VMR806AG Agile Video Modulator

The Drake VMR806AG audio-video modulator is a synthesized, full range agile modulator covering 7 to 806 MHz.

This modulator is popular in schools, institutions, and with CATV companies because the frequency agile VMR806AG allows front panel push wheel switch selection of standard CATV channels 2 through 125, 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.

The R.L. Drake VMR806AG Audio-Video Modulator is a high quality, vestigial sideband unit 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. An optional FCC predistortion SAW response is also available for the VMR806AG.

The modulator is 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 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 allows transmission of BTSC encoded baseband stereo audio signals using a Drake stereo encoder. The AUDIO INPUT can also accept a 4.5 MHz audio modulated carrier by changing internal jumpers.

VMR806AG Desktop Agile Video Modulator Specifications

RF
Frequency Range:	7 to 806 MHz; Standard CATV channels 2 to 125, Broadcast TV channels 2 to 69. CATV T Channels, T7 - T14
FCC Frequency Offsets:	Automatic (+12.5 kHz, +25 kHz, or none as required for each channel).
Output level:	+45 dBmV (typical with 10 dB adjustment range).
Output Impedance:	75 Ohms, 10 dB return loss.
A/V Ratio:	Audio carrier level, adjustable from -19 to -12 dB (±2 dB) referenced to video carrier level.
Frequency Stability:	±5 ppm.
Intercarrier Frequency:	4.5 MHz ±5 ppm.
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.
In-channel C/N:	60 dB typical, 4 MHz bandwidth.
Broadband Noise:	-75 dBc typical, 4 MHz bandwidth @ +45 dBmV output.
VIDEO
Input Level for 87.5% Modulation:	0.6 Vp-p to 1.5 Vp-p. Manual gain adjust with front panel control. Overmodulation indicator provided.
Input Impedance:	75 Ohms, return loss of 20 dB minimum.
Frequency Response:	20 Hz to 4.2 MHz, ±1 dB.
C/L Delay:	Within 50 nSec. of 0 nSec. (standard), or FCC predistortion, (option).
Differential Gain:	3% maximum (10 to 90% APL).
Differential Phase:	3º maximum (10 to 90% APL).
AUDIO
Input Level for 25 kHz Peak Deviation:	100 mVrms to 2.5 Vrms. Manual gain adjust with front panel control. Overmodulation indicator provided.
Input Impedance:	10 K Ohms, unbalanced.
Pre-emphasis:	75 mSec., defeatable by internal jumper for BTSC baseband stereo encoder compatibility.
Frequency Response:	40 Hz to 15 kHz, ±1.0 dB referenced to 75 mSec. pre-emphasis curve. 40 Hz to 100 kHz, ±0.5 dB if pre-emphasis is defeated.
S/N ratio:	55 dB.
Total Harmonic Distortion:	1% maximum.
4.5MHz INPUT
(AUDIO INPUT Connector -	selected by internal jumpers).
Input Impedance:	75 Ohms.
Input Level:	+40 dBmV ±2 dB for -15 dB A/V ratio.
GENERAL
DC Power Input:	+10 to +18 VDC / 400 mA - from supplied AC adapter.
Supplied AC Adapter:	Input, 120 VAC / 60 Hz, wall adapter. Output, 12 VDC, 500 mA, maximum.
Operating Temperature:	0º C to +50º C ambient.
Size:	19" (48.3 cm) W x 1.75" (4.5 cm) H x 7" (17.8 cm) D.
Weight:	2 lbs. 12 oz. (1.25 Kg).

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