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Example of Dip Switch Settings
Switch Band/Channels
1 2 3 4
CVT 3UB/UHF
HS-2
Cable or
Antenna
Channel Vision
MULTI ROOM VIDEO TECHNOLOGY
CVT - 15PIA
Source A/V Inputs
HS-3
Antenna (14-78)
Antenna (14-39) &
Cable (91-135)
Hi - Z
75Ω
Video Level (bottom)
Back View Bottom View
CVT 3ub/uhf Basic Setup
Note: Be sure to remove power from outlet before changing DIP
switch settings.
Note: Switch positions are relative to back of modulator.
Note: Black indicates where the switch should be.
Video
Input
L-Audio
Input
R-Audio
Input
10 30
C B A
1KΩ
75Ω
differences in signal strength may cause interference.
That's all there is to it. The information on the following pages will help you
configure more sophisticated home "networks" but is not necessary for basic
setups.
System Design Considerations
Sophisticated home "networks" involving many TV sets are feasible with the
CVT Modulator, but care must be taken to design an optimum TV signal
distribution system.
TV sets are designed for signals around 10dBmV. Signals substantially below
0dBmV result in weak, fuzzy, snowy pictures. FCC states 0dBmV minimum at
TV and 15dBmV maximum
Signals above 10dBmV may overdrive older TV sets which don't have modern
automatic gain controls (which can handle signals to 40dBmV). An inline
attenuator (pad) can be used to reduce these signals, and to balance radically
different signal strengths at all your TV's.
Signal strength decreases with coax cable length, and through connectors,
splitters, and combiners, so it's important to determine how much cable and
what in-line devices you'll be using, and adjust your input signal levels with
amplifiers at the front end or in-line on your network to compensate for the line
losses. The charts on the back of these instructions will help you calculate
likely losses through coax cable runs and splitters.
In-line amps are powered through the coax cable and can be used to achieve
modest signal strength gains; more powerful, a/c powered amps offer more
amplification (and usually adjustable gain and tilt too). Your system should
provide 10dBmV to every TV (maximum is 15.5dBmV, per the FCC).
Reverse isolation is used to prevent the signal from your CVT from leaking out
to the antenna or cable input. Reverse isolation is accomplished by placing an
amplifier between your antenna or cable company input and the CVT
combiner. This prevents the CVT signal from propagating back up the input
line.
Another way to prevent leakage from your system is to cap all unused coax
cable ports on you network with appropriate terminators.
Bandpass filters stop unwanted frequencies while passing all others along.
They're handy if a channel you want to use for a CVT source is already in use.
Taps are used to redirect a portion of a signal from the "main" trunk line while
passing the remaining signal strength through. For example, a 12dBmV tap
would pass 29dBmV from a 30dBmV trunk line signal and pass the remaining
18dBmV to a branch line (minor signal loss of 1dB would occur in the trunk
line leaving 29dBmV)
Demodulators are used to demodulate the output of a cable box converter,
making it possible to assign the cable signal to any channel (cable boxes
usually limit your choices to channel three or channel four). Use a demodulator
to "condition" the cable signal before assigning it to a CVT input line.
120 VAC
Input
TV Band
DIP
Switches
RF
Output
Attenuator Impedance
DIP
Switches
Fuse
Cable (65-135)
Cable (59-86 )
Setting Up TV Channel Range
see note
below
** **
**Note: When using channel range settings 59-86 you must set
the dip switches, plug in the unit, set the front display to your
desired channel, unplug the power again and then your channels
will work.