FM TRANSMITTER
TR
EM
1000
HE
DIG
PLUS
COMPACT
Technical Manual 1v2 November 2019
22
1) Connect the multiplex signal to the
MPX
connector. The multiplex signal is already pre-
emphasized; as such, using the MPX input, the filtering and stereo encoding stages are
skipped and the signal will not be further preemphasized.
2) Using the
SETUP
menu, set the modulation mode to
Mpx
.
Selecting the preemphasis according to the local standard is not required, as it is irrelevant in
this mode. However, it is recommended that this be done anyway.
If the length of the cable delivering the signal to the MPX connector is only a few meters long,
a 50 Ohm (RG58) cable can be used. If the distance is greater, a 75 Ohm (RG59) or 92 Ohm
(RG62) cable should be used.
2.1.4 Connection to LEFT, RIGHT, or MPX modulation connectors
The EM 1000 HE DIG PLUS COMPACT supports both balanced and unbalanced audio signals
according to the connection that is made in the three
LEFT
and
RIGHT
XLR connector contacts.
The input impedance for these contacts is pre-set at the factory at 10KOhm resistivity (5KOhm
for unbalanced connections), which can be decreased to 600 Ohm if necessary, as explained
further ahead.
Normally, an XLR audio input with balanced connection is used for connection to the balanced
output of a professional mixer.
Alternatively, an unbalanced connection can be used, and is useful for output connections on
inexpensive devices, without a perceptible degradation in the audio signal.
Alternatively to connection to the
LEFT
e
RIGHT
connectors, an externally created multiplex
signal can be connected to the
MPX
connector. In this case, connection should not be made
to the
LEFT
and
RIGHT
connectors.
The MPX connector is internally connected in parallel to the RIGHT connector. As such, if
the MPX connector is in use, the simultaneous connection of signals to the LEFT and RIGHT
connectors is not possible. In such case, the highest impedance position is 5KOhm.
- Balanced connection to the LEFT and RIGHT connectors
The output for a mixer or any other audio processor that drives a transmitter with a balanced
coaxial cable should be connected at pin 3 (-) and pin 2 (+). The cable shield, connected to the
ground of the audio driver device, must be connected to pin 1.
Balanced connection offers the greatest advantages. For example, cables connected to a
source can greatly exceed 100 meters in length.
- Unbalanced connection to the LEFT and RIGHT connectors
For driving with an unbalanced signal, input pin 3 must be short-circuited with the ground and
the shield to pin 1, while the signal must go to pin 2. In such case, the highest impedance
selection will be 5KOhm rather than 10KOhm.