Kenwood TR 7850 Manual PDF

The Kenwood TR-7850 is a professional-grade VHF/UHF mobile transceiver designed for amateur radio use. This versatile radio features dual-band operation, cross-band repeat function, wide frequency coverage, multiple operating modes, and robust construction for reliable performance in various conditions. Below are key sections covering specifications, operation, programming, installation, and troubleshooting.

Features Overview

Key features: Dual-band transceiver, cross-band repeating, 50W output power, 200 memory channels, CTCSS/DCS encode/decode, weather alert function, and programmable scanning.

Feature	Description
Frequency Range	VHF: 136-174 MHz, UHF: 400-480 MHz
Output Power	High: 50W/45W, Mid: 25W/20W, Low: 5W/5W
Memory Channels	200 channels (100 per band)
Operating Modes	FM, FM-N, AM (receive only)
Cross-band Repeat	Full duplex cross-band repeating function
CTCSS/DCS	50 CTCSS tones, 104 DCS codes
Scanning	Programmable memory and band scanning
Weather Alert	NOAA weather channels with alert function
Power Supply	13.8V DC ±15% negative ground
Dimensions	140(W) × 40(H) × 180(D) mm

Technical Specifications

• Frequency Coverage: VHF 136-174 MHz, UHF 400-480 MHz
• Power Output: VHF: 50W max, UHF: 45W max
• Modulation System: 16KΦF3E (FM), 11KΦF3E (FM-N)
• Antenna Impedance: 50 ohms
• Current Consumption: Receive: 0.5A (squelched), Transmit: 13A max
• Operating Temperature: -20°C to +60°C
• Weight: Approximately 1.2 kg
• Speaker Output: 2W at 8 ohms
• Microphone Connector: 8-pin modular jack

Front Panel Controls

Main controls: Power/VOL knob, SQL knob, Channel selector, Function key, Band key, VFO/MR key, Call key, A/B band selector, and LCD display.

LCD Display Indicators: A/B band, frequency, memory channel, SQL, TONE, DCS, REPT, LOW power, busy, and various status icons.

Function Key Operations: Hold F key for 1 second to access secondary functions including TONE, DCS, REPT, LAMP, LOCK, and SET menu.

Basic Operation

Power on: Rotate VOL knob clockwise. Adjust volume and squelch as needed.

1. Select band: Press A/B key to switch between VHF and UHF bands.
2. Frequency entry: Use keypad to directly enter desired frequency.
3. Memory operation: Press VFO/MR to switch between VFO and memory modes.
4. Channel selection: Rotate channel selector knob or use up/down keys.
5. Transmit: Press and hold PTT button on microphone.

NOTE: Ensure proper antenna connection before transmitting.

Programming Instructions

Memory channel programming:

1. Select frequency in VFO mode.
2. Press F then MR key to enter memory write mode.
3. Select memory channel number.
4. Press MR key again to store.
5. Set additional parameters (TONE, DCS, etc.) as needed.

CTCSS/DCS Programming: Press F + TONE to access tone menu, select encode/decode/both, choose tone/code.

Scan Programming: Set scan edges and resume conditions in SET menu.

Installation Guide

Mounting and connection procedures:

1. Choose mounting location with adequate ventilation.
2. Connect DC power cables (red to positive, black to negative).
3. Install appropriate antenna for desired frequency bands.
4. Connect microphone to 8-pin modular jack.
5. Secure all connections and test operation.

WARNING! Use proper fuse (15A recommended) in power line. Ensure secure ground connection.

Cross-band Repeat Function

Enable cross-band repeating to relay signals between VHF and UHF bands.

1. Press F + REPT to enter cross-band repeat mode.
2. Set transmit and receive frequencies on opposite bands.
3. Adjust squelch levels appropriately.
4. Monitor operation and adjust time-out timer if needed.

CAUTION: Ensure compliance with local regulations when using cross-band repeat function.

DTMF Operations

DTMF functions for remote control and signaling:

• DTMF Encode: Use microphone keypad to send DTMF tones
• DTMF Memory: Store frequently used sequences in DTMF memories
• Auto Dial: Program speed dial numbers for quick calling
• DTMF Squelch: Set codes for selective calling

Access DTMF settings through SET menu (F + SET).

Maintenance & Care

Regular maintenance ensures optimal performance:

• Keep unit clean and free of dust
• Check antenna connections periodically
• Verify power connections remain secure
• Avoid exposure to moisture and extreme temperatures
• Use only approved accessories and antennas

WARNING: Disconnect power before performing any maintenance.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Power connection/fuse	Check power cables; verify fuse; ensure proper voltage.
No transmission	Settings/antenna	Check PTT function; verify antenna connection; check power settings.
Poor reception	Antenna/squelch	Verify antenna installation; adjust squelch; check connections.
Memory loss	Power interruption	Re-program memory channels; check backup battery if applicable.
Overheating	Ventilation/power	Ensure adequate ventilation; check for obstructions; verify power settings.

Reset Procedure: Turn off unit, hold F + MR + POWER to factory reset.

Warranty Information

Kenwood provides limited warranty coverage for the TR-7850 transceiver. Warranty period and terms may vary by region. Retain original purchase receipt for warranty service.

Service Centers: Authorized Kenwood service centers only. Do not attempt unauthorized repairs.

Contact: For technical support and warranty claims, contact Kenwood authorized dealer or visit www.kenwood.com