wer e in range of both repeaters.
Th e REV key allows you to reverse the transmit and receive
frequencies.
To use the REVERSE function press the REV
key. The offset indicator ( + or [3 I [3 or (3) will
flash OFF and ON in the display to remind you thai"You are
wor king a reverse repeater pair.
To re ~ur". to normal offsets press the REV key again. This
fun ctton IS also useful to check the input frequency of the
rep
ea ter, so that you can determine if you are within
SIMPLEX communications range.
3-6 -3 TONE OPERAn ON
Some repeaters require
the use of a control signal to activate
the repeater. Several versions are currently in use
wor ldwise.
In the United States sub-audible tones are sometimes used.
Wit h the TH-25A / 25AT / 45A / 45AT / 55AT 37 different sub-
audible tone frequency selections are possible with the use
of the optional sub-audible tone encoder/decoder (TSU-61.
This accessory also allows
for CTCSS (Tone Squelch) opera-
tion s. When this option is activated the squelch of the
tran sceiver will only open when the proper sub -a udible tone
is received.
, 17

• Tone Activation
To activate the TONE function depress the TONE switch on
the
top of the transceiver. The tone indicator will appear in
the display
to signify the tone has been activated. To turn
the tone OFF press the TONE key again.
Tone frequency selection
1. Press the CTCSS key for Tone Frequency
longer than 1 second.
The current tone fre-
Quency
will be dis-
played.
2. Rotate
the Tuning con-
trol until the desired
tone frequency appears
in
the display.
3. Press the TONE key
to
turn to the normal fre-
quency display.
4. If CTCSS (Tone Sque-
87.0 Hz
71.9 Hz
74.4 Hz
77 .0 Hz
79 .7 Hz
82 .5 Hz
85 .4 Hz
88.5 Hz
91 .5 Hz
94 .8 Hz
1 00.0 Hz
103 .5 Hz
107 .2 Hz
110 .9 Hz 173.8 Hz
114 .8 Hz
179 .9 Hz
1 18 .8 Hz 186 .2 Hz
123 .0 Hz
192 .8 Hz
12 7.3 Hz
203 .5 Hz
131.8 Hz
210.7 Hz
136 .5 Hz
218.1 Hz
141.3 Hz
225.7 Hz
148 .2 Hz
233 .6 Hz
151 .4 Hz
241.8 Hz
156 .7 Hz
250 .3 Hz
162 .2 Hz
167 .9 Hz
lch) is not desired press the CTCSS key to cancel the
function. The transmit tone will still be active.
Note: -------------------------------------- -- ---
When no Tone Unit is installed, pressing the TONE key will not
transmit a subtone, even
if the indicator is ON .
In Europe a 1750 Hz tone is used in transmit. Press and
hold the TONE key to transmit the access tone, then press
the PTT switch.
In the United Kingdom a 1750 Hz tone burst at the beginn-
ing
of each transmission is used. Press the Tone key.
Since use of this tone is required in the Europe and the
United Kingdom, an 1750 Hz tone encoder is encluded as
standard equipment.
18
• CTCSS (Tone Squelch) Operation
1. To
actuate the CTCSS (tone squelch) function (decode)
select the desired tone frequency as described above
but do
not press the CTeSS key the second time.
2. Squelch
will now open only when the transceiver
receives
the same subtone frequency. .
3. To release tone squelch operation press the CTeSS key.
The CTCSS indicator should go
out.
It is a good operating practice to check the frequency
before
transmitting. A MONITOR switch has been provided
for this purpose when using the CTeSS (tone squelch)
func tion. Pressing this switch will open the squelch so you
can check
for activity.
• TSU-6 (option) Installation
1. Remove
the backing from
the cushion (large) that
was provided the TSU-6
and
attach it to the back
of
the TSU- 6.
2. Re move the Battery Pack
and
remove the four
phillips head screws from
the terminal plate of the
transceiver.
3. Turn the terminal plate
over and take out the
cable as shown in the
diagram.
4. Remove the clear tube
c
ove ring the connector,
and
the resistor inserted
in
to the connector.
W
Terminal plate I
5. A ttach the cable from TSU-6 as shown in the diagram.
6. Remove the backing
from the other side of the cushion
and
attach the TSU-6 to the transceiver.

