Kenwood TM 255 A Owners Manual

Page 2

Models Covered by this Manual:

- TM-255A: 144 MHz All Mode Transceiver
(U.S.A./ Canada/ General)

. TM-255E: 144 MHz All Mode Transceiver
(Europe)

TM-455A: 430 MHz All Mode Transceiver
(U.S.A./ Canada)

. TM-4SSE: 430 MHz All Mode Transceiver
(Europe)

Notice to the user:

One or more at the following statements may be
applicable to this equipment.

FCC WARNING

This equipment generates or uses radio frequency energy.
Changes or modifications to this equipment may cause harmful
interference unless the modifications are expressly approved in
the instruction manual. The user could lose the authority to
operate this equipment if an unauthorized change or modification
is made.

INFORMATION TO THE DIGITAL DEVICE USER REQUIRED
BY THE FCC

This equipment has been tested and lound to comply wim the
limits fora Class B digital device, pursuant to Part 15 cf the FCC
Rules. These limits are designed to provide reasonable
protection againstharmtul interference in a residential installation.

This equipment generates, uses and can generate radio
frequency energy and. if not installed and used in accordance
with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that the
interference will not occur in a particular installation. If this
equtprnent does cause harmful interference to radio or television
reception, which can be determined by turning the equipment of!
and on. the user is encouraged to try to correct the intefierence
by one or more of the lot/owing measures:

. Heorient or relocate the receian antenna
. increase the separation between the equipment and receiver.

' Connect the equipment to an outlet on a circuit diltereht from
that to which the receiver is connected.

- Consult the dealer [or technical assistance.

Page 9

Fuse
(15A)

DC POWER CABLE CONNECTION

Route the DC power cable directly to the vehicles
battery terminals using the shortest path from the
transceiver. It is not recommended to use the
cigarette lighter socket since some cigarette lighter
sockets introduce an unacceptable voltage drop.

To prevent the risk of short circuits, disconnect other
wiring from the negative (-) battery terminal before
connecting the transceiver. Confirm the correct
polarity of the connections before attaching the power
cable; red connects to the positive (+) terminal, black
connects to the negative (-) terminal. Use the lull
length of the cable without cutting off the excess even
if the cable is longer than required. In particular,
never remove the fuse holder from the cable. After
completing transceiver connections to the battery,
then reconnect any wiring removed from the negative
terminal.

iii IIIIHU

9&3 Fuses (20A) 2

To Antenna

Ground

*Red
Black
9 @
S aker
12Vbattery pe

If the power cable must be routed through a hole in
the vehicle chassis or body. for example in the firewall
at the front of the passenger compartment, use a
rubber grommet to protect the cable from abrasion.
The entire length of the cable must be dressed so it is
isolated from heat and moisture. After the cable is in
place, wind heat-resistant tape around the fuse holder
to protect it from moisture. Tie down the full run of
cable.

The vehicle battery must have a nominal rating of
12 V. Never connect the transceiver to a 24 V
battery. Be sure to use a 12 V vehicle battery that
has sufficient current capacity. If the current to the
transceiver is insufficient, the Display may darken
during transmission (at audio peaks during 888
operation), or transmitter output power may drop
excessively.

Note:

0 It you use the transceiver tor a long period when the vehicle
battery has not been fully charged, or when the engine has
been stopped, the battery may become discharged, and will not
have sufficient reserves to start the vehicle Avoid using the
transceiver under these conditions.

o Replace blown [uses only after investigating and correcting the
cause or the tailed luse. Always replace a blown luse by a new
fuse with the specified ratings.

I Replacing Fuses

If the fuse blows determine the cause then correct
the problem After the problem IS resolved, only
then replace the fuse. If newly Installed fuses
continue to blow, disconnect the power plug and
contact your dealer or nearest Service Center for
assistance.

Function Fuse Current
Transceiver Power Cable 15 A
DC Power Cable » 20 A

CAUTION: Only use fuses ol the specified type and rating.

ANTENNA CONNECTION

Before operating mobile, you must first install an
efficient, well mobile installation will depend largely on the type of
antenna and its correct installation. The transceiver
can give excellent results if the antenna system and
its installation is given careful attention.

Your choice of 144 MHz or 430 MHz antenna should
have a 50 ohm impedance to match the transceiver
input impedance. Use low-loss coaxial feed line that
also has a characteristic impedance of 50 ohms.
Coupling the antenna to the transceiver via feed line
having an impedance other than 50 ohms reduces the
efficiency of the antenna system, and can cause
interference to nearby broadcast television and radio
receivers.

CAUTION: Transmitting without an antenna or other matched

load connected may damage the transceiver. Always connect the
antenna to the transceiver firstbelore transmitting.

