LT0371 Issue 1.10
7 February 2018
Page 4 of 6
If the T-GEN and pre-amp(s) are not mounted close together then to increase immunity to any ambient
electrical noise, it is recommended that screened cable should be used and an ALIM9706 should be located
at the T-GEN input. This is shown in Figure 6.
Note that the segments of screened cable connecting the pre-amp modules to the T-GEN must have their
shields wired together and connected to the 0V input of J9 (Pin 2) or J1 at the T-GEN. Again the paging
microphone closest to the T-GEN will have priority if both PTT buttons are pressed at the same time.
Note that there are volume controls on both the ALIM and pre-amps(s), we recommend setting the ALIM
volume to maximum and adjusting each microphone separately at its pre-amp.
Figure 6 - Balanced Configuration, PA0688 to T-GEN 50, Non-emergency Microphone
Emergency Microphone For T-GEN
In the above arrangements, the remote microphone will not override tones, digitised speech, or PA
messages generated by the emergency microphone plugged into connector J1.
For
an emergency microphone located at the T-GEN
a suitable pre-wired handheld microphone with PTT
switch and plug is available (ME0290).
For
remotely located emergency microphone(s)
we suggest the arrangement shown in Figure 7.
Note that the segments of screened cable connecting the pre-amp modules to the T-GEN must have their
shields wired together and must be connected to the 0V input of J9 (Pin 2) or J1 at the T-GEN. Again, the
microphone closest to the T-GEN will have priority if both PTT buttons are pressed at the same time.
Note that there are volume controls on both the ALIM and pre-amps(s). We recommend setting the ALIM
volume to maximum and adjusting each microphone separately at its pre-amp.
PA0688 MICROPHONE PRE-AMP
SPEECH OUT+
SPEAKER IN +
SPEECH OUT
SPARE
-
+
MIC SPEECH IN +
SPEECH IN -
+24V
PTT-
0V
PA0688 MICROPHONE PRE-AMP
SPEECH OUT+
SPEECH OUT -
MIC
+24V
PTT-
0V
PA0846/646 ALIM
A+
A- A-
A+
INPUT
OUTPUT
+24V
0V
T-GEN
24V Power
SHIELD
OPTIONAL
(Repeat for further microphones)
+
+
-
-
0V
0V
SPEAKER IN +
SPARE +
47k
47k
MIC+
MIC-
PTT-
0V
LK1A, LK2A NOT FITTED, LK3A FITTED 2-3
J1
Figure 7 - Remote Emergency Microphone(s) for T-GEN 50