Video Line Amplifier-Adjustable Gain & EQ

The RDL TX-VLA1 is a video line amplifier for raising video level and applying high-frequency equalization before a signal travels over a long cable. It supports NTSC or PAL video and combines adjustable gain, adjustable EQ, 75 Ω BNC connections, and 10 MHz bandwidth in a small-format device. It is designed to compensate for cable-related level loss and high-frequency attenuation that can degrade color signals and reduce monochrome image resolution.

Ideal Use Cases

The TX-VLA1 is particularly suited to security and surveillance installations in which a camera is located a significant distance from monitoring or recording equipment. Long cable runs can reduce the overall video level while attenuating higher-frequency signal components. By placing the amplifier at the camera, the gain and equalization can be adjusted before the video travels through the cable. The EQ adjustment supports video cable runs as long as 2,000 feet, or 600 meters. The unit can also serve other NTSC or PAL applications requiring adjustable video-level correction over a long 75 Ω connection.

Why Choose This Model

This model addresses two forms of cable loss through separate adjustable functions. Gain is adjustable from unity to +5 dB, allowing the overall video level to be increased as needed. Equalization ranges from flat to +4 dB at 3.58 MHz and from flat to +7 dB at 5 MHz. These controls provide a way to compensate for both the general reduction in signal level and the greater loss experienced by higher-frequency video components. A 10 MHz bandwidth accommodates the video signal, while residual noise is rated below -65 dB when referenced to a 1 V p-p signal.

Installation and Integration

The TX-VLA1 accepts a 1 V p-p video signal through a ground-referenced, 75 Ω BNC input. Its output uses a ground-referenced BNC connection with a 75 Ω source termination. For camera-based systems, the unit may be located directly at the camera so compensation is applied before cable losses accumulate. Power flexibility supports installation where different voltage sources are available: the amplifier requires a ground-referenced 12 to 33 Vdc or 12 to 24 Vac source at 30 mA. Recommended power supplies are the PS-24AS for the USA and PS-24AX for international use; the power supply is not included.

Performance Highlights

• Adjustable gain from unity to +5 dB for compensating for reduced overall video level.
• Adjustable equalization from flat to +4 dB at 3.58 MHz and flat to +7 dB at 5 MHz.
• Support for video cable lengths up to 2,000 feet (600 meters).
• 10 MHz bandwidth and support for both NTSC and PAL video.
• Residual noise below -65 dB, referenced to a 1 V p-p input.
• Ground-referenced 75 Ω BNC input and source-terminated 75 Ω BNC output.
• Operating range from 10° C to 50° C.

The equalization curve is optimized at each setting for the flattest response of video signal components without square-wave overshoot. This targeted response is intended to correct high-frequency attenuation while maintaining the shape of the video signal components.

What Makes It Different

A basic level amplifier addresses overall amplitude but does not necessarily correct the unequal loss of higher-frequency information. The TX-VLA1 combines level adjustment with frequency equalization, directly addressing both cable-loss effects described for remote-camera installations. Its adjustable controls allow compensation to be matched to the cable run rather than limiting the system to a fixed gain or EQ setting. The broad ground-referenced AC or DC power range also allows operation from several available voltage sources. These capabilities are provided in a small-size video amplifier intended to deliver high-quality video over extended lines.

Final Assessment

The RDL TX-VLA1 is a focused solution for NTSC or PAL video systems affected by long-cable attenuation. Its unity-to-+5 dB gain range, adjustable high-frequency equalization, 10 MHz bandwidth, low residual-noise specification, and standard 75 Ω BNC connections provide the controls needed to compensate at the source. For camera runs extending as far as 2,000 feet, it offers practical adjustment of both overall level and high-frequency response.