GROUND CONNECTION

The ground, which is the other half of the antenna
system, is very important when using most mobile
antennas. Connect the feed line ground for the
antenna securely to the vehicle's chassis, and be
certain to bond (electrically connect) the vehicle body
to the chassis. The sheet metal will provide the
primary ground plane, so be sure to establish a good
RF connection from the feed line to both the chassis
and the body. For comprehensive information on
mobile antennas and their successful installation and
optimization, refer to any of the publications on the
subject available at dealers handling Amateur
supplies.

If your car has plastic bumpers, make sure to ground
the antenna mount to the body and the chassis of the
car.

Page 12

KEY 0R ELECTRONIC KEYER

For CW operation. connect your key or electronic
keyer to the KEY jack on the rear panel. Use a 3.5
mm diameter mono (2»conductor) plug. When using
an electronic keyer, ensure the keyer wiring polarity is
correct.

+5V
y Contact current approximately 1 mA

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iii

GND GND +
PACKET EQUIPMENT

If you intend to use this transceiver for Packet
operation, you will need the following equipment:

Personal computer with communications software
(Alternatively, a "dumb" terminal capable of
sending ASCII commands)

- TNC (Terminal Node Controller)
- TNC power supply
- RS-2320 cable
6-pin mini DIN plug and cable (optional PG-5A)

Refer to the accompanying diagram and the
associated hardware instruction manuals to configure
the equipment as shown. Connect your TNC to the
DATA connector on the transceiver Rear Panel using
a cable equipped with a 6-pin mini DIN plug. You can
use the microphone connector on the Front Panel;
however, the DATA connector is recommended for
the following reasons:

- The DATA connector uses connections at different
modulation/demodulation points depending on the
transmission speed selected via Menu B, No. 77
{page 22). Therefore, using the DATA connector
will give optimum performance especially if using
9600 bps.

~ Using a mini DIN plug with a good-quality shielded
cable will provide better rejection from computer
noise.

Easier to switch between voice and data modes.
No cable changes necessary therefore less
chance of damaging the connectors.

Do not share a single power supply between the
transceiver and the TNC. Keep as wide a separation
between the transceiver and computeras practical to
reduce noise~pickup by the transceiver.

_1 :lNSTALLATION AND CONNECTION

Page 16

2 GETTING ACOUAINTEB

('9)

G?)

REAR PANEL
'F
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(:3 1 13.5v
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G) Power input DE 13.8 V

Connect a 13.8 V DC power source (pages 2 and 3}.
You can use either a 12 V vehicle battery or a
regulated DC power supply with the supplied DC
cable. The TM-255 draws less than 13 A and the
TM455 draws less than 15 A at full transmitter output
power.

(2) ANT

Connect an external antenna designed for operation
on the same band as this transceiver {pages 2 and 4}.
When making test transmissions, connect a dummy
load in place of the antenna. The antenna system or
load should have an impedance of 50 ohms. Accepts
a male PL-259 coaxial plug.

® KEY

Connect a key or electronic keyer for CW operation.
Accepts a 3.5 mm diameter mono (2-conductor) plug.
Always turn the transceiver power OFF before
inserting the key plug to avoid momentarily
transmitting as the plug is inserted. See page 5 for
connection details.

(9 DATA

Connect a Terminal Node Controller (TNC) for Packet
operation. Accepts a 6vpin mini DIN plug. Also can
be used to control external equipment such as a linear
amplifier. See page 5 for further details.

© EXT. SP

Connect an optional 8 9 external speaker for clearer
audio (page 4}. Connecting an external speaker cuts
off audio automatically to the internal speaker.
Accepts a 3.5 mm diameter (2-conductor) plug.

(5) GND

Connect a heavy gauge wire or copper strap between
the ground terminal and the nearest earth ground
[pages 2 and 4}. Do not connect the ground wire to
either your house electrical wiring. or gas or water
pipes. A wellvgrounded transceiver will reduce the
risk of interference to television or broadcast radio
receivers. It can also reduce receiver noise caused
by static discharges.

Page 31

SPLIT-FHEOUENCY CHA

AGE

Store a different transmit frequency and receive
frequency in any memory channel from 50 to 98 with
this procedure.

1

Select the receive frequency, modulation mode,
and other data (as required) using VFO A.

U58

Press [CLR].

- This step is optional. The purpose is to match
the VFO A and VFO B frequencies. This will
probably make selecting the VFO 8 frequency
quicker.

3 Press [N81 to select VFO B.
4 Select the transmit frequency using VFO B.

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Press [MB] to select VFO A.

- The VFO selected here contains the frequency
that will become the memory receive frequency
after completing Step 8 below. The other
VFOs frequency will become the memory
transmit frequency.

Press [MIN].
~ The last memory channel selected appears.

. Pressing [MHz] allows you to select from empty
memory channels only. Pressing [MHz] again
cancels this function.

Select a memory channel using the
Alternate Tuning control or microphone
[UP]/[DWN].

CH

Press [MJN] again.

