Control unit | Kenwood TK-940 instruction

CIRCUIT DESCRIPTION

6.Control unit

The control unit colisists of CPU )IC2091 and its peripheral circuits. It controls the TX and RX units and transfers data to and from the LCD assembly. The CPU has the f o o w ~ n gmain functions:

1 ) Switchlrig betweeri transmission and reception according to the P T slgnal input.

2)Head~ngsystem, group, frequency, and program data frorn the mernory circuit.

3)Sending frequency data to the PLL.

4)Turning the squelch on and off according to the pulse signal input from the squelch circuit.

5)Controlling the audio mute circ~iitaccording to input decode data.

6)Sending encode data

7)Sendlng data to the D/A converter.

6-1. Memory circuit

IC201 is a 2-Kbit EEPROM that stores adjustment and backup data. IC207 is a 256-Kbit flash memory that contains the transceiver control program, and

channel and Operating feature d a t a The

and

data can be easily wrltten into the memory froln external equipment. IC208 and IC210 control the writing of data into IC207.

Shift register

IC10 is an interface IC for I/O port expansion. It IS used to expand the CPU (IC209) output ports.

D/A converter

IC6 is used as a conventonal semi-fixed-resistor converter It sets the following:

1)Reference oscillator frequency

2)Transmission power

3)Modulation level

4)Audio power

6-2. TX encode data

The CPU (IC209) transmits encode data.

QT, DQT, LTR

These data items are output from CPU pin 33. The signal from this pin passes through the CR low-pass filter and goes to the summing amplifier (IC212) in the microphone amplifier. It is mixed with the audio signal and output to the splatter filter. It then goes to the D/A converter (IC6) and on to the VCXO and VCO.

6-3.RXdecode data

Low-speed data (QT, DQT, LTRI

The receive detection signal is amplified by IC2 (21 21, and passes through a ow-pass filter lC204 (112) to remove audio components. This signal is input to pin

27 of the CpU,

The CPU digitizes this signal, performs processing such as DC restoration, and decodes the signal.

IC207

IC6

1c2 (212)

Fig. 7 Control unit block diagram

TK-940 specifications

The Kenwood TK-940 is a highly regarded mobile two-way radio that has earned a reputation for its ruggedness, reliability, and excellent communication capabilities. Designed for professionals in various sectors such as public safety, transportation, and construction, the TK-940 incorporates advanced technologies to meet the demanding needs of users in the field.

One of the standout features of the TK-940 is its robust design, which complies with military specifications for durability. Its construction allows it to withstand harsh environmental conditions, making it suitable for outdoor and challenging work environments. The radio is also equipped with a water-resistant casing, ensuring that it can function reliably even in wet conditions.

The TK-940 operates in the VHF frequency range, providing wide coverage and strong signal penetration. With a power output of up to 110 watts, users can achieve long-range communication, essential for coordinating activities over large areas. The radio supports both analog and digital modes, allowing seamless integration into various communication systems while maintaining high audio clarity.

Another significant feature of the TK-940 is its enhanced audio quality. The radio is equipped with Kenwood's advanced noise cancellation technology, which minimizes background noise and ensures clear voice communication even in noisy environments. The audio output is powerful and adjustable, catering to individual user preferences.

Moreover, the TK-940 supports a variety of signaling options, includingDTMF, MDC-1200, and 2-Tone/5-Tone signaling, facilitating efficient communication. These signaling features enhance interoperability with other communication devices and systems, allowing users to communicate seamlessly with teams or dispatch centers.

Kenwood has also incorporated user-friendly functionalities into the TK-940. It boasts an intuitive user interface with programmable buttons, enabling quick access to essential features. The large, backlit display provides clear visibility and is easy to read in various lighting conditions.

The TK-940 is designed with safety in mind, featuring emergency alerts and lone worker protection, ensuring users can communicate their status in critical situations. Overall, the Kenwood TK-940 is a powerful and versatile mobile radio that combines durability, advanced technology, and user-friendly features, making it an ideal choice for professionals who require reliable communication in the field.

Kenwood TK-940 service manual Control unit

Models: TK-940