7. Push up on the release button and set the terminal plate
in the hole
of the release button. Replace the terminal
plate and
tighten the screws to complete the installa-
tion. Do not pinch the wiring when closing the terminal
plate.
3-6-4 AUTOPATCH
. (TH-25AT/ 45AT / 55AT U. S.A . version only)
Some repeaters
offer a service known as autopatch . This
allows you to dial a telephone number from your
tran sceiver and carry out a telephone conversation, much
like a car telephone, or cellular telephone. This function re -
quires
the use of a DTMF (Dual Tone Multi Frequency) pad.
In addition to the normal 12 keys that are found on your
telephone the transceiver also provides 4 additional keys,
A. S, C. and D. These keys are required
by some repeater
systems for various control functions. You should check
with the control operator of your repeater to determine if
their use is required. A chart is provided that lists the tones
that are generated when you press each ke y.
1. To activate the DTMF pad, press and hold the PTT
switch.
2. Now press the keys just as you would dial a telephone.
Note : ---------
Some re peat ers will require a
special sequence of keys to ac-
ti v at e the Autopatch . Again
you should check with the con-
tr ol o perator of your repeater
for thi s sequence.
Audio tones
I~
12 09
697 1
770
4
B52 7
941
•
1 336
2
5
8
0
( Hz )
1 477 1633
3 A
6 B
9 C
• 0
3- 7 BEEP TONE
If you would like audio confirmation when a function is ac-
tiva te d press the M and then the T. AL T key. The
tran sceiver will then supply audio confirmation according
to the chart below. Pressing the same combination again
will turn the
function OFF.
Key operation
A 4
40.00 REV, T.ALT, TO NE , CT ess, MHz. M, SC AN
GI
19

3-8 TONE ALERT SYSTEM
The Tone Alert function will provide an audible "ala rm" to
signal when someone is transmitting on the frequency you
are monitoring.
For proper
tone alert system operation the squelch must be
set to the threshold point.
, . Press the T. ALT key. The T.ALT indicator will light .
2. When a signal is present:
The T.
ALT indicator will flash.
The busy indicator will light.
The transceiver will beep ON and OFF for about 5
seconds.
3. The T.A Ll function can be released by pressing the
T. AL T key again.
Note :---------------- ---- ------ ---- -- -------- ---
• The tuning control, PTT switch. and all the keys except MONI,
LAMP are not effective during the T .AL T operations.
• Turning on the power switch while the T.ALT function is on
may cause the
BELL indicator to flicker.
If this happens, turn the T.A LT off, and then back on.
3-9 SA ITERY SAVER
The transceiver provides a battery saver mode to conserve
on
battery power .
The transceiver
will activate the battery saver circuit 10
seconds after the last key operation with the squelch clos-
ed.
• I
20
ON
Approx.
200 mS
OFF
ON
OFF
• I
Approx. 800 mS
Th e function will be released by key operation or when
squelch opens.
The
function cannot operate during scan or tone frequency
selection.
Not e :-- ---- ---------- -- ---------- -- -------------
It is possible that you might press the MONI switch during the OFF
period. Squelch would not open during this period.
3-10 AUTOMATIC POWER OFF
Th e transceiver also provides an Automatic Power OFF cir-
cuit.
The circuit action is described
belo, ; w". '- ____________ __ ,
1. A 5 second audio confir-
mation alert
will sound
after 59 minutes if no
signal has been received
and
if you have not per-
formed any key operation.
(/1-'
'U
2. 1 minute after this alert signal the transceiver Will shut
i
ts elf OFF except for enough power to show "po OFF"
in the LCD display.
Rel ea se
Th e f unct ion can be released by pressing the MONI key or
turning
the Power switch OFF and back ON .
Th e function can not be activated during scan or Tone Alert
System operation.
No te :---- -- ---- -- ---------- -- -------------------
To conserve battery life even more simply turn the transceiver
OFF when you are not using it.

3-11 BATTERY SAVER and AUTOMATIC
POWER OFF function CANCEL
(TH-55AT/55E only)
1. Turn the Power switch OFF.
2. Press and hold the MHz key.
3. Turn on
the Power switch and then release the MHz key.
4. The Hz dot will light as a
,visual reminder that the
Battery Saver and Auto·
matic Power OFF function
have been cancelled.
Hz dot
The function can be restored by this same procedure. The
function cannot be activated during Tone Alert System
operation, or when F.LOCK is ON.
21