QT-300 BeltMic

World’s Smallest

The QT-300® BeltMic is the world’s smallest broadcast quality audio transmitter. Roughly the size of two AA batteries, it’s easy to conceal and comfortable to wear; actors adore it. The QT-300® series are the first transmitters unobtrusive enough to be worn by professional athletes and have revolutionized the audio experience of televised sports.

Rugged and Sporty

Originally designed for professional sports, the QT-300® BeltMic can take the abuse.  The QT-300® BeltMic is housed in solid machined aluminum, all components are of the highest quality with custom mini connectors.  This commitment to quality ensures the extreme durability and reliability that Q5X transmitters are renowned for.  Waterproofing gaskets for the antenna and Lemo mic jack help to make it splash-proof.  If you plan on going underwater, Q5X manufactures the completely waterproof QT-300® AquaMic™.

Reliable Power – with a Backup

Q5X leads the industry with the latest battery technology available.  Get 9 hours* on a single charge with the QT-300® BeltMic’s internal lithium battery.  In addition to being environmentally friendly, the internal rechargeable battery can represent a significant cost savings over replacement batteries.

State of the Art

The 3,000 frequencies of the QT-300® BeltMic are selectable from 525-600 MHz. It provides high quality broadcast audio with up to 250mw of RF output power (user programmable from 10-250mW).  The ¼″ whip antenna is fastened with a SSMA bulkhead connector. The audio connector is a high quality 5-pin Lemo connector which cleverly doubles as a battery charging port. Lavaliers by Countryman, DPA or Sanken are available separately, terminated with the proper Lemo connector.


The QT-300® BeltMic is designed to work flawlessly with the Q5X series of receivers: QR-2100, QR-2100 WB  and QR-M2.

Wall power charger with micro USB to Lemo adaptor, 1/4 whip antenna, manual, and Q5X one year warranty

Technical Data

• Dimensions: 57mm x 34mm x 14mm (2.24” x 1.34” x 0.55”)
• Weight: 42g (1.5 oz) including battery
• RF output power: adjustable from 30 to 250 mW (location specific restrictions apply)
• Number of channels: 3,000
• RF frequency range: 525 to 600 MHz
• Switching bandwidth: 75MHz (25 KHz steps)
• Modulation: FM
• Nominal deviation: +/- 40 kHz
• Peak deviation: +/- 54 kHz
• Pre-emphasis: 50 us
• Compander: Q5X DCS-QT
• Signal to Noise: 110dB (A) rms
• Frequency stability: +/- 0.001%
• Spurious Emission: <- 60 dBc
• Total harmonic distortion (THD): 0.3% at nominal deviation
• Frequency response: 50 Hz to 17,000 Hz
Note: system frequency response is dependent on the microphone element
• Audio connector: 4 pin lemo
• Antenna: 1/4 wave flex
• Battery: Internal Lithium
• Operating time: (Battery) typical 8 hrs @ 100mW
• Operating Temperatures: -10c to +45C
• Approvals: FCC, CE, Industry Canada