DRAKE VMM860AG Manuel - Page 4

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DRAKE VMM860AG Manuel
4
INSTALLATION
CONNECTIONS AND CONTROLS
All connections to and from each modulator are
made through the rear panel. Figure 4
illustrates an installation with (12) modulator
units combined through a passive signal
combiner. Additional channels can be added by
using additional fixed channel or agile type
modulators and either multi-port combiners or
combinations of two-port combiners.
INSTALLATION NOTES
Level adjustment provides optimum
performance in multi-channel installations.
The modulator outputs should be checked
periodically with a spectrum analyzer to
AUDIO INPUTS
AC POWER
CORD
VIDEO INPUTS
DC POWER
CABLE
RF COMBINER
POWER SUPPLY REQUIREMENT
This VMM860AG agile modulator requires more
current than the fixed channel units. Therefore,
new 12 position rack installations with multiple
VMM860AG modulators (up to 12) must use the
Drake PSM121 (or equivalent) high capacity
power supply module.
The power supply in the four position rack
system can power up to four VMM860AG
modulators or any mix of fixed and agile VMM
models up to four total modulators.
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.
RACK MOUNTING
Adequate ventilation is very important in
multi-channel installations. The RMM12 or
RMM4 cages should be spaced apart vertically
by at least one rack unit (1.75") height wherever
possible. Some air movement is mandatory in
enclosed rack cabinets. Excessive heat will
shorten component life and modulator perfor-
mance will be degraded without proper cooling.
MODULATOR UNITS
(Fixed channel and/or Agile types)
SYSTEM OUT
Figure 4
FREQUENCY CHART
The chart on the following page shows the
standard CATV channel coverage of the
VMM860AG. Where an offset is indicated, this
amount of positive frequency offset is added to
the frequency indicated in the middle column.
As shown, this occurs only on channels
required to be offset by the FCC.
HRC or IRC frequencies can be set by means
of an internal jumper. See Figure 3. No jumper
will result in the STD channel plan selection.
CATV CHANNEL OUTPUT FREQUENCIES
CATV
TABLE 1: CATV
CATV
BC
TV
+100
Visual Carrier
Frequency
Output Channel
Switch Setting
Frequency (MHz)
Offset (kHz)
02
55.25
NONE
03
61.25
NONE
67.25
NONE
04
05
77.25
NONE
83.25
NONE
06
07
175.25
NONE
08
181.25
NONE
09
187.25
NONE
10
193.25
NONE
199.25
NONE
11
12
205.25
NONE
211.25
NONE
13
14
121.25
±12.5
15
127.25
±12.5
16
133.25
±12.5
17
139.25
NONE
145.25
NONE
18
19
151.25
NONE
157.25
NONE
20
21
163.25
NONE
169.25
NONE
22
23
217.25
NONE
24
223.25
+12.5
229.25
+12.5
25
26
235.25
+12.5
241.25
+12.5
27
28
247.25
+12.5
29
253.25
+12.5
30
259.25
+12.5
31
265.25
+12.5
271.25
+12.5
32
33
277.25
+12.5
283.25
+12.5
34
35
289.25
+12.5
295.25
+12.5
36
37
301.25
+12.5
38
307.25
+12.5
39
313.25
+12.5
40
319.25
+12.5
325.25
+12.5
41
42
331.25
+25
337.25
+12.5
43
44
343.25
+12.5
45
349.25
+12.5
46
355.25
+12.5
47
361.25
+12.5
367.25
+12.5
48
49
373.25
+12.5
379.25
+12.5
50
51
385.25
+12.5
391.25
+12.5
52
53
397.25
+12.5
54
403.25
NONE
55
409.25
NONE
56
415.25
NONE
421.25
NONE
57
58
427.25
NONE
59
433.25
NONE
60
439.25
NONE
61
445.25
NONE
451.25
NONE
62
63
457.25
NONE
463.25
NONE
64
65
469.25
NONE
475.25
NONE
66
67
481.25
NONE
68
487.25
NONE
69
493.25
NONE
CATV
CATV
BC
TV
+100
Output Channel
Visual Carrier
Frequency
Switch Setting
Frequency (MHz)
Offset (kHz)
70
499.25
NONE
71
505.25
NONE
72
511.25
NONE
73
517.25
NONE
74
523.25
NONE
75
529.25
NONE
76
535.25
NONE
77
541.25
NONE
78
547.25
NONE
79
553.25
NONE
80
559.25
NONE
81
565.25
NONE
82
571.25
NONE
83
577.25
NONE
84
583.25
NONE
85
589.25
NONE
86
595.25
NONE
87
601.25
NONE
88
607.25
NONE
89
613.25
NONE
90
619.25
NONE
91
625.25
NONE
92
631.25
NONE
93
637.25
NONE
94
643.25
NONE
95
91.25
NONE
96
97.25
NONE
97
103.25
NONE
98
109.25
+25
99
115.25
+25
CATV
BC
CATV
CATV +100
+100
TV
100
649.25
NONE
101
655.25
NONE
102
661.25
NONE
103
667.25
NONE
104
673.25
NONE
105
679.25
NONE
106
685.25
NONE
107
691.25
NONE
108
697.25
NONE
109
703.25
NONE
110
709.25
NONE
111
715.25
NONE
112
721.25
NONE
113
727.25
NONE
114
733.25
NONE
115
739.25
NONE
116
745.25
NONE
117
751.25
NONE
118
757.25
NONE
119
763.25
NONE
120
769.25
NONE
121
775.25
NONE
122
781.25
NONE
123
787.25
NONE
124
793.25
NONE
125
799.25
NONE
126
805.25
NONE
127
811.25
NONE
128
817.25
NONE
129
823.25
NONE
130
829.25
NONE
131
835.25
NONE
132
841.25
NONE
133
847.25
NONE
134
853.25
NONE
135
859.25
NONE
5