MultiDyne VAGC-100 - Manual (Page 4)

Instruction Manual, VAGC-100 INTRODUCTION 4
INTRODUCTION
The MULTIDYNE VAGC-100 is a high precision, automatic gain, equalization and chroma distribution
amplifier. The amplifier will restore proper video level from an input range of less than 0.4 Volts to more than 2
Volts. It will also compensate or equalize the input video due to cable losses from 1’ to over 4000’ with a precision
of less than 0.05dB. This is achieved while maintaining a linearity of better than 0.2 degrees differential phase,
0.2% differential gain at a signal to noise ratio higher than 72dB. The amplifier provides for the equalization of two
different cable types. It also has a fixed 1000’ pre-equalizer and a 2000’ to 3000’ maximum variable automatic
equalizer. The VAGC-100 stand-alone version operates from 100 to 240 VAC with an integral power transformer
and from a 12 Volt BP90 type battery using and extemley low noise internal DC to DC power converter. The noise
and distortion specifications do not change for AC or battery operation. In AC operation the common mode rejection
is 66dB. The units are idea for field and master control use, where fast breaking news or irratic level fluxuation do
not allow video monitoring and careful level settings. Additional applications include cable television head-ends,
fiber optic and satellite transport systems, ENG/SNG, helicopter feeds and sporting events where video signal levels
may irratically fluxuate. The VAGC-100 is a stand-alone unit with an internal AC and DC power supply. For more
permanent applications, up to 3 units can be converted to rack-mount.
OPERATION
The amplifier achieves its automatic gain and equalization control features by precisely measuring sync and
burst levels at the amplifier’s output after accurately clamping the input signal. A complex servo mechanism then
adjusts a modulator block for proper sync and burst amplitudes. If the video source started as standard signal before
the attenuation the original parameters would be restored after the attenuation. The system measures the
luminance peak white flag to set a gain limit of 100 IRE. If the sync level is low or clipped for some reason, the
amplifier will not over compensate with too much gain. The peak white flag will always be limited to 100 IRE.
INPUT CONNECTIONS
The VAGC-100 has a loop-through input with 2 BNC connectors labeled INPUT on the rear panel. The high
impedance, loop-through input allows several instruments to be looped together. The user can feed a video signal
to one of the BNC input connectors and then feed the second input BNC connector to another piece of equipment.
The end of the looping cable should be terminated into 75 Ohms.
OUTPUT CONNECTIONS
The six BNC video outputs are labeled 1 through 6 on the rear panel. The outputs are source terminated at
75 Ohms. Each output has precisely the same gain and phase characteristic. The video outputs are designed to
drive 75 Ohm video cables.
POWER REQUIREMENTS
The VAGC-100 operates from 110 and 220 VAC and 12VDC. The unit is factory set to operate from 110
VAC. An optional 110 or 220 VAC front panle power selector switch is available. An external wall mount power
supply is not required. The AC power cord is an integral part of the amplifier. The POWER LED will glow green
when the unit is powered up and operating properly. If the unit is plugged into an active outlet and the POWER LED
does not glow, check the internal fuse. If the fuse is blown, replace it with a 1/4 Amp fuse.
!!!!!!!!!! WARNING !!!!!!!!!!
DO NOT OPERATE THE UNIT AT 230 VAC. The power supply is factory set to operate at
115 Volts AC. See the section POWER SETTING on page 7.