VA-700
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Page 7 of 23
Revision 10
CONFIGURATION
The VA-700 may be configured for several modes of operation. This is achieved by various link settings as outlined
below.
The VA-700 is normally delivered set for internal clamp operation and no sub-modules fitted.
1.
No sub-module
LK 2 - LK 3 soldered on board.
LK 6 - LK 7 soldered on board.
2.
Sub-module:
See instructions for each module (Obsolete – no longer available. Reference for
previous modules sold already in existence).
Cable compensation:
Circuitry provides compensation for up to 300 metres of Beldin YR23769 cable, links 8a and 8b are used to provide
ranging of the compensation.
A short on link 8a will allow for cable lengths of 75 m - 300 m to be compensated.
Moving the link to position 8b will allow for cable lengths of 0 - 75 m to be compensated.
Clamping option:
Decide if the clamp feature of the VA-700 is required. In general the clamp feature is useful if the video signal is
always composite.
If you are using the VA-700 to distribute pulses or sub-carrier the clamp feature should be disabled (LK 1 installed),
otherwise LK 1 should be removed.
External clamp reference:
An external video signal can be used to provide the reference for the clamp pulse generator circuit in the VA-700.
The signal path from outputs 9 and/or 10 can be wired to the input of the clamp reference buffer amplifier.
On the VDA remove the link between LK 10 - LK 12,
and complete links LK 12 - LK 13, LK 14 - LK 15 and LK 16 - LK 17.
Remove R 70 and R 71 connect a wire link between the rear pads of the R 70 position, the R 71 position and
the rear pad of the unused R 80 position.
The external clamp reference can now be looped through from the connector 9 and 10 positions on the rear
assembly.
Alternately:
A terminated input for the external clamp reference can be provided by using only the output 10 connector
position.
On the VDA remove the link between LK 10 - LK 12,
and complete links LK 12 - LK 13, LK 14 - LK 15 and LK 16 - LK 17.
Remove R 71 and insert in the R 80 position.
Now wire the end pads of R 80 and the R 71 position together.
This will give a terminated input for the external clamp reference from output connector 10 on the rear
assembly.