3 REAR PANEL CONNECTIONS
R1 R2 R3 R4 R5
R1 - RF OUTPUT Connector
This is the modulator output.
R2 and R3 - AUDIO INPUT Connectors
These "RCA" (phono) connector inputs accept
baseband audio from 250 mVrms to 3 Vrms
levels. NOTE: In the AG models, an internally
selected jumper can defeat the audio pre-
emphasis for use with a stereo encoder. See
Diagram on page 4.
For AG mono models, the inputs from the left
and right jacks are internally summed. Input
can be from a stereo source to both inputs or
from a mono source to just one of the inputs.
For the AS stereo models, R2 and R3 are the
left and right stereo channel inputs. A mono
source connected to an AS stereo unit should
be input to both connectors using a "Y" cable.
R4 - VIDEO INPUT Connector
This is the baseband video input to the IF
circuits. This input accepts baseband input
levels from 0.6 Vp-p to 1.5 Vp-p.
R5 - POWER / DC INPUT Connector
This connector accepts the appropriate mating
DC power cable from the supplied AC adapter.
Figure 2
MOUNTING
Adequate ventilation is very important in
multichannel installations. Units should be
spaced apart by at least one panel height
wherever possible, and some air movement is
mandatory in enclosed rack cabinets.
Excessive heat will shorten component life and
modulator performance will be degraded without
proper ventilation.
INSTALLATION NOTES
Level adjustment provides optimum
performance in multichannel installations.
The modulator outputs should be checked
periodically with a spectrum analyzer or signal
strength meter to maintain a ±1 dB variation of
adjacent channel carriers. Aural/Visual (A/V)
ratios should be held to -15 dB or less. The
output ‘RF’ and ‘A/V (Ratio)’ controls are used
respectively to make these adjustments.
4
SETTING THE INTERNAL JUMPERS
JUMPER FUNCTIONS
Refer to the INTERNAL JUMPER FUNCTIONS
diagram for a brief explanation of the two
jumpers used in the jumper settings.
Refer to the INTERNAL JUMPER SETTINGS
Diagram for proper jumper placement of the
desired mode.
ACCESSING THE JUMPERS
- First, make certain the unit is disconnected
from its power source.
- Next, remove the four #4 screws from each
side of the top cover. Save the screws for later
reassembly.
- Carefully remove the top cover by lifting it
upward from the chassis. The jumpers are now
accessible for setting as desired.
RF OUT
AUDIO IN
LEFT
RIGHT
VIDEO IN
POWER
INTERNAL JUMPER FUNCTIONS
Front of VMM860AG With Cover Removed
Shown in standard configuration
(no jumper). Add jumper for IRC or
HRC.
Audio Pre-emphasis jumper shown
in the ON position.
