Kenwood TR-7730 2m FM Transceiver

Introduction

Thank you for purchasing the Kenwood TR-7730 transceiver. This manual provides detailed instructions for installation, operation, and maintenance to ensure satisfactory and dependable performance for many years. Please read this manual carefully before use.

After Unpacking

Shipping Container: Save the original boxes and packing materials for potential future transportation, maintenance, or service needs.

Definitions:

• Note: Information that, if disregarded, may cause inconvenience but no risk of equipment damage or personal injury.
• Caution: Information that, if disregarded, may cause equipment damage but not personal injury.

Contents

Refer to the table of contents for detailed section breakdowns.

Accessories

Your TR-7730 package includes the following accessories:

• 1 Dynamic microphone (with U/D switch)
• 1 Mounting bracket
• 4 Mounting boss
• 6 Machine screws (3x6mm)
• 4 Machine screws (3x12mm)
• 4 Pan head screws (6x8mm)
• 4 Flat washers
• 4 Spring washers
• 4 Flange nuts
• 1 Front bail
• 2 Bail mounting hardware
• 2 Rear feet
• 1 DC power cord
• 1 Fuse (6A)
• 1 Miniature plug (for external speaker)

Features

• Compact and lightweight design.
• Rotary encoder, 5 kHz or 10 kHz-step digital VFO for mobile operation.
• High sensitivity RF amplifier with a low noise dual gate MOS FET.
• PLL circuit for direct VCO output at 144 MHz for excellent spurious characteristics.
• BUSY and MEMORY scan functions stop scan operation when a signal is present.
• Five memory channels with storage for two different frequencies (transmit and receive) in CH5 for "odd-split" repeater operation.
• Hand microphone with UP-DOWN switch.
• TX OFFSET Switch shifts frequencies ± 600 kHz for standard repeater operation.
• RF POWER HI (25 W) - LOW (5 W) select switch.
• Red LED frequency display.
• S and RF METER LED bar indicator.
• External BACK UP terminal.
• Extended frequency coverage (143.900-148.995 MHz) in switchable 5 kHz or 10 kHz steps for simplex and repeater operation on MARS frequencies.

Before Use

• Factory Adjustments: Do not adjust coils, trimmers, or pots as these are factory set.
• Installation Location: Do not install near heater outlets.
• Power Requirements: This unit is designed for 12 V, negative ground ONLY.
• Temperature: After parking in the sun, allow the unit to cool before transmitting.
• Polarity: Ensure correct polarity before connecting power.
• Environment: Keep equipment away from heat and out of direct sunlight.

Specifications

General

• Semiconductors: 15 ICs, 46 Transistors, 7 FETs, 91 Diodes.
• Frequency range: 144.000 to 147.995 MHz.
• Frequency synthesizer: Digital control, phase locked VCO.
• Mode: FM (F3).
• Antenna impedance: 50 ohms.
• Power requirement: 13.8 V DC ± 15%.
• Grounding: Negative.
• Operating temperature: -20°C to +60°C.
• Current drain: 0.4A (receive), 5.5A (HI transmit), 3A (LOW transmit). Less than 2.5 mA for memory back up.
• Dimensions: 147.5 mm (W) x 51.5 mm (H) x 198.0 mm (D).
• Weight: 1.5 kg (3.3 lbs).

Transmitter Section

• RF output power: HI 25 Watts min., LOW 5 Watts approx. (Adjustable).
• Modulation: Variable reactance direct shift.
• Frequency tolerance: Less than ± 20 x 10⁻⁶.
• Spurious radiation: HI Less than -60 dB, LOW Less than -53 dB.
• Maximum frequency deviation (FM): ± 5 kHz.
• Microphone: Dynamic microphone with PTT, up, down switches, 500 Ω.

Receiver Section

• Circuitry: Double conversion superheterodyne.
• Intermediate frequency: 1st IF 10.7 MHz, 2nd IF 455 kHz.
• Receiver sensitivity: Better than 0.5 µV for 30 dB S/N, Better than 0.25 µV for 12 dB SINAD.
• Receiver selectivity: More than 12 kHz (-6dB), Less than 25 kHz (-60 dB).
• Spurious response: Better than 60 dB.
• Squelch sensitivity: 0.16 µV (threshold).
• Audio output: More than 2.0 watts across 8 ohm load (10% dist.).

