®
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. Units should be
spaced apart by at least one panel height
wherever possible, and some air movement is
advisable in enclosed rack cabinets.
Excessive heat will shorten component life and
modulator performance will be degraded
without proper cooling.
CONNECTIONS AND CONTROLS
All connections to and from each modulator
are made through the rear panel. Figure 3
illustrates an installation with 12 modulator units
combined through a passive signal combiner.
Additional channels can be added by using
additional VMM 600 or VMM 860 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
maintain a ±1 dB variation of adjacent
channel carriers.
VMM 600's/VMM 860's
AUDIO INPUTS
VIDEO INPUTS
AC POWER
CORD
DC POWER
CABLE
INSTALLATION
R.L. DRAKE COMPANY
230 INDUSTRIAL DRIVE
FRANKLIN, OHIO 45005 U.S.A.
Figure 3
SYSTEM OUT
RF COMBINER
SPECIFICATIONS
Specifications subject to change without notice or obligation.
54-600 MHz.
Factory set to one of the following
channels:
Cable Channels 1-86, 95-99 or
UHF-TV Channels 14-35.
600-864 MHz.
Factory set to one of the following
channels:
Cable Channels 87-135 or
UHF-TV Channels 36-69.
+45 dBmV, minimum.
Adjustable over a 12 dB range.
75 Ohms, return loss of 12 dB.
Audio Carrier -10 to -22 dB
referenced to video carrier,
adjustable.
+ 5 kHz (Visual Carrier).
4.5 MHz, ±50 Hz.
All aeronautical channels are offset
positive.
-65 dBc, measured at -15 dB A/V
ratio and with modulator output
level of +45 dBmV.
-95 dBc, referenced to video
carrier.
(4 MHz BW and +36 MHz offset).
1 Vp-p +3 dB, manual gain adjust
with front panel control.
75 Ohms, return loss of 18 dB
minimum.
20 Hz to 4.2 MHz, +1 dB.
65 dB minimum, luminance
weighted.
VIDEO (continued)
Differential Gain:
Differential Phase:
C/L Delay:
AUDIO
Input Level for 25 kHz
Peak Deviation:
Input Impedance:
Pre-Emphasis:
Frequency Response:
4.5 MHz Intercarrier Stability:
Total Harmonic Distortion:
Hum and Noise:
GENERAL
DC Power Input:
Operating Temperature:
Size:
Weight:
+3% (10 to 90% APL).
+3 degrees (10 to 90% APL).
Within 50 nSec. of 0 nSec.
(standard), or
FCC predistortion, (option).
100 mV to 2.5 Vrms;
manual gain adjustment
with front panel control.
10 K Ohms, unbalanced.
75
µ
S. (Defeatable via
jumper setting for BTSC
baseband stereo
compatibility).
40 Hz to 15 kHz, +1.0 dB
referenced to 75
µ
S
pre-emphasis curve.
(40 Hz-100 kHz ±0.5 dB if
pre-emphasis is defeated).
+50 Hz, frequency
synthesized.
0.5% Maximum.
-65 dB minimum, referenced
to 25 kHz peak deviation.
+12 VDC @ 150 to 220 mA,
channel dependent.
+5 VDC @ 75 to 100 mA,
channel dependant.
0°C to +50°C.
1"W x 3.5" H x 7.5"D.
11 oz.
RF
Frequency Range:
VMM600-
VMM860-
Output Level:
Output Impedance:
A/V Ratio:
Frequency Stability:
Intercarrier Frequency:
FCC Frequency Offsets:
Spurious Outputs:
54 to 1000 MHz
Broadband Noise:
VIDEO
Input level for 87.5%
modulation:
Input Impedance:
Frequency Response:
Video S/N:
SPECIFICATIONS
R
Order From:
800-423-2594
www.multicominc.com
multicom@multicominc.com
