8
KRAMER ELECTRONICS LTD.
6.
INSTALLATION
The amplifier is provided with four rubber feet packed in a separate bag. Fit the feet to the unit, place it on the
table remote from heat generating sources and make the required connections.
7.
CONNECTING TO VIDEO DEVICES
Video sources and output devices (such as amplifiers or recorders) may be connected to the amplifier through
the BNC connectors (VM-3V model) or 4p type connectors (VM-3S model) located at the back of the machine.
If looping is needed, the VM-3S
xl
and VM-3V
xl
should be used. For looping (allowing another amplifier or any
video acceptor to use the same video input) use a “T” connector on the video input, and branch the input, via
this “T” connector to the other acceptor. Release the TERMination switch of the VM-3V
xl
/VM-3S
xl
(Hi-Z
position) and terminate the line with 75 ohms load at the remote acceptor. Please keep in mind that the output
signal format will match that of the input signal format.
8.
USING VM VIDEO/AUDIO AMPLIFIERS
8.1
Turning on the Amplifier
NOTES
1. Amplifier should only be turned on, after all connections
are completed, and all source devices have been turned on.
Do not attempt to connect or disconnect any video signals to
the amplifier while it is turned on!
2. The socket-outlet should be near the equipment and should
be easily accessible. To fully disconnect equipment, remove
power cord from its socket.
1) Connect the amplifier's DC socket to an appropriate DC source. Observe proper polarity!
2) Operate the acceptors.
8.2 Coupling
The coupling function enables the operator to determine whether the incoming video signal is DC or AC
coupled. When DC coupling is selected and proper standard video signal is applied to the amplifier’s input, the
output signal is equal to the input signal. When AC coupling is selected, DC components of the incoming signal
are removed. DC coupling is always preferable since AC coupling might cause some linearity distortions in low
and high frequencies (due to imperfect behavior of capacitors). A problem may arise when the incoming signal
is riding on a DC offset especially when the acceptors are very effected by deviation of DC offsets (A/D
converters for example), which in turn results in a distorted picture. The coupling used in the amplifiers
described in this manual is AC.
8.3
Installing a VM Amplifier in a Video System
In fieldwork, it is sometimes necessary to add a monitor or a VCR. A small audio or video DA, and with the
capability to eliminate signal degradation, is the best solution. Figure 3 illustrates a typical field setup of a VM
amplifier (fed by a 12VDC source.)
For this setup, perform the following steps:
1) Connect your video or audio source to the input of the field operated DA (VM-3V/VM-3V
xl
, VM-3S/VM-
3S
xl
). Locate the DA as close as possible to your video source.
2) Connect a power source (battery belt, car battery) to the power socket of the DA. Verify that proper polarity
of power supply is maintained. Invert polarity if necessary. In extreme cases where external power is not
available, a 9VDC battery may be used as a power source for no more than 2-3 hours.
3) Connect your video or audio acceptors to the outputs of the DA.
