User Manual PS 155 / Issue 1
8
2001 ASL Intercom, Utrecht, Holland.
6.0 THE INTERCONNECTING CABLE
Special care must be taken in constructing
the interconnection cable.
Although ASL-intercom has taken great care
in shielding and filtering all RF components
from the unit, it is still very important that you
use the best quality cables and properly
construct any electrical and mechanical
construction.
•
Always use shielded cable(s) for the
interconnecting cable.
•
If possible, use a cable assembly of the
wireless intercom manufacturer.
•
Always use the supplied Sub-D9
connector, this connector is shielded.
•
Avoid long cables.
Both input and output are transformer
balanced audio lines.
The transformers are DC decoupled by
condensers. This is necessary for wireless
units that use the presence of a DC
resistance, at the input or output, to switch
from receive to transmit.
In case of asymmetric signals at the wireless
unit you may connect the negative signal of
the input or output to the ground (pin7).
The PTT switch contact
An external Push To Talk switch may be
connected to the interface. When the TX
mode switch (9) is in the PTT position the
interface reacts on this external switch.
When the pins 3 and 7 of the Sub-D9 are
shorted by the PTT switch the interface will
switch the wireless unit from receive to
transmit mode.
The total resistance of the used cable and
contact (in closed position) may not exceed a
DC resistance of 5000 ohms.
The TRANSMIT SWITCH contacts
These are located on pins 4, 5 and 6.
Most wireless units will need a contact to be
closed to change from receive to transmit.
The NO contact :
This is a contact that is Normally Open, it is
closed when the wireless unit needs to switch
to transmit mode.
In this case you need to use the pin 4, this is
the Common pin (C), and pin 5, this is the
Normally Open (NO) pin.
The NC contact :
This is a contact that is Normally Closed, it is
opened when the wireless unit needs to
switch to transmit mode.
In this case you need to use the pin 4, this is
the Common pin (C), and pin 6, this is the
Normally Closed (NC) pin.
In some cases a unit needs to see a special
DC resistance.
In these case the manufacturer can advise
you on what value of the resistor to use.
In most cases the resistor will be mounted in
the Common wire of the Transmit Switch
contacts.
Example of a cable to fit the Motorola GP300
Motorola connector
2,5mm jack
3,5mm jack
Tip 3,5mm jack (audio output)
Sleeve 3,5mm jack (gnd audio output)
Tip 2,5mm jack (audio input)
Sleeve 2,5mm jack (gnd audio input)
Pin 1 SubD-9 of the PS 155
Pin 2 SubD-9 of the PS 155
Pin 8 SubD-9 of the PS 155
Pin 9 SubD-9 of the PS 155
Pin 4 SubD-9 of the PS 155
Pin 5 SubD-9 of the PS 155
Pin 3 SubD-9 of the PS 155
Pin 7 SubD-9 of the PS 155
Resistor 4700 ohms
(9 strony)
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