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Model 1931888-3011 Page/Party
®
to Radio Coupler
Pub. 42004-245A
f:\standard ioms - current release\instr. manuals (42004)\42004-245a.doc
01/98
Modification of Two Channel Radio Unit for use with Coupler
In order to be used with the Model 1931888-3011 coupler, the Two Channel Radio must be modified by
relocating jumper,
J2
from the factory setting.
J2
is located on the main motherboard WBA4448SYNxx
inside the radio unit. Perform the following steps to make the modification:
1.
Remove all cables from the radio.
2.
Remove the 4 screws securing the front cover.
3.
The 3-pin connector,
J2
is located to the left and adjacent to TB1. Use small needle-nose pliers to
move the shorting jumper from position 1-2 to 2-3.
4.
Reinstall the cover to the unit.
5.
Reconnect the cables.
Operation
The Model 1931888-3011 Coupler connects one radio frequency (channel) to one party line in the
Page/Party
®
or Call/Talk system, usually party line 5. When a remote radio is not in use, the coupler
monitors party line 5.
In order for a Page/Party
®
or Call/Talk user to contact a radio user, the caller must go off-hook on party
line 5. The resulting communication is simplex. This means that the radio user controls the flow of the
conversation with the push-to-talk, release-to-listen mechanism of the radio.
Call Originated by a Page/Party
®
or Call/Talk User to a Radio User:
Audio Path from Page/Party
®
to Radio:
The caller from a Page/Party
®
, Call/Talk or U/A station goes off-hook on the designated party line. This
causes the station’s output transformer to load the line (loop current on the line begins) at the Model
1931888-3011 coupler’s TB-7 and 8 and is detected by the Model WBA2757 Sensing PCBA inside the
coupler. The following relay functions occur:
1.
The sensing PCBA detects the off-hook condition on the party line and activates the
XFR
relay and
illuminates LED 3.
2.
The
XFR
(transfer) relay is activated by the sensing PCBA. It transfers the audio path from the
‘Radio-Page’ line to the ‘Radio-Party’ line.
3.
The
VOX
board detects audio from the system party line. When sufficient system party line audio is
present, it activates
VX1
relay and illuminates LED 1.
4.
VX1
(
VOX
) relay toggle operation is activated by the Voice Operated Switch (
VOX
) PCBA. While
the relay is activated:
•
It provides the audio connection path from the party line to the radio’s microphone-in circuit
(TB-12 and 13) via the coupler’s
RADIO VOL
control (
VC1
).
•
It disables
SQ1
(squelch) relay during party line talk mode for uninterrupted communication.
•
It provides a contact closure at TB-11 to ground to key the radio transmitter circuitry.
