E.F. Johnson Company Summit DM 975x, Руководство по обслуживанию

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OPERATION
3-30
Revised February 1997
Part No. 001-9750-005
Microphone audio, data, and the receiver are all
disabled by this function. Power is adjusted by rotating
the Select switch with the PTT switch pressed. The
display indicates the relative set point from 0-127 (127
is maximum power).
To exit this mode, the power setting of both PWR
SET 1 and PWR SET 2 must be checked by pressing
the PTT switch. The settings are saved in memory
when the mode is exited. The triangle/circle (encryp-
tion) symbol indicates if the current setting has been
checked. The maximum power output that can be set is
the rated power for the model of transceiver and the
type of channel (standard or talk-around). Refer to
Section 8 for more information.
3.11.4 POWER LEVEL 1 SET (TALK-AROUND
BAND)
The TA PWR SET function is used to set the
maximum power output for talk-around band. The
procedure is the same as for standard channels
described in Section 3.11.3 except that talk-around
channels on each end of the band are selected.
3.11.5 POWER LEVELS 2, 3, 4, 2W
The PWR LEVELS function is used to set power
levels 2, 3, 4, and 2W that can be selected for each
system when programming the transceiver. These
power levels apply to both standard and talk-around
channels. Power level 1 is set by the PWR SET and
TA PWR SET functions described in the preceding
and following sections. When this function is selected,
the data and microphone audio signals are disabled,
and only channel 381 (800 MHz) or 240 (900 MHz) is
selected.
To change the power levels, press the Select
switch when PWR LEVELS is displayed. PWR
LVL 2 - PWR LVL 4 and 2W PWR LVL are then
selected by turning the Select switch. To change the
power of the displayed parameter, turn the Select
switch with the PTT switch pressed. The relative
power output is indicated by 0-127 as described in
Section 3.11.3. The settings are saved in memory
when this mode is exited.
The power levels that can be set can be any power
in the minimum to maximum range for that transceiver
(see Section 8). The 2W setting can also be in this
range or 1-2 watts.
3.11.6 MODULATION BALANCE
The BAL ADJUST function is used to set modu-
lation balance over the entire standard and talk-around
frequency bands. This allows the microprocessor to
compensate for any changes that occur across the
band. This function generates a 67 Hz square wave
that is applied to the modulation circuitry. The micro-
phone audio signal and receiver are disabled.
To enable the balance adjust function, press the
Select switch when BAL ADJUST is displayed. BAL
ADJ 1 is then displayed which indicates the first
channel. The demodulated signal is viewed on the
CRT of a communications monitor and the Select
switch is rotated with the PTT switch pressed to
achieve the best square wave.
The balance for the other channels is set by
pressing the Select switch to select the next channel
and then repeating this adjustment. BAL ADJ 1 - BAL
ADJ 6 correspond to the six channels listed in Section
3.11.2. To exit this mode, all six channels must be
checked. The triangle/circle (encryption) symbol indi-
cates that the current channel has been checked. The
settings are saved in memory when the mode is exited.
3.11.7 TRANSMITTER HUM AND NOISE
This function is used to check transmitter hum
and noise. The six channels in Section 3.11.2 are
selected by the Select switch, and the transmit audio
signal and receiver are disabled.
3.11.8 DC VOLTAGE CHECK
This function displays the voltage of the 13.8V
power supply. Transmit channel 1 is selected, and both
microphone audio and transmit data are disabled.
3.11.9 DISPLAY TEST
This function tests all segments of the display in
sequence. If the PTT switch is pressed, all segments
are enabled but no power output is produced.