The H881 modulator combiner hub
has inputs for 8 modulators
for distribution through a coax panel. Signals from
all 8 inputs are combined into a single
output.
This output can be
connected to the modulator
input of a coax panel such
as the H838HHR or
H838BID.
When used
with the H838, each of 8
locations has a broadband
feed as well as the ability
to insert channels into the
system.
ChannelPlus
Modulator Combiner Hub
1
2
3
1) Hook from the top
2) Swing into place
3) Push button to lock
OpenHouse modules attach from the top
tm
ChannelPlus model H616
Telephone Master Hub (4 lines x 6 phones)
Telephone Master Hub (4 lines x 6 phones)
Telephones
From
Telco
From
Telco
RJ31X
RJ31X
Out
Expansion
Ports
Expansion
Ports
R
T
R
T
4
R
T
R
T
3
R
T
R
T
2
R
T
R
T
1
Modulators
Channe
lPlusm
odelH8
81
VideoC
ombine
rHub(
8inputs
x1outp
ut)
+1
2
vd
c
G
nd
Outpu
t
Modula
torCom
biner8
x1
470M
Hzto8
60MH
z
Televisions
+12vdc
Gnd
IR
Modulators
CATV
/Ant
A
B
+Pwr
High Headroom Amp w/IR Engine
Adaptor
(included)
LED glows when
power is applied
Up to 8 TV locations
Input from up
to 8 locations
RG-6 Coaxial cable
RG-6 Coaxial cable
Model
H881
DVD, VCR, or Satellite
Modulator
Typical Installation
Antenna or cable
(H838HHR)
Cable only
(H838BID)
The H881 modulator combiner hub work like a zero-loss combiner. The
modulated signals you put on the inputs will appear on the outputs with
about 1dB of gain. When the output of the H881 is connected to one of
the modulator inputs of the H838, signals will automatically appear on the
outputs of the H838 at an FCC legal level.
Note: The H881 does not pass IR information. To control a modulator
from a remote location, use a modulator with IR control such as the H564
and connect to the B+pwr input of the H838.
Specifications: typical @ 25°C ± 5° C
Number of modulator inputs
8
Gain, modulator input to output
~1
Bandwidth
400-860MHz
Nominal modulator input level
25dBmV
Maximum number of modulated channels
16
Power supply (370-086 included)
dB
15 VDC @ 300mA
Model H838HHR shown
Connect modulators
to A or B inputs
Modulators
+15vdc
Gnd
Modulator Combiner Hub 8x1
400MHz to 860MHz
Out
350-086 power
supply (included)
Each of 8 locations can have
its own modulator for
distribution to the entire
system
Things To Watch For:
Herringbone interference on modulator channel (diagonal lines):
Herringbone interference on many channels, including
modulated channel (disappears when you remove the
CATV/antenna feed)
You may have chosen a channel number that is not completely
vacant. Distant UHF stations may not be watchable, but will cause
interference if you try to create a new channel at the same frequency.
Also, cable companies often have extra signals where there should
be none. Try moving the modulator channel to another number. You
may have to add a low pass filter to remove the cable company noise.
If the filter does not work, try adding a DC-block to remove common
mode interference.
: The RF amplifier can be overloaded by
abnormally strong signals. Often, you can cure the problem with a
simple attenuator. Use a variable attenuator and try to find a signal
level where the interference just disappears. Sometimes, the problem
is one station is far stronger than the rest. In this case, attenuating all
of the signals with a simple attenuator may cause the desired stations
to be weak (snowy). You must reduce the strength of the only
offending station. A common FM trap will help if the problem is a
nearby FM tower. If the problem is a nearby TV station, often the
station management can provide suitable filters.
No picture
Weak ChannelPlus UHF channel
Audio volume is low
No color on ChannelPlus channels
… Check that the TV and the modulator are tuned to the
same channel. For example, if the modulator is broadcasting on UHF
channel 16, make sure the TV is on UHF 16 rather than CATV 16.
UHF 16 and CATV 16 are at different frequencies.
… If the TV has a separate UHF
input, be sure that it is connected.
… The left and right audio inputs are combined
for monaural. For proper audio level, both right and left inputs must
be used. If you have a mono source, connect it to both right and left
inputs using an RCA ‘Y’ connector.
… You may have chosen the
incorrect cable standard. Not all televisions can accommodate the
1.25MHz frequency difference between the H and I cable standards.
See the section on programming.
