2
Contents:
Model Differences:
The VDA38H is for antenna or uni-directional cable systems and has the highest
headroom of any coax panel available in the market.
The VDA38B is for bi-directional cable systems providing a 5-42MHz back channel
for cable modems or interactive set-top boxes.
Accessories:
0dB
5dB
20dB
15dB
10dB
min
max
Inexpensive variable
attenuator
Inexpensive DC block
for RF
7
VDA38
Power Supply (15VDC @ 300mA)
Power/IR adaptor
CXIRWP
COAX/IR wall plate
breaks out the IR signal
from the coax cable.
Emitter jack for source
control. Power supply
included.
Powers the VDA38
remotely and has a built-
in IR wall plate.
(fits standard Decora)
MOD4000 4-Channel Digital Modulator
Things To Watch For:
Herringbone interference on modulator channel (diagonal lines):
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.
Herringbone interference on many channels, including modulator channels
(disappears when you remove the CATV/antenna feed):
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
will 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.
We recommend using only RG-6 coax when wiring a house for RF distribution.
Why? Although good RG-59 has only slightly more loss than RG-6, it is harder to
find a good RG-59 with wide bandwidth. RG-6 is a little more expensive and a little
harder to run (it is thicker). But you will avoid surprises if you stick to RG-6.
Models VDA38B & VDA38H Video Distribution Amplifiers
select
program
IR
pll frequency control
A
B
C D
4-Channel Digital Modulator
MOD4000
POWER
LED
EMITTER
TARGET
TO
TV
Mod input
+
1
5
vd
c
ir
o
u
t
g
n
d
A
B
(pwr)
TV output
VDA38B
CATV
3 X 8 Bi-Directional Video Distribution Amplifier
The VDA38B or VDA38H is the heart of any RF distribution system. Each is a 3
–
IN
by 8
–
OUT RF distribution amplifier that connects as many as 8 televisions to cable
or antenna while maintaining optimum signal strength to all TVs. Each also has the
capability of sending IR down each coax run for control of local TVs or video source
components.
Gain:
CATV/Antenna port to output
Modulator input to output
Output to CATV (reverse)
(5-42 MHz)
Isolation:
Modulator input to CATV/Ant
Max CATV/Antenna input:
Power Supply: (included)
General:
Width x height x depth (in)
Shipping weight
6.5” x 1.25” x 4.5”
4 lbs.
20 dBmV (+80 dBµV)
15 VDC @ 300 mA
>80 dB
5-1000 MHz
3 dB
-10 dB
n/a
20 dB mV (+80 dBµV)
15 VDC @ 300 mA
>35 dB
54-1000 MHz fwd
5-42 MHz reverse
3 dB
-10 dB
-15 dB
Specifications:
VDA38H
VDA38B
P
R
IN
T
E
R
'S
IN
S
T
R
U
C
T
IO
N
S
:
IN
S
T
R
,IN
S
T
L,
V
D
A
38
B
_H
,O
E
M
-
L
IN
E
A
R
P
/N
: 2
22
75
9
X
2
-
IN
K
: B
LA
C
K
-
M
AT
E
R
IA
L:
1
13
G
S
M
W
H
IT
E
P
A
P
E
R
C
O
AT
E
D
2
-S
ID
E
S
(
C
2S
)
-
S
IZ
E
: 8
.5
00
"
X
1
1.
00
0"
-
F
O
LD
IN
G
: A
LB
U
M
F
O
LD
, B
IN
D
IN
G
: S
A
D
D
LE
-S
T
IT
C
H
-
S
C
A
LE
: 1
-1
-
IM
A
G
E
2
O
F
4
