TM-255 SCHEMATICS (PDF)


Kenwood Corporation
All-Mode Transceiver  TM-255/455(A/E)

All-mode versatility enters a new era with our innovative TM-255A/E (2 m) and TM-455A/E (70 cm), both featuring a detachable front panel for easy mounting in a car. But whether mobile or stationary, these compact transceivers offer matchless performance -- in FM, SSB and CW modes. Among their many impressive features are 101 memory channels, DDS with "fuzzy logic" control, twin tuning dials, and a data connector for 1200/9600 bps packet communications.

Features at a glance:

2 m (TM-255A/E) or 70 cm (TM-455A/E) all-mode operation
101 memory channels
DDS with "fuzzy logic" control
TF-SET (TX frequency set) function
DTSS selective calling with pager function
1200/9600 bps packet terminal

TM-255/455(A/E) in detail:

40-watt output
Maximum RF output is 40 watts (TM-255A/E), and 35 watts (TM-455A/E). A HI/LO switch enables power reduction to 5 watts.

100 multi-function memory channels plus 1 call channel
Facilitating on-the-move operation are 101 memory channels, plus memory shift and memory scroll functions. Channels 50~98 are capable of storing transmit and receive frequencies independently.

Multi-scan functions
There is a choice of full band and programme band scans, memory scan with memory channel lock-out, MHz scan and V/M/C scan. The operator can also select time-operated or carrier-operated scan stop modes, and adjust scan speed.

Data connector for 1200/9600 bps packet
A 6-pin mini DIN connector lets the operator enjoy either standard 1200 bps or 9600 bps high-speed packet communications with a TNC.

DDS (Direct Digital Synthesizer) with fuzzy control
We've incorporated "fuzzy logic" control circuitry, so the main encoder tunes smoothly from fine (5 Hz step) to fast forward (200 Hz step).

Twin tuning dials
In addition to the smooth-action dial on the main unit, there is a click-type dial on the detachable panel for convenient mobile use.

Dual-menu system
The user-friendly menus -- which are also accessible via the supplied microphone -- are divided into two groups (A & B) depending on frequency of use.

Interference reduction
AIP (Advanced Intercept Point) circuitry allows the operator to choose either high sensitivity or a high intercept point to suit conditions. IF-SHIFT (SSB, CW) and a pulse noise blanker further improve RX performance.

TF-SET is available when the receive frequency is locked, so the operator can avoid losing a targeted station.

Multi-function microphone
The supplied remote-control microphone has 4 programmable function keys -- ideal for mobile operation.

Other Features:

Built-in DTSS selective calling with pager
Semi break-in circuit (CW)
Automatic mic gain control circuit (SSB)
Built-in TCXO (temperature-compensated crystal oscillator)
Tone alert system with elapsed time indicator
S-meter squelch
All-mode squelch
Built-in CTCSS encoder & optional decoder (TSU-8)
Auto power-off & time-out timer

Dimensions (W x H x D)

180 x 60 x 215.5 mm (7.0 x 2.4 x 8.5 in.

Please note that not all features and options may be available for the model sold in your region.
Operation of DTSS, Pager, DTMF, and CTCSS is subject to local regulations.

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Updated 98/07/01 (C) 2001 Kenwood Corporation