Note: Circuit and ratings are subject to change without notice.

Section 1. Preparation for Use

1.1 Installation

1.1.1. Interconnection

Connect the antenna and power supply as shown in Fig. 1-1 for fixed station or mobile operation.

1.1.2. Mobile Installation

Installation location: Use the supplied mounting bracket to install the transceiver under the dashboard or on the console side. Ensure adequate air circulation around the heat sink. If your car has electronic fuel injection, keep the transceiver away from the control equipment.

Antenna installation: Various 2-meter mobile antennas are available. For gutter-mount installations, ensure the antenna bracket is grounded to the car body. Refer to antenna instructions for secure mounting.

Power supply: Connect the supplied power cord with fuse directly to the battery terminals. Avoid connecting to the cigarette lighter socket due to potential poor connections and voltage drops. The microprocessor maintains operation when the power switch is OFF, drawing minimal current (approx. 2mA) for memory backup. For long periods of parking (over 1 month), disconnect the power plug to disable the backup function. A brief voltage drop during engine starting (over 2 seconds) may reset the microprocessor and clear memory.

Ignition noise: The transceiver is designed to suppress ignition noise. If excessive noise persists, consider using suppressor spark plugs.

Note: When first connecting the power cable with the power switch off, the microprocessor may be in standby. Backup current might be higher, and the display may flicker. Turn on the power to reset the microprocessor.

1.1.3. Fixed Station Installation

Power supply: The optional KPS-7 power supply is recommended for fixed station operation.

A. Installation position: Mount the transceiver securely under the dashboard or on the console, ensuring it is not obstructing the driver's knees.

B. INSTALLATION of mounting bracket: Secure the mounting bracket using screws and nuts after drilling holes in the dashboard. Adjust the installation angle as needed.

C. Antenna Installation: Various fixed station antennas are available, including ground plane and Yagi types. Ensure the antenna SWR is less than 1.5 for optimal performance. A high SWR can activate the TR-7730's protective circuit and reduce output power. The TR-7730 is factory adjusted for 25W output at approximately 146 MHz.

D. Coaxial cable connections: Route coaxial cables carefully through windows or door openings, using drip loops if possible to prevent water entry.

Antenna (Fig. 1-3): Select a fixed station antenna based on your installation space and application (DX, local QSO). Ensure SWR is less than 1.5. The RF meter indicates output power relative to SWR. The TR-7730 is factory set to deliver 25W at 146 MHz, indicated by '6' on the 10-division scale when SWR is below 1.5.

Back-up Power for Micro-Processor (memory hold):

1. With power supplied from the KPS-7, the microprocessor remains active even when the power switch is OFF, consuming minimal current (approx. 2mA).
2. For memory retention when the KPS-7 is off, connect the optional TK-1 (W09-0008-05) to the external back-up terminal.
3. In VFO operation, the kHz digit may not retain its exact value after power cycling (e.g., 146.255 MHz may become 146.250 MHz), but this does not indicate a malfunction.

Transceiver performance depends on antenna type. Ground plane antennas are suitable for local operation, while Yagi antennas offer higher gain and directivity for long-distance communication. Using both types allows for selectable operation.

Power supply: Standard voltage is 13.8V DC, with a current capacity of more than 6A. A voltage range of 12V to 16V DC is preferable. Ensure the supply has built-in protection against overcurrent and overvoltage. Battery chargers are not suitable.

Section 2. Controls and Terminals

Front Panel Controls:

