Drake VMM860AG Agile Modulator
Drake VMM860AG Agile Modulator
The Drake VMR860AG and VMR860AS rack mounted audio-video modulators are a synthesized, full range agile modulators covering 7 to 860 MHz.
This modulator series is popular in schools, institutions, and with CATV companies because the frequency agile VMR860AG and VMR860AS allow front panel pushwheel switch selection of standard CATV channels 2 through 135, CATV subband channels, T7 through T14, or VHF/UHF TV channels 2 through 69. This means the local operator can utilize "T" channels to return local origination programming to the control headend or generate signals on the desired operational channel.
- These Audio-Video modulators are high quality, vestigial sideband units with synthesized visual and aural carriers. The aeronautical channels are offset positive with a tolerance of ±5 kHz as required by FCC rules.
- The heterodyne conversion system, in conjunction with the use of a SAW filter, ensures optimum vestigial selectivity for adjacent channel headends.
- These modulators are designed to accept any standard audio/video source such as NTSC video and audio baseband signals from a satellite receiver, TV camera, videotape recorder, TV demodulator, or similar signal source.
- The VMR860AG or VMR860AS modulator is designed to accept standard (negative sync) polarity video at 0.6 to 1.5 Vp-p level. All level controls are located on the front panel for ease of operation. Audio and video overmodulation indicators are provided. Output level is +45 dBmV and is adjustable over a 10 dB range.
- Field-defeatable audio pre-emphasis in the VMR860AG allows transmission of BTSC encoded baseband stereo audio signals using a Drake stereo encoder.
- The VMR860AS accepts stereo audio inputs and generates a BTSC stereo audio signal without an external encoder.
- This product is also available in a desktop configuration as the VMD860AG or VMD860AS.
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VMR860AG and VMR860AS Agile Video Modulator Specifications |
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RF |
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Frequency Range: |
7 to 860 MHz; |
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FCC Frequency Offsets: |
Automatic (+12.5 kHz, +25 kHz, or none as required for each channel). |
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Output level: |
+45 dBmV (typical with 12 dB adjustment range). |
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Output Impedance: |
75 Ohms, 12 dB return loss. |
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A/V Ratio: |
Audio carrier level, adjustable from -20 to -12 dB referenced to video carrier level. |
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Frequency Stability: |
±5 ppm. |
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Intercarrier Frequency: |
4.5 MHz ±5 ppm. |
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Spurious Outputs (5 MHz to 900 MHz): |
-60 dBc typical, measured at -15 dB A/V ratio and with modulator output level of +45 dBmV. |
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In-channel C/N: |
65 dB typical, 4 MHz bandwidth. |
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Broadband Noise: |
-75 dBc typical, 4 MHz bandwidth @ +45 dBmV output. |
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Video |
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Input Level for 87.5% Modulation: |
0.6 Vp-p to 1.5 Vp-p. Manual gain adjust with |
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Input Impedance: |
75 Ohms, return loss of 20 dB minimum. |
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Frequency Response: |
20 Hz to 4.2 MHz, ±1 dB. |
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C/L Delay: |
Within 50 nSec. of FCC Predistortion curve. |
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Differential Gain: |
3% maximum (10 to 90% APL). |
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Differential Phase: |
3º maximum (10 to 90% APL). |
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Audio |
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Input Level for 25 kHz Peak Deviation: |
100 mVrms to 2.5 Vrms. Manual gain adjust with |
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Input Impedance: |
10 K Ohms, unbalanced. |
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Pre-emphasis: |
75 µSec., defeatable by internal jumper for BTSC baseband stereo encoder compatibility on VMR860AG |
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VMR860AG Frequency Response: |
40 Hz to 15 kHz, ±1.0 dB referenced to 75 µSec. pre-emphasis curve. |
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VMR860AS Frequency Response: |
50 Hz to 14 kHz, ±1.0 dB referenced to 75 µSec. pre-emphasis curve. |
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VMR860AS Stereo Separation: |
>30 dB, 100 Hz to 10 kHz |
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S/N ratio: |
65 dB. |
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Total Harmonic Distortion: |
0.5% maximum. |
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General |
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DC Power Input: |
+10 to +18 VDC / 475 mA - from supplied AC adapter. |
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Supplied AC Adapter: |
Input, 120 VAC / 60 Hz, wall adapter. |
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Operating Temperature: |
0º C to +50º C ambient. |
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Size: |
19" (48.26 cm) W x 1.75" (4.45 cm) H x 7" (17.78 cm) D. |
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Weight: |
2 lbs. 6 oz. (1.08 Kg). |
Specifications, price, and availability are subject to change without notice or obligation.
| Manufacturer | Drake |
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