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Figure 2 - Inserting And Removing Portable Radio Unit
MOBILE CONFIGURATION
The following procedures permit the recharging of the port-
able radio unit battery pack and the functional conversion of
the portable radio unit into a mobile configuration.
1.
The power switch on the portable radio unit battery
pack may be in either the ON or OFF position.
2.
Insert portable radio unit into charging compartment
with its speaker facing outward (see Figure 2.).
3.
Slide the POSILATCH toward the portable radio unit
until you feel it engage and the red RADIO EN-
GAGED indicator lights.
4.
Turn the VOLUME switch on the vehicular charger
unit to the ON position. Then adjust the VOLUME
control for a comfortable listening level from the ex-
ternal speaker.
5.
The red CHARGE indicator will light and remain lit
until the portable radio unit is removed or until the
vehicular charger unit circuits sense that the battery
pack has reached its total charge capacity, at which
time the green READY indicator will also light, indi-
cating that the charger has switched to trickle charge
rate.
6.
The red XMIT indicator will light each time the PTT
switch on the external microphone is activated.
7.
To remove the portable radio unit from the charging
compartment, press the push-button release on the
POSILATCH and slide the latch away from the port-
able radio unit. The red RADIO ENGAGED indicator
will turn off and the portable radio unit can be re-
moved from the charging compartment (see Figure
2.).
CAUTION
DO NOT use the antenna to remove the port-
able radio from the charging compartment.
SPECIAL OPERATING PROCEDURES
FOR THE TPX™ 8403/8603 RADIOS
The Vehicular Charger unit will accept either the M-PA,
M-PD or TPX series Personal Radio Units. However, since
the TPX series operates to the requirements of the GE-
MARC V system, the following operational procedures must
be observed when a TPX radio is used in conjunction with
the Vehicular Charger Unit.
1.
When initiating a call, the push-to- talk switch
(PTT) must be keyed and then released to hear the
channel acquisition tone. The audio from the ve-
hicular charger external speaker is muted each time
the PTT is keyed.
2.
When the TPX 8603 (with DTMF option) radio is
used in the vehicular charger, it is recommended
that telephone interconnect or dispatch overdial
calls be made using the number stored in the TPX's
memory locations. Numbers may be directly dialed
into the unit but they will not be accompanied with
audible feedback tones.
CIRCUIT ANALYSIS
The Vehicular Charger is comprised of a Charger board,
LED board, Display Full board, and a UDC board.
CHARGER BOARD
The Charger board contains the charging circuit with
voltage and temperature cut-off circuits, an 8 volt regulator
circuit, and a 12 watt audio amplifier.
Charging Circuit
When power is first applied to the charger, the voltage at
pin 5 of Comparator A7 is higher than at pin 6 due to the
charging time of C18. The higher voltage causes the output
at pin 7 of A7 to go high, keeping A13 turned off. This al-
lows the battery to start charging. A block diagram of the
Vehicular Charger is shown in Figure 4.
Charging current flows through series connected resis-
tors R21 and R22 to regulator transistor Q3. The output of
Q3 is connected to the positive charging contact of the bat-
tery. Test Point TP2 provides a convenient place to monitor
the positive battery contact. A portion of the charging cur-
rent is routed through resistor R24 and transistor Q2 to turn
on CHARGE LED DS3 on the LED board and to provide a
trickle charge when Q2 turns off. The series connected
L B I-31864
charge circuit determines the high charge rate and is control-
led by the temperature cut off circuit.
Charger Control Circuit
The Charger Control circuit consists of a temperature cut
off circuit and battery charged memory circuit. The tempera-
ture cut off circuit consists of integrated circuit A13, a
bridge circuit comprised of R29, R30, R33, thermistors RT1
and RT (BATT), and associated circuitry. Temperature cut
off IC A13 monitors the temperature of the charging insert
through thermistor RT1 and the temperature of the battery
pack through internal thermistor RT (BATT). It also controls
transistors Q3 and Q4, turns the " READY" indicator on
when the battery pack is fully charged, and provides mem-
ory to prevent the same battery pack from being recharged at
the high rate.
Thermistors RT1 and RT (BATT) are connected with
R29, R30, and R33 to form a bridge circuit (see Figure 3).
The output of the bridge circuit is connected to terminals 13
and 14 of A13.
Figure 3 - Simplified Temperature Cut Off Circuit
When the battery pack temperature is more than 10°C
(18°F.) below ambient, thermistor RT (BATT) exhibits a
high resistance, causing the voltage on A13-13 to be larger
than the voltage on A13-14. (The same thing would occur if
there were no battery pack present). There is no output from
A13-6 or A13-10. Transistor Q3 and LED READY indicator
DS2 remain off. The battery pack charges at the trickle
charge rate, determined by series resistance R24, until the
temperature is less than 10°C below ambient. At less than
10°C below ambient, the voltage at A13-13 is still larger
than the voltage on A13-14, the output at A13-6 goes high
causing transistor Q4 to conduct, turning Q3 on and begin-
ning the high rate charge.
3
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