1. MEMORY selector: Selects memory channels 1-5. CH5 stores separate transmit and receive frequencies for "odd-split" repeaters.
2. M switch: Inputs desired frequencies into memory channels. Press to store the displayed frequency.
3. MR switch: Recalls stored memory frequencies.
4. Frequency display: 4-digit LED display showing operating frequency (MHz • kHz).
5. BUSY indicator: Lights when the squelch is open in receive mode.
6. ON AIR indicator: LED lights during transmit mode.
7. RPT indicator: Lights when the TX OFFSET switch is set to '+' or '-' position.
8. S/RF-meter: Indicates receive signal strength (S) or transmit output (RF).
9. TX OFFSET switch: Shifts transmit frequency for repeater operation. '-' shifts down 600 kHz, '+' shifts up 600 kHz from the receive frequency. 'S' is for simplex (transmit and receive frequencies are the same).
10. M.S (MEMORY SCAN) switch: Scans memory channels 1-5. Stops on a channel with a signal. Use in conjunction with the SQUELCH control.
11. MIC connector: 6-pin connector for the supplied microphone.
12. TONE switch: Controls a user-supplied tone generator.
13. HOLD switch: Releases scan operation or stops memory scan. The microphone PTT switch also stops memory scan.
14. HI/LOW switch: Sets transmit output power to 25 W (HI) or 5 W (LOW).
15. SCAN switch: Initiates scan operation. Stops on a signal. Press again to resume scanning if the signal drops.
16. STEP switch: Selects 5 kHz or 10 kHz steps for frequency scan or microphone UP/DOWN operation.
17. Main Tuning: Rotary digital VFO control for selecting transmit and receive frequencies in 5 kHz or 10 kHz steps.
18. Squelch: Eliminates noise during no-signal periods. Adjust clockwise until noise disappears and the BUSY indicator turns off. Also used for auto scan control.
19. POWER/VOL: Combined power ON-OFF switch and volume control. Turning counterclockwise turns power OFF. Clockwise increases volume. Approximately 2mA current is drawn for microprocessor backup when power is OFF and connected to a power source. Disconnect the power cable to completely disable the transceiver.

Rear Panel Terminals & Microphone Connectors:

• 20. ANT terminal: Connect a 50Ω antenna for 2m.
• 21. EXT. SP terminal: Connect an 8Ω external speaker using the supplied plug.
• 22. DC power cord: Connect the supplied cord. Input voltage is 13.8V DC. Observe correct polarity (+: Red, -: Black).
• 23. Back up power terminal: For fixed station operation backup. Retains VFO frequency memory when the power switch is OFF. Use optional TK-1 (W09-0008-05).
• 24. PTT switch: Press-to-talk switch for transmission. Also releases scan operation.
• 25. DWN switch: Steps down the digital VFO frequency.
• 26. UP switch: Steps up the digital VFO frequency. Holding the switch continuously shifts frequency rapidly.

Section 3. Operation

3.1 Transmitter Precautions

1. Ensure a 50Ω antenna is connected.
2. Verify the transmit frequency to avoid interfering with other stations.
3. Pressing the PTT switch activates transmit mode. The ON AIR indicator lights, and the meter shows transmit power. Hold the microphone about 5 cm away when speaking.

3.2 Frequency Selection

The TR-7730 uses a PLL synthesizer. Frequencies are shifted in 5 kHz or 10 kHz steps using the main tuning dial or the microphone UP/DOWN switches. The main dial provides continuous tuning across the band. The UP/DOWN switches allow step-tuning.

Priority of Controls

All functions are microprocessor-controlled. Operate in the priority order specified in the table. For example, the digital VFO does not operate during MR operation, and scan must be released (using HOLD or PTT) for other controls to function.

Fig. 3-1 Control Priority Table

The microprocessor operates in receive mode, except when transmitting. The main dial and UP/DOWN controls are inactive during transmission. The digital VFO is factory calibrated for stability and linearity; do not remove the PLL cover.

3.4 Memory Switch

Store frequently used frequencies (repeaters, etc.) in memory channels 1-5 using the M switch. Recall frequencies using the MR switch. Channel 5 can store separate transmit and receive frequencies for "odd-split" repeaters.

Writing in memory:

1. Set the VFO to the desired frequency.
2. Select the memory channel (CH 1-4).
3. Press the M switch.

Memory recall:

1. Set the memory switch to the desired channel.
2. Press the MR switch.

Fig. 3-2 Storing Transmit Frequency in CH 5 Memory

To store the transmit frequency in CH 5 memory: Store the receive frequency first, then set the VFO to the transmit frequency, press the MIC PTT switch, and then press the M switch while holding the PTT switch.

Notes:

• An empty memory channel defaults to 144.000 MHz.
• To clear a memory, store a new frequency in its place. Memory is also cleared if the power switch is turned OFF and the unit is not connected for backup operation.

