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The STX room transmitter has been designed with an extra buffer/amplifier on board. This effectively increases the output power and improves the transmitter stability. The finished size of the module is just 22mm x 22mm including the on board electret microphone and with a height of just 1 5mm. the whole package is very small for such high performance results. Crystal clear reproduction of the slightest sounds up to 25 feet away will be transmitted to a range of 1500 metres. The STX will operate on a supply voltage of between 6-12V with 9V being the optimum. The output frequency is fully tuneable from 100-120MHz giving operation on both normal VHF FM or airband radios. Operating on 9V~ the STX gives an output power of approximately 50mW at a current drain of 1 5mA Typical Duracell MN1 604 will power the STX continuously for about 30 hours.
In the absence of any sounds or speech the VXT module lies dormant using only a very low standby current. When sounds are detected over a certain level the VXT switches on the transmitter section. Once triggered the transmitter will stay on for a preset time which prevents it from switching off during short pauses in speech. The sensitivity at which it triggers and the period it stays on are both variable with miniature on-board controls. An LED indicates when it is triggered. The VXT has incredible sensitivity, on maximum it can trigger from a door handle being operated from 25 feet away, and the on board microphone clearly reproduces any sounds at a range of 1000 metres. Fully tuneable output, from 100-120MHz covering both normal VHF FM and airband. The VXT measures just 2Omm x 67mm and operates from a 9V supply. Current drain at standby is a mere 2mA giving a standby life from a typical MN1604 Duracell battery of around 250 hours, that's 11/2 weeks! Once triggered the current drain rises to about 1 8mA giving about 25 hours continuous transmission at an output power of around 20mW.
For situations not requiring the ultimate in miniaturisation offered by the UTLX module the TLX7OO being 2Omm x 2Omm is considerably easier to assemble and has higher performance. It is the 'industry standard' telephone transmitter and this module can be found in many finished products sold elsewhere at a considerably higher prices! Power is taken from the telephone line on which it is connected so no batteries are required and the TLX7OO automatically switches on and off as the phone is used. When in use both sides of the conversation are transmitted at an output power of around 20mW which provides an effective range of 1000 metres. Output frequency is fully tuneable between 100-115MHz and can therefore be monitored either on normal VHF FM or airband.
SCDM Sub carrier audio demodulator
To monitor a transmission from a subcarrier transmitter such as the SCRX or SCLX requires the use of the SCDM demodulator. This takes the audio output from the headphone socket of the receiver which contains the ultrasonic carrier filters this carrier out and amplifies it up. This resultant signal is then processed to demodulate the audio from the carrier. Finally the recovered audio is fed to a small audio amplifier suitable for driving a pair of headphones. The carrier demodulating frequency and output volume are controlled by two board mounted potentiometers and the overall size of the board is 32mm x 70mm. The module requires a 9- 1 2V supply and has an audio output of around 250mW.
Narrow band FM crystal controlled equipment
Narrow Band FM crystal controlled transmitters, often shortened to NBFM, are the most sophisticated of all surveillance transmitters. They operate on an exact frequency and are held there accurately by the quartz crystal. The audio that they transmit is condensed down to only occupy a very small portion of the band which makes them very secure. The following range of '0' series transmitters can only be monitored with the use of the ORX180 receiver module, or a scanner receiver which covers the necessary frequency and has a narrowband capability. All of the 'Q' series transmitters operate on the 180,000MHz band although other frequencies can be supplied to special order. A frequency counter and signal strength meter, such as our FS-1, are useful although not vital, when setting up these transmitters.
QTX180 NBFM room transmitter
The QTx1 80 is a high performance NBFM crystal controlled room transmitter. ft employs a high sensitivity on-board electret condenser microphone to detect the slightest sound. The sensitivity of the audio stage can be adjusted to suit the particular application with a miniature preset control on-board. The board measures just 2Omm x 67mm and operates from a 9V supply. Current drain is 1 5mA giving a continuous transmission time from a Duracell MN1 604 battery of around 30 hours. The output power of I 0mW is sufficient for a range of 1000 metres. Operating frequency 180,000MHZ.
QSX18O LIne powered NBFM telephone transmitter
For long term telephone monitoring replacing batteries can be very troublesome and long term transmission increases the chance of detection. To avoid these problems the QSX1 80 is a line powered crystal controlled NBFM transmitter unit which requires no batteries. Power is drawn from the line when the phone is in use and the transmitter is automatically switched on and off. Both sides of any conversation on the line will be clearly transmitted. Two simple connections to the line are all that is required. The QSX1 80 measures just 32mm x 37mm and has an output power of approximately 5mW providing a range of 500 metres. Operating frequency 180,000MHz.
TKX9OO Wideband signalling/tracking transmitter
The TKX9OO is the broadband version of the QX900 signalling/tracking transmitter described elsewhere in this catalogue. It's output signal is fully tuneable from 100-120MHz making it suitable for use on normal VHF FM or airband receivers. The audio bleeping signal is fully adjustable with miniature on-board controls in bleep length and pitch making it ideal for all forms of signalling or alarm use. ft operates from a 9V supply and has powerful 100mW output providing a range of 3000 metres. Current drain is around 50mA so a continuous transmission time of about 10 hours can be expected from a Duracell MN1 604. Board size 25mm x 63mm.
XT89 Wideband crystal controlled room transmitter
If the secure frequency of the 'Q' range of transmitters is not vital but the crystal stability is then the high performance XT89 will meet the criteria. Designed to transmit on 108.00MHz it is a. wideband transmission and can therefore be received on a normal VHF FM radio with no modifications. It comes complete with a high sensitivity electret microphone capable of detecting the slightest sound. Board size is 28mm x 85mm and operating voltage is 9V. The current drain is around 50mA giving a transmitting time of about 10 hours continuous from a Duracell type battery. Output power is in the region of 50mW giving a useful range of 1500 metres.
QRX180 NBFM Receiver module
The QRX180 is a crystal controlled NBFM receiver module suitable for monitoring any of our 'Q' series transmitters It is very sensitive and operates on a single channel frequency of 180.000MHZ although other frequencies can be supplied to special order. The construction and alignment of narrow band crystal controlled equipment is difficult without specialised equipment so to avoid this problem the complete RF front end is supplied ready assembled and aligned as a separate module. This then drops into position on the main board leaving you to construct the audio and control stages A 250mW audio output for headphones is provided by the module. The board size measures 6Omm x 75mm and the unit operates from a 9V supply and has a current drain of around 2OmA.
MBX-1 Hi-Fi micro-broadcaster
Although the MBX-1 is not strictly a surveillance device it still warrants description in this catalogue By connecting the MBX-1 into the headphone output of your hi-fi, tape or CD player you can transmit high fidelity music to a nearby radio. Imagine being able to listen to your favourite music anywhere round your house or garden, in the bath or in the garage! No longer will you have to put up with a DJ's choice of music and suffer the banal chit-chat between tracks! The MBX-1 combines the stereo signal input in the on-board mixer and transmits it up to 250 metres on a frequency adjustable between 90-110MHz. Its not a true stereo transmission but this has little effect on the quality. The input sensitivity on both channels is fully adjustable for the best reproduction and the overall size of the board is just 27mm x 60mm. Power requirements are 9V and current drain is just l2mA.
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