Midland 70-1341, Руководство по обслуживанию

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PREPARATION
70-1341/1344/1441/1444
SETUP
1. Remove the cover from the chassis, starting at
the back.
2. Connect a resistive 50

RF load and wattmeter
to Antenna Connector J501. Connect 13.6 V DC
power to Accessory Plug J202.
3. Connect a 3.2

, 20 W resistor to pins 4 and 6
of J202. The jumper between pins 5 and 6
must
be temporarily removed to make this
connection. The resistor serves as a constant
load to replace the speaker’s inconsistencies.
CAUTION:
Both speaker terminals are LIVE.
Never ground either one. Connect grounded
receive audio measuring equipment to only one
side of the speaker, and chassis ground.
Normally voltage measurement will be half of
true values.
4. Make sure the radio is turned off. Connect the
Programmer to Programming Port Jack J302.
Start the 70-1470 PC Programming software.
5. Turn the radio on. Set the VOLUME control to a
mid-position.
6. Upload the radio programming Data-Packet into
the PC and initiate Test Mode. Refer to the PC
Programming manual for details (70-998225).
SYNTHESIZER ALIGNMENT

VCO
1. Enter the following test frequencies (under the
Transmit Parameters window of the PC
Programming Test Mode screen):
A-Band
B-Band
RX Frequency (MHz): 136.00 150.00
TX Frequency (MHz): 136.00 150.00
2. Adjust Channel RX Tank L713 for 1.5 V at VC
(VCO Steering).
3. Activate transmit mode (using the programmer)
and adjust TX Tank L702 for 1.5 V DC at VC
(VCO Steering).

Reference Oscillator
4. Click on the “Transmit” button (any channel).
Measure transmitted RF carrier frequency
without modulation. Adjust trimmer cap X701 for
a carrier frequency within ±300 Hz of channel
frequency.
PA MODULE ALIGNMENT
The Titan VHF Mobile should be adjusted to have a
24 MHz channel spread at 50 W. To do so:
1. Change the TX test frequency to 148.00 MHz for
A-Band, or 162.00 MHz for B-Band.
2. Under the Test Parameters window, set the TX
Power Control to Normal. Click on the
“Transmit” button, and measure the RF power
level at Antenna connector J501.
3. Under the Adjust Data window, adjust the TX
High Power Level to obtain 50 W.
4. Set the TX Power Control to Low Power. Click
on the Transmit button, and adjust the TX Low
Power Level to obtain 25 W.
MODULATOR ALIGNMENT

Modulation Limiting
1. Connect a dummy microphone to Mic Jack
J302. Apply 3 V
rms
of 1000 Hz signal to pin 1 of
J302, then initiate transmit by keying the dummy
microphone. Measure total carrier deviation and
make sure modulation limiting is 5 kHz for Wide
Band radios, or 2.5 kHz for Narrow Band. If
needed, modulation limiting can be adjusted by
connecting the programming cable to J302 and
using the 70-1470 software.

Microphone Gain
2. Under the Adjust Data window, adjust the
Modulation Sensitivity setting to obtain 3 kHz
deviation at 300 mV @ 1 kHz AF.

CTCSS/DCS
3. Remove the 1 kHz audio signal from J302.
4. Using the programmer, add 250.3 Hz CTCSS
tone to the transmit test .
5. Adjust CTCSS deviation to ±750 Hz ±10 Hz for
wide band, or ±375 Hz ± 10 Hz for narrow band,
using the programmer.
6. Change the CTCSS tone to 67.0 Hz.
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