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  • Regular price $450.00
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Introducing the CTX3, our most compact transmitter to date and likely the smallest UHF Audio Surveillance Transmitter available worldwide. With dimensions of only 6.39mm x 18.56mm and a thickness of 0.8mm, the CTX3 sets a new standard in size efficiency. This transmitter is now available with a new extremely sensitive KNOWLES microphone, and a new high-powered crystal generating 20mW of RF power, ensuring superior frequency stability and delivering enhanced audio sensitivity. For custom power options to extend the operating time, please feel free to contact us for further assistance.

The CTX3 comes pre-equipped with a rechargeable LiPo mounted, providing over 12 hours of continuous audio surveillance. To activate the transmitter, a magnet is used to activate a tiny Hall-Sensor switch that turns the transmitter on or off. Alternatively, the CTX3 can be used as a standalone device with the (+) / (-) terminal pads tinned, allowing you to attach your own power or battery supply (ranging from 3V to 3.7V). This flexibility opens the door to virtually limitless operational time, enabling you to customize the power source to meet your specific needs. 

The transmitter offers +/- solderable power/battery input terminals, facilitating the attachment of custom power supply packs. This feature allows for the significant extension of the surveillance operation time using various Li-Ion power options or custom battery packs, providing enhanced versatility.

The CTX3 features a discreet design without switches or indicator lights, ensuring covert operation.

Once the battery is inserted, the CTX3 functions as a permanent, always-on "hot-microphone," immediately initiating live transmission of ambient and surrounding audio without interruption on the Ultra High-Frequency band. In a cluttered urban environment, the CTX3 broadcasts audio over a distance of 700 meters, extending up to 1.2 kilometers with Line-of-Sight (LOS) transmission. It effectively transmits audio through obstacles such as concrete, drywall, and dense vegetation.

Use the CTX3 for discreet acoustic monitoring of areas of interest. We recommend utilizing any handheld UHF receiver capable of tuning into the standard frequency range of 400MHz-434MHz, which is supported by most UHF receivers. For optimal performance, we suggest the Baofeng UV-5R or the AnyTone AT-318UV as our recommended handheld receivers. Additionally, you can also use any of our transmitters with SDRs (Software-Defined Radios). Your CTX3 will arrive with its specific Tx/Rx frequency clearly noted on its back, ensuring seamless compatibility with your receiver of choice.

Power Supply Options

2x 6.8mm button cells (3V) : 12 Hours Hours Of Continuous Operation.

1x CR2032 (3v) : 29 Hours Of Continuous Operation.

1x 2600 mAh 18650 (3v) : 260 Hours Of Continuous Operation.

1x 3600 mAh 18650 (3v) : 360 Hours Of Continuous Operation.

2x AA Alkaline (3V) : 210 Hours Of Continuous Operation.

Dimensions 6.39mm x 18.56mm x .8mm

CUI: 100 Hz ~ 20 kHz Analog Microphone Electret Condenser Omnidirectional (-42dB ±3dB @ 94dB SPL)

KNOWLES BJ-21590: 300 Hz ~ 5 kHz Analog Microphone Magnetic Omnidirectional (-75.5dB ±3dB @ 74dB SPL)

Weight 1g
Output (RF) power  20mW
Antenna Alpha Wire 8 in. Micro Coaxial Cable 38 AWG
Frequency Range

433MHz-439 MHz, 2.5 kHz step.

Effective Range 15m From Centre. 
Stability  Highly Stable. Crystal Referenced Phase-Locked Loop.
Crystal 00k/ASK Data Transmitter.

In order to maintain its longevity, the CTX3 is potted with a compound that seals all onboard components, only the microphone and the battery terminal pads are accessible and made visible.

We can design for your needs. TINYTX has designed and manufactured hidden and covertly disguised audio surveillance transmitters for several client projects and applications. Contact us for turnkey solutions.