This transmitter board is a redesigned and updated version of our ATV12-440. It has better audio and video performance and several new features. It will generate a complete NTSC video signal with a 4.5 MHz FM sound subcarrier, modulated on a UHF carrier. It operates from a nominal 12V (11-14.4V) volt power supply. The kit includes a crystal for 439.25 MHz This UHF signal can be received on any standard TV receiver fitted with a suitable RF down converter capable of tuning the 420-450 MHz Amateur band. If the TV receiver is capable of tuning these frequencies directly, no converter is needed. CH 60 on some cable ready sets is 439.25 MHz, and it is possible to modify certain sets to do this, but for best results a dedicated downconverter outputting on an unused VHF channel (CH3 or CH4) is recommended. This allows an optimized RF front end for best reception range. The small size (2.50 X 4.00) is comparable to many small PC board cameras and is small enough for R/C applications in which a video link is needed, robotics, amateur TV, and remote sensing as limited by current amateur regulations. For export purposes only, this transmitter may be operated up to 520 MHz for LPTV broadcasting over a small village or community, as a back up or temporary station, or where costs and logistics preclude a larger unit. Both NTSC and PAL can be accommodated. Lead acid, nicad, or alkaline power packs may be used. More than 15 volts is not recommended. Power output will be typically from 1.5 to 3 watts PEP over this voltage range. Low voltage operation from 9.6 volt NICAD packs is possible (reduced RF output power) with a few minor adjustments. This transmitter uses a crystal oscillator and multiplier chain to generate the final output frequency. A crystal is supplied for 439.25 MHz. There is space on board for extra crystals. Third overtone crystals in the 54 MHz range are used. The transmitter requires standard NTSC or PAL video. The transmitter audio can also be retuned for a 5.5 MHz or 6.0 MHz sound subcarrier used by the PAL system. 75 usec audio preemphasis is used although this is easily changed to 50 usec for PAL. The video input requirement is standard 1V p-p 75 ohms, negative sync. Audio inputs from .05V to 1 Volt can be used.

NOTE THAT A VALID AMATEUR LICENSE PERMITTING OPERATION AT 440 MHz IS A REQUIREMENT FOR OPERATION OF THIS DEVICE IN THE USA. In the USA this will be a Technician Class (code free) license, so if you can build this kit you should easily be able to pass the required exam.

OPERATION OF THIS DEVICE ON THE AIR ON COMMERCIAL TV FREQUENCIES IS ILLEGAL IN THE USA and for other nations, check local laws. Note that this transmitter has not been submitted for type approval and is intended for AMATEUR USE ONLY by suitably licensed amateurs and for no other purposes. It may be used in export applications for temporary or standby LPTV broadcasting subject to local laws.

The kit can be easily assembled in two to five evenings, depending on experience. There is some small work so suitable tools should be available. Some experience is assumed, but the average electronic hobbyist will have few if any problems. Some familiarity with RF circuitry is assumed. An assembled and tested PC board or complete transmitter mounted in NC531 case is available for those who would prefer a ready built and tested unit.

FEATURES Model ATV12-440 MK2. Specs at 13.8 V DC, 439.25 MHz unless noted
* Small size (2.5 X 4.0 X 1.0 inches), light weight 2 oz (56 gr).
* Can operate from batteries for portable or R/C usage.
* Output 2W P.E.P. min, 2.5 W typical at 13.8 VDC.
* Built in audio FM subcarrier generator 4.5 MHz.
* Audio easily retuned for 5.5 or 6.0 MHz PAL operation.
* Defeatable audio section with on board disconnect.
* Wideband video modulator > 4 MHz BW.
* Adjustable clamp and video levels.
* Built in tuneup LED RF indicator.
* LEDs for keying indicator, and modulation indicator.
* Directly Interfaces with our Voice Identifier
* Designed for 420-450 MHz ATV. Useable to 520 MHz.
* Crystal for 439.25 MHz included.
* Extra position for two other crystals on board (see below for others).
* On-board audio, video gain, clamp level controls.
* Adjustable on-board audio subcarrier level control.
* Accepts standard NTSC video and audio levels.
* Audio preemphasis 75 usec, easily changed to PAL 50 usec.
* Directly interfaces with most cameras, VTRs, VCRs, and most microphones.
* On-board 8 pin header connector for easy PC board camera interface.
* Built in keying circuit controls transmitter and camera for R/C applications.
* No expensive, difficult to get RF modules or ASICs used
* Rugged construction, easily tuned up with VOM and dummy load.
* Obsolescence proof.
* Uses inexpensive, standard, discrete parts for easy servicing.
SPECIFICATIONS **        All Specs at 13.8 V DC, 439.25 MHz unless noted
Frequency Range 420-520 MHz designed for 70 cm amateur band
RF Power Output 2.5W PEP typical, 2W minimum at 13.8 VDC
RF Load Impedance 50 ohms, 1.5 to 1 VSWR or better recommended.
Spurious outputs Less than -40 dBc, built in LP filter.
Modulation Video - high level AM Audio - FM 25 KHz deviation
Preemphasis 75 us preemphasis, easily changed to 50 usec
Video BW 10 Hz to > 4 MHz. Suitable for color or B/W.
Video controls Adjustable clamp level and video gain
Video Input 0.5 to 1.5 V P-P, 75 ohm, Neg sync NTSC or PAL
Audio Controls Audio gain, Audio Subcarrier Level
Audio Input .05 to 1 V RMS, Z > 5k ohm, 50-10000 Hz.
Audio subcarrier 4.5 MHz nominal, 5.5 or 6.0 MHz capability for PAL.
Subcarrier level Adjustable level, -40 to -10 dB, defeatable.
Power Supply 11-14.4 VDC 9-15 VDC useable, Negative ground
Current Drain 450-550 mA. @ 13.8 VDC typical
Mechanical 2.5W X 4.0L X 1.0H, Wt. 2 oz (56 gr).
Crystals 3rd OT series HC 49U .01%
Crystal Frequency Xmtr freq / 8, space for three crystals
Indicators On board LEDS for RF output,modulation, and keying.
** Specs guaranteed 420-450 MHz, 13.8 VDC only
Basic Kit : PC board, one crystal and all parts that mount on it to build working PC board 131.00
Completed PC Board, Assembled and tested w / DC and RF leads, no connectors or case 185.00
Complete unit assembled and tested, mounted in NC531 case w / connectors, ready for use 245.00

Prices in US Dollars do not include Shipping and handling  (See Order Form)

PO Box 200, Hartford NY 12838-0200
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