Cobalt C-300

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Perfect for applications like smaller Transmitter sites Community radio, or as an Exciter where High quality audio is needed. The COBALT C-300 Transmitter has a superior audio quality and sound clarity thanks to it‘s Direct to Channel Digital technology. Running on a fully customised LINUX OS system, this low distortion modulator is available on all models within the COBALT family of FM Transmitters. Inputs and outputs include Analog, AES/EBU, Digital MPX (AES192), Ethernet, USB, GPIO, GPS Sync with built in SFN capabilities.

Stand out to your listeners with a radio market beating sound thanks to it’s built-in 4 band Audio processor with Bass enhancement, Pilot protection, Wide AGC and a whole bunch of expertly designed modern presets, so you sound great right from the start.

The modern design lets you easily read the Ultra-clear RGB display, and the intuitive Joystick controls with Haptic feedback and additional silicon buttons allows fast setup, getting you on the air even faster.

The advanced communication package with Intuitive web interface and remote control via Ethernet (https) lets you make changes or monitor the COBALT Transmitter. Full SNMP Version 3 management and the ability to send emails, alerts and monitor audio remotely gives you added confidence knowing you have full control from anywhere in the world on any device with a Web browser.

Easy access to all components and software controlled variable fan speed, will guarantee you low cost of maintenance .

The highest AC efficiency, a compact design and reduced weight mean low cost of transportation and far the lowest total cost of ownership in it‘s class.


  • Dynamic, UECP Compliant RDS Encoder
  • Direct to Digital Synthesized modulation
  • Digital MPX with MPX power Limiter
  • GPS Sync
  • 4 Band Audio Processor
  • Linux OS
  • RGB Screen
  • Ethernet Control
  • SNMP
  • Optional DC Auxillary Power Input

Technical Specifications:


Output Power (W) 300
Range (W) 10-300
RF Output connector 7/16 DIN (Female)
Input ACV @ 50/60Hz 100-240 (277 North America only)
Power Connector IEC 13A filtered
Temperature controlled fan 1
Power supplies 1
Dimensions WxDxH (cm) 48.3 x 38 x 8.8 (2RU)
Weight 7.2kg


Transmitter type Solid-state FM Stereo transmitter
Modulator Direct-to-channel (DDS)
RF Output Frequency Range VHF Band II, 87-108MHz
RF Frequency Steps 100kHz
Frequency Stability ±1 ppm or ±150Hz in 0-50⁰C range with internal 10MHz clock reference
FM Modulation Range Capability 75kHz default, 100% modulation user adjustable up to 105kHz 140%), maximum 300kHz


Power Stability ≤ ± 0.25dB
Asynchronous/AM noise ≤ -60dB
Synchronous AM s/n ratio ≤ -60dB
RF Harmonic and Spurious Suppression Meets ETSI requirements
VSWR operation Fully protected against gradual or sudden VSWR conditions.
Proportional power reduction from VSWR 1.5:1

Stereo Encoder

Performance 400Hz/1kHz test tones at modulation level ≤75kHz
Modes Stereo, Mono L+R, Mono L, Mono R
Frequency response 20Hz – 15kHz ±0.02dB
Pre-emphasis 0, 50 or 75µs
Pilot tone 19kHz, adjustable level 0-12%
Subcarriers suppression ≤ -70dB
Stereo separation ≥75dB AES/EBU input, ≥70dB Analogue input
Stereo SNR ≥80dB with 75us de-emphasis, ≥75dB without de-emphasis, both inputs
Stereo THD+N <0.03%
Crosstalk ≥70dB, between L+R and L-R due to channel matching, both inputs

Audio Inputs

Analogue 2 x XLR female, 10kΩ impedance, level adjustable 0-24dBu
Digital 24dBu AES/EBU via RJ45 per StudioHUB+, level adjustable -20-0dBFS, sampling rates 32-192 kHz

RDS Generator

Type Fully Dynamic RDS/RDS2/RBDS Generator
Protocols ASCII commands, UECP protocol and X-Command Multi-port architecture
Ports UART over USB-B & Ethernet

Communication & Control

10MHz input BNC, 50Ω terminated
1PPS input BNC, 50Ω terminated
RF sample output SMA, 50Ω, -30dBc
UART over USB USB-B, system control
USB 2 x USB-A, storage & FW upgrade
Ethernet 1 x RJ45
RS232 DB25 shared connector, system control
GPIO DB25 shared connector, 8 x output & 8 x input, all optically isolated.
Interlock/RF Mute DB25 shared connector
Analogue voltage output DB25 shared connector, 4-channel 0-5V range


Altitude 15,000 ft / 4,420m AMSL
Temperature range 0 to +45ºC working. -10 to +50ºC storage
Humidity 95% @ 35ºC, non-condensing