IF44 NTSC Video IF

The IF44 is a standard 44 MHz NTSC video IF system for the purpose of obtaining baseband video and audio signals from a NTSC video modulated carrier at 44 MHz. This is the output from standard TV and cable tuners and is the standard intermediate frequency used in almost all NTSC TV receivers. This IF system is designed for hobbyist use, servicing, experimental, amateur TV, or professional use and will, with suitable downconverters or other RF front ends, provide the functions of a complete video and audio tuner for both commercial and amateur television. This IF will directly interface to any video device or RF front end having 44 MHz output, with a standard NTSC monitor or other video device. While many TV sets and VCRs provide baseband video output, this IF system provides the same function in a much smaller package with lower power requirements, and avoids the tying up of a more expensive video device that would otherwise be needed for this purpose. The IF44 NTSC IF system has a built in SAW filter preamp with gain sufficient to compensate for the 20+ dB loss inherent in SAW filters used in TV IF systems. In addition to the SAW IF filter, an LSI IF amplifier is used, and an on board 4.5 MHz sound IF system is provided. Ceramic filters greatly simplify alignment and only a signal source, monitor, and VOM are necessary for setup. Gain is over 70 dB (video out to IF input) and is compatible with typical 30 to 40 dB gain TV tuners, enabling adequate sensitivity and signal to noise ratio. This IF system is also useful in conjunction with a monitor as a servicing device for diagnostic testing of RF tuners used in TV receivers. The outputs are standard 1V p-p neg sync 75 ohm NTSC video and 0.5 V rms hi-Z (Approx 5Kohm) audio line level signals, and also reverse AGC output to directly interface with 440, 900, and 1300 MHz ATV downconverters. The IF system will directly drive most monitors, camcorders, and other video devices. If needed, AFC voltage is available and can be used for LO control of the front end if this is required. AFC is defeatable with a switch connection to ground. Other applications of this devices include use as a receiving component in Amateur TV equipment, in ATV repeaters as a receiver IF strip, and also as a video signal source for test purposes. The circuit board measures 2.5 wide X 4.0 long X 1 inch high and operates from a 12-14.4 volt DC negative ground power source. Power consumption is about 2.2 to 3.0 watts (at 12 and 14.4 V) depending on signal levels and the supply voltage.