- The data selected in Steps 1 through 5 is stored
in the selected memory channel. and the
transceiver returns to the previous mode.

Note:

9

O

Shift status and Reverse status cannot be stored in a split-
Irequency memory channel.

Pressing [MIN] overwrites new data on any previous data in
that channel.

SCA QUE
The lower and upper frequency limits for tuning in
VFO mode or for Program Scan are stored in memory

channel 99. Store these frequencies with this
procedure.

1 Select the lower frequency limit, modulation mode
and other data using VFO A.

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Press [MB] to select VFO B.
3 Select the upper frequency limit using VFO B.

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4 Press [A/B] again to select VFO A.

5 Press [M.IN].

' The last memory channel number selected
appears.

6 Select memory channel 99 using the
Alternate Tuning control or microphone
[UP]/[DWN].

7 Press [M.IN] again.

- The data selected in Steps 1 through 4 is stored
in the selected memory channel. and the
transceiver returns to VFO mode.

Nate: Pressing [MIN] overwrites new data on any previous data
in that channel.

I Programmable VFO Function

After programming a lower frequency limit and an
upper frequency limit into memory channel 99, you
can then select this channel while in Memory
Recall and use the Main Tuning control to tune
within the programmed range as if you were in
VFO mode.

To confirm the current programmed range, press
[F.LOCK]. then press microphone [UP] and
[DWN] to check the limits.

A:

5 MEMORY FEATURES

3

Page 44

AUTO MODE/AUTO OFFSET I

As explained under "AUTOMATIC MODE

; SELECTION" {page 18}, Automatic Mode allows the
transceiver to choose automatically the correct
modulation mode based on the currently selected
frequency. Although your transceiver is initially
programmed according to international agreements,
you have the capability to change this programming.
This includes changing the programming for
Automatic Transmit Offset which shifts your transmit
frequency to allow you to access voice repeaters
(page 19}.

Before beginning to reprogram, draw a simple
diagram as shown below to represent the new plan
that you want to store in the transceiver. Substitute
actual frequencies and modes in place of the
variables shown. When you have your drawing
complete, programming will take only a few minutes.

Flower F1 F2 F3 r:N= Fupper
Model Mode 2 Mode 32 ModeN

N220

Flower -» Transceiver's lower frequency limit

Mode 1 -+ First modulation mode

F1 -) First mode boundary

Mode 2 -> Second modulation mode

F2 -> Second mode boundary

Mode 3 -) Third modulation mode

F3 -> Third mode boundary

Mode N -> Nth modulation mode

FN -) Nth mode boundary

Fupper -> Transceiver's upper frequency limit

1 Press [AUTO/FM]+ POWER ON.
- Menu No. 01 appears.

MENU AVFO AUTO
u r i: n n n F!
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2 Enter the first mode boundary frequency (F1).

i, - [F.LOCK] or microphone [UP] orMain Tuning
CW -> Increments frequency

' [LOW] or microphone [DWN] or Main Tuning
CCW -> Decrements frequency

- Mode boundary frequencies must be 10 kHz or
more than the boundary stored in the previous
menu number. Menu No.01 frequency must be
10 kHz or more than the transceiver lower limit
frequency. All mode boundary frequencies
must be less than the transceivers upper
frequency limit.

l 3 Select the first mode (Mode 1) using [AUTO/FM]
or [SSE/CW].

- If $88 or CW is selected in this step, jump to
Step 5.

4 Select the transmit offset you want for this portion

of the hand using [SHIFT].

- Transmit offset can only be set if FM mode was
selected in Step 3.

5 If you have entered all the mode boundary
frequencies you want to program. jump to Step 6.
Otherwise, increment the menu number using the
Alternate Tuning control and jump to Step 2 to
enter the next mode boundary frequency, mode,
and transmit offset, when necessary.

- Menus greater than the menu number that
contains the transceivers upper frequency limit
are ignored by the transceiver.

6 Select Menu No. 00 using the Alternate Tuning
control.

IE. AWO AUTO
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7 Press [F.LOCK], [LOW], or microphone [UP] or

[DWN].

' The data is recorded. The Display shows
"good" if the data was recorded correctly
otherwise "error" appears. If "error" appears,

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2:

repeat Steps 6 and 7.
MENU A VFO AUTO
E, - - -' FM
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8 Press [CLR] to return to operating mode.

KEY CONFIRMATION BEEP TONE

The Beep Tone function provides a beep to provide
feedback each time a button is pressed . If you
prefer. this beep tone can be disabled via Menu B,
No. 50. The default is ON.

The volume of the beep level can be changed via
Menu A, No.08. The default for the volume is High
(H). This setting also affects the levels of the CW
sidetone and the V82 Voice Synthesizer option.

Note: There is an interaction between the setting of Menu A, No.
08 and the VOL control. The VOL control must be at 12 o'clock or
higher before the effect of the menu setting can be noticed.