The Garmin Signal™ VHF 400 is a compact, fixed-mount VHF radio designed for recreational and professional mariners. Featuring integrated GPS and AIS transponding capabilities, it delivers reliable two-way communication with exceptional clarity in coastal and offshore waters. Built with a rugged, waterproof design, this radio withstands harsh marine environments whilst maintaining consistent performance. The intuitive interface allows quick access to essential functions, including distress calling, weather alerts, and vessel tracking. With dual-watch capability and programmable channels, you can monitor multiple frequencies simultaneously. The integrated speaker and microphone system ensures clear communication even in challenging conditions. Perfect for cruising, fishing, or commercial operations where dependable VHF connectivity is essential.

Quickly transmit a distress signal to nearby vessels with the distress button, which uses Class D DSC to automatically send crucial information that can help emergency responders. You can also use the intuitive DSC features to quickly initiate contact with other AIS-equipped vessels - simply select the vessel on the AIS plotter view, and call them with a tap of a button.

Configure the radio, program the MMSI number, and get over-the-air software updates with the Active Captain App via built-in Wi‑Fi^® connectivity.

Installation is simple since VHF/DSC/AIS features only require a single VHF antenna and the GPS antenna/receiver is built into the unit. Chartplotter integration is seamless via the NMEA 2000^® network and Garmin BlueNet™ Network.

AIS TRANSPONDER

Maintain situational awareness with the built-in Class B AIS SOTDMA transponder

FIST MIC

The included fist mic features a built-in speaker (5-watt RMS) and can be mounted in a different location to the head unit.

RUGGED DESIGN

The radio is built to withstand harsh marine environments with an IPX7 rating.

EXTERNAL SPEAKER SUPPORT

Connect a compatible external speaker for more playback options beyond the built-in speaker on the fist mic.

HAILER WITH LISTEN BACK

Connect the radio to a compatible loudhailer for broadcasting announcements. The listen back feature gathers background sounds that can be heard through the fist mic or external speaker.

ADAPTIVE NOISE CANCELLATION

Advanced noise cancellation uses machine learning algorithms to eliminate wind, wave and engine noise for our cleanest audio experience.

AUTOMATED SQUELCH

Radio activity is constantly monitored to eliminate unnecessary noise and static. You also have the option for manual fine-tuning.

ADVANCED WATCH MODES

All VHF channels are continuously scanned for activity in the background, allowing you to maintain watch over channel 16 and all your favourite preset channels simultaneously.

VHF AUDIO PLAYBACK

Didn’t catch that message? Replay it with VHF audio playback, and listen to audio messages for up to 3 minutes on any channel.

Unit size	Head Unit: 75 x 160 x 104 mm (3″ x 6.3″ x 4.1″) Fist Mic: 100 x 60 x 31 mm (3.9″ x 2.4″ x 1.2″)
Weight	Head Unit: 655 g (1.45 lbs) Fist Mic: 245 g (0.54 lbs)
Operating voltage	9.6 - 32 VDC
Water rating	IPX7
Display Type	Colour IPS LCD, capacitive touch
Display Size	3.5″ (89 mm)
Display Resolution	640 x 480 pixels
Operating temperature	–20° to 55° C (–4° to 131° F)
Inland waterways (ATIS)
Backlight	1,000 nits
Multi-language interface

VHF Features
Adaptive noise cancellation
Audio record and playback
Auto squelch
Dual/Tri watch
Presets watch
NOAA weather alert
NOAA weather watch
Loud hailer
Loud Hailer listen-back
Intercom support
AIS target display
AIS collision and MOB alarms
Integrated AIS transponder

VHF Radio
Region	All U.S., Canadian and International marine channels; NOAA weather channels
VHF frequency range Tx	156.025–162.025 MHz
VHF frequency range Rx	156.025–163.275 MHz
VHF transmit power (max)	25 W, 1 W (high, low)
Transmitter frequency tolerance	+/0.3 kHz
Adjacent channel power	More than 70 dB
Spurious emissions	Less than –80 dBc (at 25 W)
Sensitivity (12 dB SINAD)	-118 dBm (-11 dBu/0.28 uV)
Adjacent channel selectivity	80 dB
Spurious response	More than 75 dB
VHF intermodulation	More than 75 dB
Max antenna gain	6 dBi

Class D DSC
Class	Class D
Sensitivity (1% BER)	-117 dBm (-10 dBu/0.32 uV)
Adjacent channel selectivity	80 dB
Spurious response	More than 75 dB
Intermodulation	More than 75 dB

AIS Transponder Features
Remote station support	RM 100 (x5)

AIS
Class	SOTDMA Class B
Long range position reports (Msg 27)
Frequency range	156.025–162.025 MHz
AIS power output	5 W
AIS Sensitivity (20% PER)	-115 dBm (-8 dBu/0.4 uV)
Adjacent channel selectivity	80 dB
Spurious response	More than 75 dB
Intermodulation	More than 65 dB

GNSS
Integrated GNSS receiver
Integrated GNSS antenna
Constellations	GPS, GLONASS, BeiDou, Galilleo
Differential support	SBAS, AIS Msg 17
Navigation rate	10 Hz

Sensors
NMEA 2000^® compatible
Battery voltage

Audio
Max speaker output power{}	Fist Mic: 5 W RMS, < 1% THD
Max external speaker output power	15 W RMS, < 1% THD, 4 Ω
Max hailer loudspeaker output power	25 W RMS, < 1% THD, 4 Ω

Tactical features
Night vision mode
Stealth mode

Electrical features
Typical current draw at 12 Vdc	Head Unit: 700 mA, 6 A max Fist Mic: 90 mA, 0.9 A max
Compass safe distance	Head Unit: 70 cm (27.6″) Fist Mic: 15.8 cm (40″)

Networking & Connections
Garmin BlueNet™ Network	GMN 1.0/2.0
Wireless Connectivity	Access point for mobile phones, 802.11b/g/n, integrated antenna
Wireless security	WPA2 Personal
External GNSS antenna connector	SMA
Ant connector	SO-239 (50 Ω)

Security Information
Security updates until at least (YYYY-MM-DD)	2028-05-28

In The Box:

Garmin Signal™ VHF 400 head unit
Fist mic
Sun cover
Head unit power and external audio cable with fuse (2 m)
Fist mic power cable with fuse (2 m)
Drop cable for NMEA 2000^® network (2 m)
Mounting hardware
Mounting template
Documentation

AIS TRANSPONDER

RUGGED DESIGN

EXTERNAL SPEAKER SUPPORT

HAILER WITH LISTEN BACK

ADAPTIVE NOISE CANCELLATION

AUTOMATED SQUELCH

ADVANCED WATCH MODES

VHF AUDIO PLAYBACK

VHF Features

VHF Radio

Class D DSC

AIS Transponder Features

AIS

GNSS

Sensors

Audio

Tactical features

Electrical features

Networking & Connections

Security Information

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