3.5 Scan Operation

The TR-7730 supports normal scan (stops on signal, resumes when signal absent) and memory scan (scans memory channels 1-5).

Normal scan:

1. Set the squelch control to the threshold point where noise disappears and the BUSY indicator is off.
2. Press the SCAN button to start. Scan stops when a signal is received and resumes when the signal drops. Press SCAN again to resume if the signal drops.
3. Press HOLD or the microphone PTT switch momentarily to hold the frequency. Scan resumes when HOLD or PTT is released, or the transceiver returns to manual operation.
4. Scan speed is approximately 120 ms per channel. Holding the SCAN button continuously doubles the speed.

Notes on Scan:

• During scan, the main dial and UP/DOWN switches are inactive. Release scan using HOLD or PTT to change frequency.
• Pressing the MR switch during scan outputs the memory frequency. Scanning does not resume after MR is released; manual operation resumes.
• In 5 kHz step scanning, the scan might stop on the channel before the signal. Press SCAN to tune to the incoming signal.

Memory scan:

1. Set the squelch control to the threshold point.
2. Press the MS switch ON to start scanning memory channels 1-5.
3. To release memory scan, set the MS switch to OFF. Press HOLD to hold the frequency. To use a frequency other than the scanned one, release memory scan by setting MS to OFF.

3.6 TX OFFSET Switch

This switch selects simplex or repeater operation:

• '+': Transmitter frequency is 600 kHz higher than the receiver frequency.
• 'S': Simplex mode; transmit and receive frequencies are the same.
• '-': Transmitter frequency is 600 kHz lower than the receiver frequency.

NOTE: OFFSET is available for both MEMORY CH and VFO operation.

3.7 Squelch

Adjust the squelch control clockwise until noise disappears and the BUSY lamp turns off. The BUSY lamp will light and the speaker will operate when a signal is received. The squelch control also affects auto scan operation. Adjust for optimal performance, especially with weak or fading signals.

3.8 HI/LOW SWITCH

For local communication, use the HI/LOW switch to reduce transmit power from 25 W to approximately 5 W. This minimizes interference and conserves power. The RF meter will indicate about 2 or 3.

3.9 AUTOPATCH OPERATION

For autopatch operation, the optional autopatch microphone MC-46 with UP/DOWN switches is recommended.

Section 3. Operation (Continued)

3.10 TONE SWITCH

This switch controls a user-supplied tone encoder. TRIO-KENWOOD does not manufacture or supply this item. Refer to Fig. 3-3 for installation details.

3.11 BAIL AND FOOT INSTALLATION

Install the front bail and rear feet using the provided hardware and machine screws as shown in Fig. 3-4.

3.12 ADJUSTMENTS

Refer to Fig. 3-5 for adjustment points on the FINAL UNIT and RX. TX UNIT.

Section 4. Additional Information

4.1 General Information

The TR-7730 is factory aligned and tested. For repairs, contact the authorized dealer. Adjustable trimmers and coils should only be readjusted by qualified technicians. Unauthorized service may void the warranty.

4.2 Battery Precaution

When charging a vehicle battery or jump-starting, disconnect the transceiver's power lead.

4.3 Ordering Spare Parts

When ordering parts, specify the transceiver's model and serial number, schematic number, printed circuit board number, part number, and quantity.

NOTE: A full service manual is available separately.

Section 5. Optional Accessories

The following accessories enhance the TR-7730's capabilities:

• 5-1 Fixed Station DC Power Supply KPS-7: Matches the TR-7730, with protection against short circuits and overloads.
• 5-2 Autopatch Microphone MC-46: Recommended for autopatch operation, featuring UP/DOWN switches.
• 5-3 External Speaker SP-40: Designed for mobile operation, matching the TR-7730's styling and tone.
• 5-4 External Speaker SP-120: Designed for fixed station operation, matching the TR-7730's styling and tone.
• 5-5 Charger TK-1: Serves as a backup power supply during main power outages.

Block Diagram

The block diagram illustrates the internal circuitry of the TR-7730, including the PLL UNIT, RX TX UNIT, CONTROL UNIT, and FINAL UNIT.