VM2050 Agile Video Modulator for "T" Channels
The R.L. Drake VM2050 is a high quality, vestigial sideband agile modulator with synthesized visual and audio carriers for "T" channel applications. "T" channel modulators utilize the return path segment (below 54 MHz) of a CATV system to feed remotely sourced programming to the cable headend for recording, processing, or redistribution. The agility of the VM2050 allows the remote site to select the channel utilized for maximum flexibility.
- Frequency agility with channels T7 through T14, coverage from 5 MHz to 54 MHz,
- High output power adjustable to +60 dBmV.
- IF loop-thru connections for scrambling encoders or IF stereo processors.
- Front panel modulation indicators and level controls to simplify installation and operation.
- Video low-pass and SAW filtering offers quality performance in congested systems.
The R.L. Drake VM2050 Video Modulator is a high quality, vestigial sideband agile modulator with synthesized visual and audio carriers. The VM2050 is designed to accept video and audio baseband signals from any NTSC video source such as a satellite receiver or similar equipment.
Front panel video and audio level controls with accompanying modulation indicators permit setting the proper modulation levels. The A/V ratio and RF output level controls are also provided on the front panel. Composite video/audio IF input and output is also provided.
Synthesized operation provides complete frequency agility, allowing front panel selection of any of 8 channels. The modulator accepts standard (sync negative) polarity video at a 0.7 - 1.5 Vp-p level. A high quality IF SAW filter eliminates adjacent channel interference. IF loop-thru capability in the VM2050 supplies an IF output prior to channel conversion. This feature provides the capability to replace the standard internally generated IF output with an alternate source of composite IF, or allows insertion of IF scrambling equipment. All of the mentioned features, combined with a carefully designed low intermodulation output stage, provide reliable operation in a densely crowded cable environment.
Download the owners manual (PDF)
| VM2050 Technical Specifications | |
|---|---|
| RF | |
| Frequency Range: | 8 channels, T7 through T14 (5.75 - 53.75 MHz) |
| Output Level: | +60 dBmV, (adjustable +50 to +60 dBmV). |
| Output Impedance: | 75 Ohms |
| Frequency stability: | ±10 ppm |
| Intercarrier Frequency: | 4.5 MHz ±10 ppm |
| A/V Radio: | Audio carrier -20 to -10 dB referenced to video carrier, adjustable. |
| Spurious Outputs: | -60 dBc typical, -58 dBc minimum, measured at -15 dB A/V ratio and with modulator output level of + 60dBmV |
| Broadband Noise: | -75 dBc typical, referenced to video carrier. (4 MHz BW @±12 MHz offset) |
| In-Channel C/N: | 65 dB typical. |
| Video | |
| Input Level for 87.5%: | 1 Vp-p ±3 dB manual gain adjustment and front panel modulation indicators. |
| Input Impedance: | 75 Ohms, return loss of 26 dB minimum |
| Frequency Response: | 20 Hz to 4.2 MHz,± 1.0 dB |
| Video S/N: | 60 dB minimum, luminance weighted. |
| Differential Gain: | Less than ±3% (10 to 90% APL) |
| Differential Phase: | Less than ±3º (10 to 90% APL) |
| L/C Delay: | Within 50 nanoseconds of 0 nanoseconds. (complies with FCC rules, 76.605) |
| Audio | |
| Input level for 25 kHz | -10 to +10 dBu manual gain |
| Deviation: | Adjustment and front panel modulation indicators. |
| Input Impedance: | 10K Ohms, unbalanced. |
| Pre-emphasis: | 75 microseconds. |
| Frequency Response: | 50Hz to 15 kHz, ±1 dB |
| Total Harmonic Distortion: | 0.5% maximum |
| Hum and Noise: | -60 dB minimum, referenced to 25 kHz peak deviation |
| Composite IF Loop | |
| Output Level (V carrier): | +28 dBmV ± 2 dB. |
| Spurious Outputs: | -60 dBc minimum. |
| Input Level (V carrier): | +28 dBmV Nominal. +30 dBmV Maximum. |
| IF Input Impedance: | 75 Ohms, return loss greater than 20 dB. |
| IF Output Impedance: | 75 Ohms, return loss greater than 15 dB |
| Isolation: | Greater than 60 dB |
| General | |
| AC Power Input: | 115 VAC, ± 10%, 60 Hz, 25 Watts. |
| Operating Temperature Range: | 0° to +50° C, ambient. |
| Size: | 19" (481mm) W x 1.75" (44mm) H x 8.75" (222mm) D. |
| Weight: | 6.8 lbs. (3.1 Kg). |
| Connectors: | Video input, IF loop and RF output are all type F. Audio input is RCA phono. |
Specifications, price, and availability are subject to change without notice or obligation.
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